Memory and Forgetting: A Comprehensive Analysis
Memory loss is a huge problem in an aging population.
No substantive cure for memory loss.
Forgetfulness does not always accompany aging.
Different types of memory loss:
Forgetfulness
Dementia
Alzheimer's
Confusion
The memory impairment that comes with aging may be due to confusion as well as memory loss.
Memory loss and forgetfulness may be preventable.
There are a number of different approaches to reducing forgetfulness
Background music
Categorization
Control
Daily behavioral changes
The goal of the paper began as a meta-analysis of efforts aimed to reduce forgetfulness
Too many promising approaches to aiding memory impairment to engage in a traditional meta-analysis
Look at the theoretical overlap of different known approaches that may enhance or impair memory
F. Not engaging in a meta-analysis of a single therapy because single therapies do not have therapeutic efficacy.
G. Examine the hypothetical overlap between various treatment modalities
II. Literature Review
A. Three types of memory as defined by Cowan, 2008.
1. Long-term memory
2. Short-term memory
3. Working memory
B. Repetition
1. Does repetition move information from short-term to long-term memory?
2. Does repetition lose its importance with brain changes?
C. Control
1. Inhibitory control in memory impairment
2. Inhibitory therapies can impair cognitive functions, including memory
3. Schilling et al.'s 2014 study of retrieval-induced forgetting
a. Someone is only .75 times as likely to remember an item after induced forgetting
b. Even people with poorer inhibition are subject to retrieval-induced forgetting
c. People can be taught to forget
D. Categorization
1. Connotations and denotations
2. Vlach and Kalish study of categorization (2014
a. Manipulated timing
b. Preference for massed over interleavened features disappeared with passage of time
3. Chunking
E. Emotion
1. Memory is not neutral
2. Salience is critical to memory
3. Walter and Meier, 2014
F. The Role of Sleep
1. Sleep seems to enhance memory
2. Lo et al. studied daytime napping and nocturnal sleep
a. Nocturnal sleep has a greater impact on memory consolidation for related word pairs
b. Both nocturnal sleep and napping benefit unrelated word pairs equally
G. Sleep and emotion
1. Emotion impacts the ability of sleep to improve memories
2. Cairney et al., 2014
a. A memory's emotional elements should be linked to its central constructs to optimize sleep-related enhancement
b. Sleep spindle cycles impact memory for negative emotional constructs
H. Hindering recall
1. Can people try to forget?
2. Spitzer, 2014
a. The relative baseline contributions of R. To F. appear to have a 2:1 ratio
b. RIF can impact recognition memory
I. Physiological changes
1. Many brain disorders are believed to be linked to physiological changes in the brain
2. Tu et al. looked at changes in the thalamus and its impact on memory
J. Other memory impairment
1. Not all memory impairment is forgetfulness
2. Confusion is a predominant form of memory impairment
3. False recognition study by Pidgeon and Morcom, 2014
K. Background music
1. Background music is believed to improve memory
2. Bottiroli et al. examined the impact of different types of background music on memory and other cognitive exercises
L. Ginkgo biloba
1. Examine use in patients with Alzheimer's and certain sub-types of dementia
2. Weinmann et al., 2010
III. Methodology-
In this comprehensive analysis, the author is going to explore the possible interactions between different existing interventions aimed at improving memory and reducing forgetfulness.
1. Additive
2. Multiplicative
3. Subtractive through interference
4. The author will compare the different possible interactions of multiple interventions, beginning with two different interventions and then adding additional interventions.
IV. Analysis
A. Table one- memory interventions
B. Table two- retrieval practice
C. Table three- retrieval induced forgetting
D. Table four- napping
E. Table five- nocturnal sleep
F. Table six- Mozart
G. Table seven- Mahler
H. Table eight- white noise
I. Table nine- no noise
J. Table ten- Ginkgo biloba
K. Table eleven- nocturnal sleep and Mozart
L. Table twelve- napping and Mozart
V. Discussion
A. Four interventions stand out as the most helpful
1. Repetition
2. Sleep
3. Classical music
4. Ginkgo
B. The combination of interventions may be the most helpful
C. The role of retrieval induced forgetting
1. Can retrieval induced forgetting serve as a proxy for forgetfulness?
2. Could interventions increase retrieval induced forgetting?
a. Table thirteen- Retrieval induced forgetting
VI. Recommendations
A. Get adequate sleep
B. Engage in repetition
C. Positive classical music in the background
D. Supplement with Ginkgo
VII. Conclusion
Memory and Forgetting: A Comprehensive Analysis
Department Name
for the degree of in the subject of City, State
Month, Year
Abstract
This paper is a comprehensive analysis of memory, forgetfulness, and current interventions aimed at improving memory. Rather than a meta-analysis examining a specific intervention, the study looks at multiple interventions and the possible range of impact that they could have if combined into a single therapeutic intervention. It finds that four interventions have tremendous potential for being used alongside other interventions: repetition, sleep, classical music, and Ginkgo biloba supplementation. These interventions are isolated because of their efficacy and also because they can be added to the existing treatment regimens of most people suffering from memory impairment without interfering with other forms of treatment. In addition, the treatments are affordable, do not require the intervention of a specialist, and can be handled in a wide variety of settings. The paper also looks at developments in memory care and suggests areas for further research.
Table of Contents
Introduction
Literature Review
Methodology
Analysis
Table one
Table two
Table three
Table four
Table five
Table six
Table seven
Table eight
Table nine
Table ten
Table eleven
Table twelve
Discussion
Table thirteen
Recommendations
Conclusion
Introduction
Memory loss is one of the most pressing problems linked to an aging population, with forgetfulness and the associated problems that it brings among the top concerns for the elderly and their caregivers, who must find ways to make lifestyle changes and adaptations that can keep people self-sufficient in the face of memory loss. Of course, the elderly are not the only members of the population vulnerable to memory loss. As people become more stressed, they suffer from cognitive problems, including memory impairment. The United States also has a serious problem with getting adequate rest, which is a barrier to memory. Furthermore, people with traumatic brain injuries, stroke, and other physiological changes to the brain may suffer from memory loss, forgetfulness, or confusion as a result of those injuries.
However, at this point in time, there has been no substantive cure for memory loss, nor have any treatments been found that can completely prevent memory loss. As a result, memory loss is frequently considered an expected part of the aging process, so much so that many people mistakenly believe it to be an inevitable part of the aging process and resign themselves to the memory loss process, assuming that short-term, long-term, and working memory impairments are inevitable. This acceptance of memory troubles as people age or as a side effect of other issues has led to a society that deals with memory loss and not really a society that challenges the memory loss paradigm.
While some people may joking refer to Alzheimer's as "old timer's" disease, in a nod at the memory loss and confusion that often co-occur with aging, it is critical to remember that forgetfulness does not always accompany age. Furthermore, the degree of forgetfulness that co-occurs with aging ranges wildly across people; some people experience no memory impairment or confusion as they age, which other people develop severe problems, including Alzheimer's and dementia, which are both associated with dramatic memory loss and confusion. Furthermore, the onset of memory loss can also vary dramatically from person-to-person, with some people noticing the onset of gradual memory loss in middle age while others do not notice any perceptible memory loss until old age. What these variables make clear is that memory is complex and memory loss, while clearly correlated with aging, is impacted by a number of different factors that are not necessarily age-related. Genetics, lifestyle choices, environmental factors, and brain usage over the lifetime all seem to be related to whether or not a person experiences memory loss and the extent of that memory loss. This is not to suggest that memory loss is completely forgettable; as with other health conditions that have genetic and lifestyle components, life style choices can only have a partial impact on disease onset. However, it is important to keep in mind that healthy behavioral choices can help preserve memory and forestall cognitive impairments.
Moreover, the memory impairment that comes with aging, which is often characterized by confusion and considered a precursor to dementia, may not actually be the result of pure forgetfulness as was once believed. People once assumed that old people lost short-term memory ability and long-term memories as they aged, which led to the confusion associated with memory impairment in the elderly. On the contrary, much of the confusion linked to old age may actually be due to memory confusion, so that novel experiences that are similar to prior experiences become confused with the prior experiences.
What this suggests is that ending the confusion associated with old age may actually be a separate challenge than ending forgetfulness and may actually require techniques that are not so much aimed at increasing memory but at decreasing memory confusion, which may, in fact, require directed forgetting. Understanding the relationship between confusion and apparent memory loss may, in fact, provide one of the keys to helping ameliorate some of the negative impacts of the more severe forms of dementia, which seem to be characterized at least as much by confusion as they are by generic memory loss.
While helping people deal with the symptoms of memory loss is the current therapeutic approach, it is important to keep in mind that both memory loss and forgetfulness may be preventable, at least to some degree. Furthermore, it may be possible to mitigate the impact of forgetfulness before it occurs by employing strategies that are known to improve short-term and working-memory function when faced with memory loss. In fact, doing so may be a better approach to improving memory than trying to treat memory loss after it occurs.
However, many of these approaches do not seem to be aimed at targeting true forgetfulness, but actually helping minimize confusion between different memories. Because confusion and forgetfulness have been treated similarly in the research, both will be examined as memory impairments, while acknowledging that they may have different biological or psychological causes, therefore a treatment that has a positive impact on forgetfulness may or may not have a similarly positive impact on confusion. None of the research suggests that therapies aimed at minimizing either forgetfulness or confusion would be contraindicated in a patient seeking treatment for memory impairment, regardless of the etiology.
As a matter of fact, while memory impairments are often discussed solely as memory loss, it is critical to realize that memory care professionals already target confusion and that there are a number of different approaches to reducing forgetfulness that appear useful in some scenarios. For example, background music appears to enhance memory, which means that playing background music may be useful in scenarios where a person wants to target memory increase. Categorization has an impact on memory as well, appearing to increase the ability to remember discrete bits of memory if they are categorized together. However, other practices seem to interfere with memory, including efforts to control memory. Taken as a whole, the research seems to suggest that daily behavioral changes can make a significant difference in normal memory loss, though the application of these changes in cases where there is a more severe memory loss is, at best, uncertain. Whether memory enhancement techniques that work in the normal population would have a significant impact on a patient diagnosed with dementia or Alzheimer's is a question that is not yet answered by the research.
Initially, the goal of this paper was to combine a meta-analysis of efforts aimed at reducing forgetfulness. However, as the author conducted the literature review, it became clear that there were simply too many promising approaches to aiding memory impairment to engage in a traditional meta-analysis and still be comprehensive in the approach to memory improvement. After all, many of the approaches were studied in isolation or without taking into consideration whether other additional factors that have been shown to improve memory were also being used. Furthermore, because the various different experiments measured memory and forgetfulness in a variety of different ways, attempts to quantify them for comparison would be rendered somewhat meaningless. Additionally, few of the experiments appeared to make an effort at defining and quantifying confusion or measuring whether any confusion was abated by the treatment, unless the therapeutic approach was specifically tailored towards limiting confusion, such as in directed forgetting exercises.
However, the biggest problem was the wealth of information and research out there that targets forgetfulness and promises to improve memory. There are a number of pharmacological interventions, both prescription and herbal that promise to improve memory; there are a wide variety of techniques that have been tested and proven to help improve memory; there is research into lifestyle choices including diet, exercise, and mental stimulation, that may prevent memory loss and confusion. Moreover, there is a huge amount of information about the different types of memory impairment. Alzheimer's disease is not memory loss; memory loss is a symptom of a larger disease pattern. Likewise, with dementia, the memory loss is a symptom. Treating the memory loss itself may not be meaningful in those scenarios because of the etiology of the disease. For example, it is known that Alzheimer's patients have a plaque build-up in their brains and many Alzheimer's medications have the goal of plaque removal, though whether the plaque causes the symptoms associated with Alzheimer's or is simply another symptom of the disease is not understood.
Because a meta-analysis of these various different approaches seems unlikely to yield usable data and, moreover, would ignore the potential impact of multiple treatments on memory disorders, other approaches needed to be considered. The paper could have focused on a meta-analysis of a single intervention and explore what the existing research had to say about the efficacy and reliability of that intervention. However, there are already many existing well-done comprehensive studies of individual approaches that either demonstrate results that are replicated in repeated studies or suggest that studies indicating positive results are not reliable because they cannot be replicated in other studies. Repeating that approach would not be contributing anything new to the field, but simply verifying what prior researchers have already discovered and analyzed.
Therefore, the author determined that a more innovative approach would be to examine the hypothetical overlap between various different treatment modalities. Though conducting the experiments combining the various treatments was beyond the scope of this dissertation, by examining the potential cumulative effects of these treatments, one can begin to determine whether or not various cumulative therapies should be examined and considered. While this will not provide conclusive evidence that multiple approaches should be used in tandem, it will provide direction to future researchers who are seeking guidance about which combinations of approaches are most likely to yield positive results.
Examining the potential overlap between various treatments or interventions is not merely an intellectual exercise. Although a comprehensive medical intervention was beyond the scope of this dissertation, it is not beyond the scope of many researchers practicing in the field of memory and reducing forgetfulness. On the contrary, major researchers are unveiling new discoveries in the field of memory seemingly on a daily basis. It would be wonderful for some of those researchers to take the information revealed in this comprehensive analysis and examine the interaction of multiple interventions on memory and forgetfulness to see if the real-life impact of using multiple modalities lives up to the potential for interaction revealed in the course of this analysis. The most promising interventions seem to be ones that could be implemented in a variety of different scenarios. For example, the relationship between classical music, particularly Mozart, and memory is somewhat dramatic, as is the relationship between nocturnal sleep and memory. Both of those interventions could be utilized in a variety of settings to help improve memory in the general population, as well as in the population of people suffering from memory impairment.
Literature Review
It is critical to begin with an understanding of what is meant by the terms memory, forgetfulness, and confusion, and the state of modern research into memory improvement. Doing so helps establish a baseline for what type of memory is considered normal and the degree of forgetfulness and confusion that is deemed acceptable in daily life. After all, very few people have perfect memories. Moreover, even those few notable people who appear to have perfect memories may be incorrect; it is impossible to verify that what they are remembering is actually exactly what occurred at that time period.
Furthermore, when looking only at recall, research into eyewitness testimony and identification reveals that even traumatic and unusual events, which would seem to be memorable, are not recalled with accuracy by most people. Expectations and filling in for missing information seem to impact recall in a significant manner, even in healthy, young populations without any identifiable memory problems. Therefore, some degree of confusion, forgetfulness, and misremembering is expected when discussing recall. Understanding the basics of memory provides a foundation for understanding what can be done to help improve forgetfulness. It can also help provide an understanding of whether memory improvement techniques that are helpful in a normal population can be applied to a population experiencing memory impairment.
The concept of memory will be explored when investigating the three types of memory, but the blanket definition of memory is that part of the brain that stores information for later use. Memory is further broken down into two main types: short-term memory and long-term memory. Short-term memory provides the storage for information to be used for almost immediate access. For example, a person who pulls up to a traffic light, which is red, may look away from the light and still know that it is red. Long-term memory provides the storage for information to be used in the long-term. The person who pulls up to a traffic light, which red, and knows that they need to check the traffic light to see when it turns green is accessing a long-term memory that a red traffic light will turn to green. Working memory seems to combine the two and provides the cognitive processing for the information; the short-term memory may remember that the light is red but the long-term memory is required to remember what a red light means. The two work together seamlessly in most people, so that once a red light is observed and processed, a person stops.
Forgetfulness refers to people no longer being able to access something that was once in their memory. Forgetfulness comes in different varieties. Many times, when people experience forgetfulness they lose their episodic memory, which means that they are unable to recall specific events from their own lives and information that they learned over the course of a lifetime. However, most people do not lose all of their memory. For example, many people who experience forgetfulness continue to retain their vocabularies, their ability to speak in a primary language and other languages that they spoke over a lifetime, and the ability to engage in basic cognitive functions, like simple math. Some people retain long-term memories, but experience forgetfulness in their daily lives, so that their short-term memories no longer seem to retain a usable amount of information. Other times people seem to have processing problems with moving short-term memories to long-term storage, so that new information does not have an opportunity to become memories.
Confusion is another type of memory impairment, but it is not the same thing as forgetfulness. With confusion, a person mixes up information. This confusion can occur in many formats. At a basic level, people may confuse similar words or concepts. At a more complex level, people may confuse what actually occurred in their lives with similar events or stories that did not actually occur. Confusion may also happen when people are unable to recognize their surroundings or the people around them, leaving them feeing disoriented. Confusion can be a serious problem because it is linked to people "wandering off" because their surroundings may be unfamiliar to them and they may be unable to find their way back home after leaving. As people age, confusion seems to be more common, and there is some belief that interference from similar experiences contributes to the experience of confusion, as similar memories, experiences, or ideas compete along the same associations and replace existing memories
Three Types of Memory
While people speak of memory as one thing, there are actually three different sub-types of memory and problems with one of those subtypes will not necessarily impact the other sub-types. The three broad types of memory are: long-term, short-term, and working memory. The three sub-types of memory work together to help recall and may not be completely separable, but do seem to play different roles and functions.
Long-term memory refers to memories that are available not only in a time period immediately after exposure, but at a later time when they are recalled. The time period between exposure and recall has to be sufficient enough for the person to have stopped thinking about the specific memory during that time period. "Long-term memory is a vast store of knowledge and a record of prior events, and it exists according to all theoretical views; it would be difficult to deny that each normal person has at his or her command a rich, although not flawless or complete, set of long-term memories" (Cowan, 2008). Long-term memory may include things like personal memories of childhood but can also be composed of facts and figures that are available for recall and have not been recently learned.
Short-term memory refers to the ability to remember information immediately after exposure and is related to earlier ideations about primary memory. Short-term memory is marked by a limited capacity, but it also is marked by immediate accessibility. Going into a room to pick up an item is a function of short-term memory, and forgetting why one walked into a room is an example of the type of forgetfulness impacting short-term memory. Furthermore, information can be in short-term memory but never make it to long-term memory, so that it was once accessible, but is no longer accessible. The forgetting of information that was held in short-term memory, as least to some degree, is expected and is not indicative of a memory problem. However, there are memory processing issues that can impact the ability to store and access information in short-term memory.
Additionally, the process whereby information is moved from short-term memory to long-term memory is not fully understood, but many memory malfunctions appear to be related to the transition process and either the failure to transfer information from short-term to long-term storage or the inability to access information that is in long-term storage. Furthermore, memory impairments seem to impact short-term and long-term memory in different ways, so that a patient can experience almost complete impairment of one process and not have the other aspect of memory impacted at all. "Long- and short-term memory could differ in two fundamental ways, with only short-term memory demonstrating (1) temporal decay and (2) chunk capacity limits. Both properties of short-term memory are still controversial but the current literature is rather encouraging regarding the existence of both decay and capacity limits" (Cowan, 2008). In other words, time degrades memories in the long-term so that the greater the passage of time, the less reliable the memory, though whether that is due to true forgetfulness or to confusion is not certain. Furthermore, in the short-term, memory is limited in that a person can only process and remember a finite amount of information, though that amount can vary widely with individuals.
Short-term memory is not only about recall and involves a third type of memory that may or may not be pure memory, since it appears to have a logical or cognitive component: working memory. "Working memory is not completely distinct from short-term memory. It is a term that was used by Miller et al. (1960) to refer to memory as it is used to plan and carry out behavior. One relies on working memory to retain the partial results while solving an arithmetic problem without paper, to combine the premises in a lengthy rhetorical argument, or to bake a cake without making the unfortunate mistake of adding the same ingredient twice" (Cowan, 2008). Therefore, like short-term memory, working memory is a type of temporary memory.
Describing working memory as temporary memory is only a partial explanation. Working memory, which seems to rely upon links and associations may have a significant influence on the confusion aspect of memory loss. This is because working memory may not just be temporary memory. It may also include a "heavy contribution of long-term memory, which reduces the working memory load by organizing and grouping information in working memory into a smaller number of units" (Cowan, 2008). Therefore, the chunking aspect often associated with short-term memory and considered part of working memory may be a reflection of long-term memory influencing short-term memory. "Working memory has been conceived and defined in three different, slightly discrepant ways: as short-term memory applied to cognitive tasks, as a multi-component system that holds and manipulates information in short-term memory, and as the use of attention to manage short-term memory" (Cowan, 2008). Therefore, working memory may not refer to memory in its familiar recall connotation, because it involves more than simply accessing information, but it is also necessary in order to access the information that has been stored. As a result, working memory is clearly a component in moving information from exposure to short-term memory, which is necessary, but not sufficient, for its movement into long-term memory.
Furthermore, the role of working memory may actually reflect innate intelligence in a way that has not yet been quantified, but that could help explain memory problems in later life. Many people think of memory loss as if there are holes in a person's memory, and that the memory of certain things has been destroyed. However, if this were the case, then memory loss would be absolute from the first time someone forgets. This is not the case; people frequently remember information that they once believed was forgotten. The remembering of previously forgotten information suggests that forgetfulness is not about information disappearing from memory storage, but more about having problems accessing that stored information. "Measures of working memory have been found to correlate with intellectual aptitudes (and especially fluid intelligence) better than measures of short-term memory and, in fact, possibly better than measures of any other particular psychological process…It has been thought that this reflects the use of measures that incorporate not only storage but also processing, the notion being that both storage and processing have to be engaged concurrently to assess working memory capacity in a way that is related to cognitive aptitude" (Cowan, 2008). In other words, memory is not simply about storage, but also about processing, because memory has to place information in context and has to be able to access information from the appropriate contexts. Therefore, it should come as no surprise that people who are better at processing are likely to experience greater memory recall.
At first blush, such an explanation may seem to offer little help to those who are experiencing memory loss and forgetfulness, because many people tend to think of cognitive ability as static. However, there is support for the idea that cognitive ability can change over a lifetime and that people can take steps to improve their own cognitive abilities. Furthermore, this idea has gained traction in the popular realm. There are video games, websites, apps, and more that claim to help people train their brains to improve cognitive ability. While these different approaches may not be proven, they are not without some scientific support. There is evidence that engaging in challenging cognitive activities, such as puzzles, games, writing, and reading, can delay or prevent the onset of Alzheimer's and other forms of dementia, by strengthening existing neural connections and even creating new neural connections, which reaffirms the idea that memory cannot be separated from cognition. Therefore, the suggested link between cognitive ability and working memory is one worth considering when examining any information on forgetfulness and memory loss.
Repetition
Many people think of memory as a largely involuntary process; a person either remembers something or does not remember it. Of course, there is acknowledgment that the initial element of memorizing material is voluntarily, but people may believe that is limited to semantic memory rather than episodic memory. However, research strongly suggests that there may be some highly voluntary components of memory, which, when utilized, can either dramatically increase or dramatically decrease the likelihood something will be remembered. From a young age, students are asked to engage in memorization exercises for school, such as with the memorization and recitation of a poem. However, directed memorization occurs even before that point, as parents repeat the same lessons for children over and over until those lessons are memorized. What these exercises demonstrate is that repetition is one of the cornerstones of memorization. There appears to be a link between the number of times a person is exposed to material and the material being available for later recall.
What is it about repeated exposure that makes it more likely that something will be moved from short-term to long-term memory? A very basic theory is that the more times something is repeated, the more opportunities for the brain to create a connection between that information and information that already exists within the memory. After that, each time the information is repeated, the early connection is reinforced, so that the connection gets stronger and stronger with repetition. Therefore, directed repetition at the time of exposure appears to increase the chances that new information will be remembered. This is true for the memorization of information, which is more likely when people are exposed repeatedly to the information, but is also true for information where repetitive exposure occurs naturally in the environment, allowing the person to make associations.
However, when one looks at memory loss in later life, especially memory loss associated with dementia or Alzheimer's, repetition appears to lose much of its importance in the role of memory. After all, people suffering from these diseases often lose their ability to recognize people that they have known for an entire lifetime. Furthermore, the repetition of information seems to have little, if any, impact on the ability of the patient to move new information from short-term to long-term memory. Therefore, repetition, alone, does not seem to provide any protection against item-specific disease-associated memory loss.
The fact that repetition may not have an impact on learning in patients with dementia is significant because it may point to the type of impairments that lead to dementia. However, it does not mean that repetition has no value or plays no role in the movement of information from short-term to long-term memory, but does suggest that repetition does not necessarily make it easier to access information that is stored in long-term memory. It also suggests that the physiological changes that occur in the brain with dementia or Alzheimer's alter the pathways that are formed by this repetition, so that associations that were once strong and vibrant can disappear over the course of either disease.
Control
One area of memory that is getting increased attention is the role of inhibitory control in memory impairment. A growing population of people are in some type of treatment or therapy aimed at inhibiting behaviors by preventing people from engaging in certain types of behaviors that are normally triggered by certain situations. There are benefits to those therapies, which aim to reduce unwanted behaviors and may make it easier for people to function in society. For example, people on the Autism spectrum often engage in behaviors known as stemming, which can include a wide variety of behaviors in response to stimuli, which may be considered socially inappropriate by observers. Behavioral therapy aims to eliminate or reduce those behaviors, so that the individual is more able to function in society without exhibiting behaviors that marks him or her as different from others and can cause socialization problems. The behavioral therapy is a form of an extinction exercise, with the goal to initially reduce the negative response, and then to eliminate the response. While this therapy is often employed to help people with special needs, it is certainly not limited to people with special needs. People with phobias and people with addictions may also benefit from behavioral extinction therapies, which aim to reduce the conditioned response to various stimuli and either replace it with neutral behaviors or replace it with positive behaviors. The potential applications for these various forms of therapy are almost endless, suggesting that they will increase in popularity as they become used across a wider spectrum of problems.
However, there is a very strong suggestion that these inhibitory therapies also impair some cognitive functions, including memory. While this memory impairment is not a goal of the therapies, it has been observed so consistently across therapies in different contexts that it is impossible to ignore its impact as a potential side effect, and leads one to wonder whether or not people can be taught to intentionally forget information. Intentional forgetting may not be entirely possible once information has been moved from short-term to long-term memory, however there is a growing amount of evidence suggesting that intentional non-remembering is not only possible but that it occurs frequently. Any time a person uses that aspect of memory known as working memory, there is likely to be some type of intentional forgetting. People are constantly bombarded with multiple stimuli in every scenario. It is impossible to pay attention to all of this information, process it, and remember it. Therefore, people direct attention to specific items, ranking some things as more important and some things as less important, which impacts what is remembered. At its very basic format, this is a form of memory control, although it may seem very unintentional to a person at the time that it is occurring. If people can unintentionally control what is processed into memory, then it clearly becomes possible to intentionally control memory.
In behavioral motor inhibition therapies, the attention is intentional; the subject is asked to direct attention to changing a motor behavior. Given that a person's attention is limited, this focus appears to create a focus on that behavior, thereby limiting the ability of the person's working memory to process surrounding information as efficiently and correctly as it would in other circumstances. The result is that people engaging in behavioral motor inhibition therapies experience memory problems related, not only to the time period during which they are undergoing therapy, but also related to any time period in which they are exercising the techniques that they use in their therapies.
Moreover, how those things are measured can result in very different interpretations of the correlation between motor inhibition and memory. There are so many different working definitions of both motor inhibition and memory that it can be difficult to substantiate a link between motor inhibition and memory without specifically administering a test aimed at studying memory in the context of immediate learning, but memory impairment can go far beyond not being able to memorize things as efficiently. Schilling et al. demonstrated that in tests of retrieval-induced forgetting, the use of item-specific cues is linked to greater retrieval-induced forgetting as a result of better response inhibition (2014). However, when the memory test is not based on item-specific cues, motor response inhibition is actually negatively correlated with retrieval-induced forgetting (Schilling et al. 2014).
The experiment by Schilling et al. involved 132 undergraduate students in a three-phase investigation into retrieval-induced forgetting. The subjects studied 64 category-exemplar pairs, received retrieval practice for half of the exemplars from half of the categories, and were then tested on all 64 of the category-exemplar pairs. Half of the participants were given a category-cued final test, and the other half was given a category-plus-stem-cued final test. The list of 64 pairs was arranged into blocks of eight items and randomly ordered with one pair from each category appearing in the block. Each pair appeared on a computer screen for three seconds. Subjects were asked to try to remember them by relating the pair to its category. In the retrieval practice, four subsets of 16 items, with four exemplars from four categories, were taken from the larger 64-item group. The subjects performed retrieval practice on this subset. Retrieval practice consisted of subjects receiving category-plus-two-letter-stem retrieval for the items in the to-be-practiced group. For the final test, participants were given 40 seconds to recall the studied exemplars. The benefit of retrieval practice was calculated by subtracting neutral items from practiced and cued items, while the impact of retrieval-induced forgetting was calculated by subtracting the performance of non-cued items from neutral items. In addition to the memory test, the researchers also administered the stop-signal task in order to examine response inhibition and instructed participants to withhold their responses if they heard a stop-signal tone, with the delay getting shorter if they complied with the stop-signal tone and longer if they did not, which provided the researchers with a rough estimate of the time it took them to stop an ongoing response (See generally Schilling et al., 2014).
The results were examined using a 2x2 Analysis of Variance (ANOVA). The results demonstrated that retrieval practice led to better recall of items, with a mean of 64.4% compared to 36.4% for non-retrieval practiced items (Schilling et al., 2014). Therefore, the basic practice effect on the retrieval of the items was significant, and could be simply examined by looking at how much more likely the retrieval practice items were to be remembered than the non-retrieval practiced items. A basic equation for examining that result would be: 36.4 x ____ = 64.4. The result is roughly 1.77. In other words, people exposed to retrieval practiced items were almost twice as likely to remember the stored information, suggesting that this retrieval practice plays a role in moving information from short to long-term memory, and may, thus fall into the working memory category.
However, Schilling also examined how retrieval could be used to induce forgetting in addition to remembering. While the impact of retrieval-induced forgetting was not as significant as the impact of retrieval-induced remembering, it was still considered statistically significant, particularly in the category-cued rather than stem-cued areas. The retrieval induced forgetting items were recalled 31.9% of the time compared to 42% of time for the neutral items (Schilling et al., 2014). A basic equation for examining that result would be: 42 x ____ = 31.9. The result is roughly .76, which means that someone is only .75 times as likely to remember an item after induced forgetting than a neutral item, which is close to 25% memory loss. Furthermore, induced forgetting had a relationship with the inhibitory stop reaction time, which was impacted by the type of cueing, suggesting that testing conditions would have an impact on retrieval-induced forgetting. Therefore, one might anticipate that other factors known to impact memory might, like test conditions, interact with retrieval-induced forgetting to change the likelihood of remembering that information after first exposure.
Another aspect that Schilling et al. examined was how recall is impacted by an items position in a test sequence. This is actually a component of retrieval-induced forgetting as the interference from other elements may hinder remembering. Their evidence supported the "view that when the potential for associative blocking at test is controlled, motor response inhibition ability predicts larger inhibitory aftereffects in retrial-induced forgetting, consistent with a common underlying inhibitory control process mediating the control actions and memories" (Schilling et al., 2014).
One of the interesting aspects of their research is that it combined the stop-it test with the rest of the experiment in order to examine the role that inhibition plays in memory and forgetfulness. They found that even people with poorer inhibition were subject to retrieval-induced forgetting on category-cued final tests (Schilling, 2014). This is significant for people with disorders where inhibition deficits are assumed, such as young children, people with schizophrenia, and people with Attention Deficit Hyperactivity Disorder (ADHD). These groups of people tend to exhibit retrieval-induced forgetting in category-cued tests, but not in item-specific tests. The researchers theorized that "by increasing the role of blocking on the final test, the use of category-cued recall complicates inferences that can be made about why a given effect of retrieval-induced forgetting is observed" (Schilling et al., 2014). In fact, it calls into question whether inhibition is the primary cause of retrieval-induced forgetting, and, if it is not, then retrieval-induced forgetting may not be based on competition or cues, as people have believed. Instead, it provides support for the response-override hypothesis of memory control, which suggests that "controlling memory retrieval is a special case of the broader need to override prepotent responses, a function thought to be achieved by the executive control processes of inhibition" (Schilling et al., 2014). Therefore, induced forgetting can be thought of as overriding contextually-inappropriate responses. As a result, it could have implications for treating the confusion that often accompanies memory loss and means that competition-based accounts are probably insufficient to explain some current accounts of retrieval-induced forgetting, which may reflect working memory capacity. In fact, they believe that it may support a counter-intuitive conclusion, which is that individuals who are more prone to retrieval-induced forgetting may actually enjoy other advantages, rather than disadvantages, in memory and cognition (Schilling et al., 2014). Therefore, one way to reduce retrieval-induced forgetting appears to be to have the subjects multi-task during retrieval practice.
Taken as a whole, what this evidence suggests is that people can be taught to forget, or at least not to pay attention to some details during the memory process. The idea that intentional forgetting could improve memory appears counterintuitive, but suggests that working memory plays a critical role in the process. When one revisits the idea of memory loss, it becomes clear that much of what is considered memory loss would more accurately be described as confusion. People may not have forgotten information, but may be unable to place the correct information within the correct context because of an abundance of information. If it is possible to direct people to forget certain information, it may be easier for them to access already-existing memories and place them within the correct context. Therefore, while retrieval-induced forgetting may not be sufficient, one its own, to actually improve memory and reduce forgetfulness, it may have potential applications in helping people learn to focus and control inhibition, which may have applications in reducing the confusion that is generally associated with memory loss.
Categorization
Another area of memory that relates to confusion as well as to recall is the notion of categorization. Most people understand that categories play a large role in memory. Beginning with a basic word association game, it becomes clear that each individual has connotations surrounding ideas, facts, and concepts, as well as the formal denotations of those various different tidbits of information. Moreover, these connotations are going to vary from person to person, which means that memory becomes very personalized for the individual who is seeking to try to remember information. These connotations, therefore, serve as proxies for categories and may or may not make sense to people other than the person doing the categorization. This is true even when people have had the same experiences because they may have attached different values and meanings to those experiences, which would place them in different categories for each individual person. However, the category, itself, is unimportant when looking at the topic of categorization in memory; what is important is that people tend to place information into categories, and, regardless of the category chosen, the fact remains that categorization appears to play a critical role in recall.
In fact, "memory has commonly been described as the process of encoding one item of information, storing that item of information, and then later retrieving that same item of information. Alternatively, categorization has commonly been described as the process of encoding multiple items of information, abstracting across items of information, storing an organized representation of that information, and then later retrieving knowledge in such a way that it can be generalized to new experiences" (Vlach & Kalish, 2014). This is true whether the memory is a fact-based item or whether it is a personal memory, which is sometimes referred to as an episodic memory.
To examine the interrelation of memory and categorization, Vlach and Kalish "manipulated the timing at which features were presented during category learning. For each category, one set of features was presented on a massed schedule and one set of features was presented on an interleaved schedule. Although the presentation timing of the feature sets varied (i.e., massed vs. interleaved schedule), all of the features were associated with the category an equal number of times during learning" (2014). Then, the study participants were tested in a forced-choice scenario, where they were presented with "one novel exemplar that contained massed features of the category, one novel exemplar that contained interleaved features of the category, and a distractor object that contained all novel features" (Vlach & Kalish 2014). The expectation was that if co-occurrence of frequency were the only elements contributing to abstraction, then were would be no differences in testing between the novel exemplar with massed features and the novel exemplar with interleaved features (Vlach & Kalish 2014).
What they found supports a conclusion that co-occurrence or frequency of features are not the only elements linked to abstraction. They discovered that "the timing at which category features were encoded and then later generalized had a significant impact on generalization performance" (Vlach & Kalish 2014). At the shortest 2-minute interval, they noticed a preference for massed features when compared to interleaved features, but by the 3-minute interval, this preference flipped (Vlach & Kalish 2014). Even more interesting is that by the 5-minute interval there was no clear preference and choices appeared to be random (Vlach & Kalish 2014).
To examine the interrelationship between memory and categorization, Vlach and Kalish looked at the timing at which features were presented in a traditional category learning exercise. "For each category, one set of features was presented on a massed schedule and one set of features was presented on an interleaved schedule" (Vlach & Kalish, 2014). Other than timing, the features associated with the presentation were the same. To test their memory of the items, the participants were then given a forced-choice generalization test. However, in this test, rather than just being exposed to the information learned during the study process, the subjects were also given one novel exemplar that contained massed features of the category, one novel exemplar containing interleaved features of the category, and a distractor object composed entirely of novel features (Vlach & Kalish, 2014).
Vlach and Kalish theorized that they would see no differences at test in choosing between the massed features and the interleaved features if the co-occurrence or frequency of exposure were the only variables impacting abstraction, but that the presentation timing and temporal dynamics of category learning would actually impact memory, resulting in differences at test between the two groups (2014). The specific hypothesis as that "learners use the retrievability of learned information to guide their abstraction of relevant information for generalization. Based upon the spacing effect literature and study-phase retrieval theory, we expected that features presented on a massed schedule would be more retrievable than features presented on an interleaved schedule immediately after learning" (Vlach & Kalish, 2014). As a result, the working hypothesis was that participants would choose the novel exemplar with massed features more frequently than the novel exemplar with interleaved features at the intermediate test but choose the features presented on an interleaved schedule more when tested after a delay (Vlach & Kalish, 2014).
For their study, Vlach and Kalish used 149 undergraduate students and broke them into four different test delay conditions: immediately after each learning block; immediately after all learning blocks; three-minute delay; and five-minute delay. Each subject was exposed to both massed and interleaved items. They used a laptop screen and speakers to present to a number of novel objects and linguistic labels to the subjects. The novel objects consisted of body features: head, body, ears, hands, and feet in different colors and shapes. Five of them were in-category and one was out of category. Each feature presented as relevant in the same number of times across the whole experiment. Each participant was exposed to ten learning blocks of 11 learning trials, five that were category presentation, and six that were filler trials. Each trial lasted 4s, so that an 11 trial learning block was 44 seconds. During each learning block, two of the prototypical relevant features were presented on a massed schedule and two on an interleaved schedule (Vlach & Kalish, 2014). So that timing would be the only feature that differed across the presentation, each learning block had three significant features: an equal co-occurrence of each prototypical relevant features; an equal number of intervening trials between each of the interleaved feature presentations; and an equal duration between the last exposure to a particular feature and the testing trials in which learners generalized those features to novel category exemplars (Vlach & Kalish, 2014). The goal was to examine the role that memory plays in categorization and generalization.
Vlach and Kalish were interested in examining the differences in massed an interleaved items across testing delay conditions and used a number they referred to as a difference score and compared it to the testing delay and found significant differences in the number of massed vs. interleaved test choices across the testing delays (2014). In the two immediate testing delay conditions, participants were more likely to generalize based upon massed features than interleaved features, but by three minutes, the participants were more likely to generalize upon interleaved features than massed features, and by five minutes they did not show a preference for either but seemed to be choosing randomly (Vlach & Kalish, 2014).
The differences in generalization across time suggest that learners are generalizing knowledge based on memory rather than simply based on categories, though categorization does play a role. While the study was helpful in showing the role that temporal presentation plays in memory and recall, the manner in which the results were presented make them impossible to incorporate into the current study. The results were compared to a theoretical zero result, but the zero result is not what one would have expected in randomized trials. Therefore the result while it could be compared to the other timed results in the same experiment, cannot be generalized to show either improvement or interference in a normal study. Unfortunately because it could not be generalized, its impact cannot be added to or subtracted from other results.
Despite this limitation, the results are enough to suggest that time interacts with the mode of presentation to impact short-term memory in a significant manner. Furthermore, "this work does suggest that discrimination and/or interference are not the only mechanisms underlying the temporal dynamics of learning in generalization… and that other processes may engender massing and spacing/interleaving effects in categorization tasks" (Vlach & Kalish, 2014). In addition, it may help illuminate the role of forgetting in memory, suggesting that memory can actually promote generalization.
For example, factually a person may look up information about how to remove a red-wine stain from carpet and discover that the reason people suggest club soda for wine stain removal is because the bubbles help lift the stain. If faced with a different type of stain, they may access that same information and try club soda on that stain, despite having no memory of learning about removing that type of stain. The memory provides a means of generalizing information to a broader category.
In a personal context, this can be beneficial, but it can also be very negative because of the chance of overgeneralization. For example, most racism and bigotry can be described as overly broad categorization of people in the groups experiencing prejudice. However, it can also be very beneficial to people, when a person employs categories rather than stereotypes. For example, a person who has previously been mugged while walking alone at night on an isolated street may look around to find himself in a similar scenario and change his behavior, even though he is not on the same street where he was mugged. The similarities in the scenarios place them in the same category and may help access memories related to that category. Obviously, there are some gaps in these definitions because they attempt to delineate cognitive process in a way that does not capture the interrelated nature of cognitive functioning, but they do serve as general guideline definitions.
While memory is not the same as categorization, it has long been recognized that memory can be enhanced by categorization. One of the best examples of this is the modern phone number. It is believed that people can keep seven plus or minus three items of information in their short-term or working memory. This means that, for most people, they can remember four to eleven different pieces of information upon initial exposure to them. However, if information is put into chunks or categories, a person can remember a greater amount of information than if the same information is placed in discrete packets. The concept of chunking allows people to remember more things in their short-term memories than they could if they were not associating the new material with information that is already stored in their long-term memory.
For example, a person can remember a greater number of letters if they are contained in words than if they are contained in single list of seemingly randomized letters. Likewise, numbers are frequently divided into units for easy memorization; the best example of that may be in phone numbers, which are composed of three chunks of numbers: a three-digit area code, a three-digit prefix, and a four-digit suffix. What this makes clear is that memory and categorization are interrelated, even if they are not exactly the same process. As with the issue of control, the relationship between memory and categorization appears to be one that implicates the use of the working memory and implies that memory cannot be wholly distinguished from other cognitive functions. In fact, one of the roles of memory may be to place information within the appropriate context. Additionally, it seems to suggest that working memory plays a mediating role between long-term and short-term memory that is highly dependent upon context and category.
To Vlach and Kalish, these results suggest that memory plays a greater role in cognitive processes than was previously recognized. "Taken together, these findings suggest that learners are abstracting and generalizing knowledge based upon what they remember, rather than generalizing solely on the basis of a category prototype or set of co-occurrence statistics across exemplars. As a result, understanding the nature of categorization and generalization likely requires understanding how memory and categorization processes interact over timescales" (Vlach & Kalish 2014). Therefore, at a minimum, an examination of memory also has to focus on categorization and time, giving at least three components to the memory process. However while memory cannot be attributed solely to categorization, that does not mean that categorization does not play a critical role in research. While time may attenuate the role of categorization on memory, the reality is that categorization does have a positive impact on memory at some point in time.
Categorization is borne out by other research. For example, people have an easier time remembering related words than they do remembering unrelated word-pairs. Association, which includes categorization, seems to trigger some type of memory response, so that memory of one member of a categorized group appears to enhance the likelihood of remembering other components of the category. Furthermore, when items are already familiar and placed into categories, they appear to be easier to recall.
Emotion
Another interesting component of memory is that it is not a neutral process. Emotions appear to play a role in memory, perhaps because they allow for the easier categorization of new information. In most contexts, highly emotional moments are more likely to be remembered, although the details of those events may or may not be remembered accurately. Furthermore, if an event is highly emotional and negative, it may not be remembered fully, correctly, or at all. For example, in Post-Traumatic Stress Disorder (PTSD), it is not uncommon for people to be unable to recall the specific details of a particular negative triggering event, despite the event being highly emotional.
In other instances, there may be a focus on certain details of the event to the exclusion of other details of the event. This can be detrimental, not only to the individual, but also to society. For example, while eye-witness testimony is given great weight by laypersons, professionals know that eye-witness testimony has notorious issues, not because of a lack of credibility among witnesses, but because people perceive that they will remember things more clearly than they actually do remember them. Moreover, this perception issue is multiplicative; people have a belief that others will strongly and accurately recall events that have occurred to them, which means people give more credibility to eyewitness accounts than they should based on objective evidence.
The idea of salience is critical to memory. Emotion is often linked to the idea of importance, in that those things people consider most important are more likely to have emotional contexts than things people dismiss as unimportant. Therefore, one would anticipate a memory enhancement for things that are considered important. "Prospective memory refers to the ability to plan, retain and retrieve an intention as planned. In everyday life, prospective memory is important because it allows us to structure our time in an economic way and to lead an autonomous life. It can also affect our reputation and self-esteem, for example, one may be perceived as conscientious and well organized or as unreliable and unstructured. Typically, we have more than one active intention and often, one intention is more important than another one" (Walter & Meier 2014).
However, even though salience has an impact on memory, salience is not sufficient to ensure that information is processed and stored in long-term memory. After all, people still forget information that is considered important, suggesting that importance interacts with other factors to determine how memorable something is for a person. Moreover, there are costs associated with assigning importance to one task and those costs are linked to how the information gets its importance. "Intrinsic and extrinsic motivation are directly related to importance manipulations and while extrinsic motivation induces strategic monitoring, intrinsic motivation enhances the activation of intention representation and leads to a performance advantage due to automatic retrieval" (Walter & Meier 2014). In other words, it is difficult to assign priority to other people's thoughts, which puts some limitation on memory improvement if that improvement is not tailored to the individual. While it can be difficult to assign importance to a task, externally, it is clear that an individual's own perception of importance can have a dramatic impact on the likelihood that the task will be remembered. Not only does importance increase the chance that something will be remembered, but it also impacts other cognitive processes. "It can affect ongoing task costs dependent on the type of motivation triggered (i.e., intrinsic or extrinsic)" (Walter & Meier 2014).
The Role of Sleep
While much of the memory process is still not understood, it is clear that sleep plays a role in the memory process. First, people who are well-rested tend to perform better on all cognitive tasks, suggesting a relationship between adequate sleep and optimum brain function. However, the relationship between sleep and memory is not a general one; there appears to be a very real relationship between sleep and memory, as if the sleeping brain plays a part in moving information from short-term memory to long-term memory, making it available for recall. In a study examining the impact of both nocturnal sleep and daytime napping on word-pair recall, sleep was found to have a beneficial effect on recall (Lo et al., 2014). "Nocturnal sleep was found to have greater facilitative effects on memory consolidation for related word pairs than daytime napping, but they benefited unrelated word pairs equally. These results suggest that both nocturnal sleep and daytime napping preferentially facilitates the offline processing of materials that are prone to forgetting" (Lo et al., 2014).
However, one might wonder why sleep impacts related and unrelated words differently. One would assume greater recall of related words in any circumstance because of a pre-existing association. Therefore, one would assume that the effect of both the sleep period and the pre-existing relationship would be cumulative, enhancing the impact of either factor beyond what it would have been in a stand-alone scenario. In reality, "the pre-existing semantic associations of related word pairs are resilient to forgetting over a short wake period; thus, physiological state after learning did not influence performance change" (Lo et al., 2014). As a result, a short nap did not have the enhancing impact one would expect, not necessarily because sleep was not helpful, but because, in those scenarios, sleep was not necessary to continue the semantic link of the associated words. "However, when wakefulness was extended, these pre-existing associations became vulnerable," so that the enhancement of a nighttime sleep interval was useful (Lo et al., 2014). In contrast, "the novel associations of semantically unrelated word pairs were fragile even over short intervals," which made even short-term sleep from daytime napping beneficial to the recall process (Lo et al., 2014).
In their experiment, Lo et al. examined the relationship between sleep and memory in populations with "normal" sleep patterns. A normal sleep pattern meant a habitual bedtime that was at night, a wake time in relatively early morning, between 5 to 9 hours of sleep, no strong preference for morning or evening, no persistent sleep difficulties, and no use of medications other than oral contraceptives (which are not believed to impact sleeping patterns) (Lo et al., 2014). They ran two different experiments. In experiment 1, half of the participants were assigned to a sleep group, half to a wake group. Members of each group were exposed to a paired-associate task with 80 cue-target word pairs displayed on a computer screen. 40 of the 80-word pairs were semantically related to one another, while 40 were not related to one another. In experiment 2, the experiment was within-subject and the subjects were given a napping opportunity and then retested after a napping game. In the wake condition, the participants played the puzzle game for an entire two hour period, and then experienced retesting. As with experiment 1, the subjects learned 80-word pairs divided evenly between semantically related and semantically unrelated word pairs, but they learned a new list for each of the five days that they engaged in the testing procedure. In both experiments, the participants were instructed to learn as many word pairs as possible and that their memory would be tested during a retest.
In experiment 1, they found that participants were better at learning related word pairs than unrelated word pairs and that the sleep and wake groups showed similar learning performance. Moreover, forgetting was greater for unrelated word pairs than for related word pairs, though the sleep group showed less forgetting than the wake group. Moreover, nocturnal sleep had a positive impact on the retention of materials, making it 27% more likely that the material would be remembered. Furthermore, a post-learning nap help alleviate the forgetting of unrelated word pairs, but did not impact the remembering of related word pairs (Lo et al., 2014).
Time also had an impact on remembering if the subject was awake. "For related word pairs, the change in the number of correct recalls was significantly less than 0, and thus, forgetting was statistically significant, across 12 hours but not 2 hours of wakefulness. More forgetting across longer wake periods (t62=3.92, P
Sleep and Emotion
Moreover, while sleep strengthens the memory process, this seems especially true for emotional memories, which tend to be "strengthened ahead of neutral memories during sleep-dependent consolidation" (Cairney et al. 2014). However, this enhancement does not apply to all emotional memories. The memory's emotional elements should be linked to its central constructs, not to its contextual features if this sleep-related enhancement is going to apply. In a study examining different types of sleep and their impact on both emotionally-linked and neutral images, Cairney et al. discovered that sleep spindles were linked to both an increase in forgetting and slower response times for neutral context, but were not negatively linked to memories with a negative emotional context (2014). Therefore, the researchers believed that sleep spindle cycles provide support for the memorization of emotionally salient memories, not just in strengthening those memories, but also by suppressing the memorization of neutral images (Cairney et al. 2014).
To examine the role that sleep spindle cycles had on the processing of emotional memories, Cairney et al. conducted a survey with 28 healthy participants without a history of sleep, psychiatric, or neurological disorders. These participants were assigned to two groups: wake and nap. The groups were evenly distributed for fender and age. They were also measured for sleepiness/alertness using the Stanford Sleepiness Scale and homeostatic sleep pressure (Cairney et al., 2014)
To expose the experimenters to a memory, the researchers used neutral foreground images and superimposed them on either emotionally negative or neutral background images. During the retrieval phase, the participants were presented with object images and asked to indicate whether it was a new image or an old one, and, if an old one, whether it had been associated with a negative or neutral image. The researchers had 80 negative and 80 neutral context images, which were balanced for content as well as emotional arousal and 320 neutral object images, which were put on a square yellow background and superimposed on top of the other images. In addition, the participants were asked to rate the emotional valence of the images and then to form a mental association between the context image and the object image, and then press the space bar when the association had been formed. After they were exposed to the images, the participants were assigned to a four hour retention interval of wakefulness or a four hour retention interval that included a two hour nap. Participants in the wake group could leave the study area, but were asked not to sleep, exercise, or engage in any form of active learning, while participants in a nap group were asked to sleep in a bedroom within a sleep laboratory for a nap of approximately two hours in duration, and then given time to wake. After the break interval, the participants were asked to complete a delayed test session, where they saw 40 new object images in addition to the 40 object images they had previously seen (Cairney et al., 2014).
To examine the relationship between sleep, emotional context, and memory, Cairney et al. "assessed the consolidation of context memory with an index of forgetting…and an index of RT change (delayed RT-immediate RT) for correctly recalled contexts using a 2x2 mixed ANOVA design" (Cairney et al., 2014). In addition, sleep recording were scored by sleep scorers, and then partitioned into different groups according to the amount of time spend in each sleep stage. These scores were further examined to highlight slow and fast sleep spindles, as well as measure central, frontal, and occipital channels (Cairney et al., 2014). They found that participants who napped during the retention intervals forgot fewer contexts and exhibited more RT speeding for correctly recalled contexts than those who remained awake. The awake group's average was 4.35, while the nap group's average was 5.51. A basic equation for determining the impact of napping on recalling context is 4.35 x ____ = 5.51. Therefore, napping appears to improve contextual recall by a factor of 1.27. Emotion did not appear to impact forgetting or RT change (Cairney et al., 2014).
What is even more fascinating is how sleep spindles appeared to interact with emotion to impact memory. Spindles counted at the right frontal EEG channel were predictive of the extent to which neutral contexts were forgotten over sleep, but not predictive of the extent to which negative contexts were forgotten over sleep (Cairney et al., 2014). Using an emotional context score (ECS) for all of the participants in the nap group, the researchers determined that a negative ECS showed that fewer neutral contexts were forgotten (Cairney et al., 2014). Moreover, some spindles were predictive of positive ECS, while some were predictive of slower RTs for correctly recalled neutral contexts across sleep spindles but not for negative contexts (Cairney et al., 2014).
Furthermore, the stage of sleep appeared to be important to memory. Time spent in stage 2 of sleep reduced forgetting of negative context and RT speeding for correctly recalled negative contexts (Cairney et al., 2014). However, there was not a relationship between other sleep stages and negative context forgetting or sleep stage and negative context RT. There was also no relationship between neutral contexts and sleep stage. However, the role of sleep stage in forgetting a negative context could provide important insight into the treatment of disorders where people replay negative memories repeatedly; there may be a therapeutic application of sleep therapy in those disorders. Furthermore, the researchers believed that their evidence provide support for the idea that the "selective benefits of sleep for emotional memory do not emerge when the "emotionality of a novel representation relates instead to its contextual features, thereby suggesting that emotional contexts are influenced by different properties of sleep to those that support central emotional memory information" (Cairney et al., 2014). They also found support for the idea that frontal cortex spindles might work to suppress neural contexts, but not negative contexts, which may support the idea that emotionally salient contextual information is consolidated during sleep (Cairney et al., 2014).
They also suggested that there is probably much more information to learn about sleep spindles and the roles that they play in memory. It is already well established that sleep spindles play a significant role in memory with people demonstrating increased sleep spindle activity after learning. In addition, the sleep spindle relationship with memory seems to be both forwards and backwards; in other words, people engage in spindles more after learning, but sleep spindles prior to exposure to new information is also associated with higher rates of retention. This occurs whether the spindles are naturally occurring during natural sleep or induced through pharmacological manipulation of spindle density (Cairney et al., 2014). The implications of that could be tremendous, because there could be a medication that could alter memory by changing the quality of an individual's sleep. Furthermore, while spindles are positively associated with memory, in general, they also seem to play a specific role in the memory process so that discriminatory memory processing is enhanced during sleep. The notion is that sleep spindles enhance selective memory retention. The more salient the memory, the greater the spindle activity. Furthermore, the relationship appears to work both ways, as pharmacologically manipulated sleep spindles could be predictive of greater retention rates of highly emotional or salient memories, particularly negative memories (Cairney et al., 2014).
Hindering Recall
One of the most interesting issues in memory is that practiced-recall may actually make forgetting more likely. "Retrieval-induced forgetting (RIF) refers to the finding that retrieval practice of a subset of previously studied items (RP+, for instance, Fruit Or____) may impair later memory for related unpracticed material (RP-, e.g., Apple)." (Spitzer, 2014). There are questions about why this happens, with some suggesting that the previously memorized items interfere with the later recall of other items rather than the explanation that RIF actually impairs the memory of later items (Spitzer, 2014). The root cause of this forgetting may be critical, since knowing the root cause could help alleviate situational forgetfulness that is analogous to RIF. However, an overview of studies into the issue provide inconsistent results, with some suggesting that context plays a role and that interference is to blame. Other studies suggest an overall dampening effect on memory and recollection (Spitzer, 2014). Moreover, how recollection impacts memory may be related to baseline memory strength, suggesting that memory enhancement activities and tools may need to be specifically tailored to the memory strength of the targeted audience.
Spitzer examined multiple different studies and found that there was tremendous variation in baseline accuracy levels, and that this baseline performance was a reliable predictor of the RIF effects (2014). He also espoused a possible signal detection view on RIF in recognition. According to Spitzer, recognition performance stems from the differential probability for true compared to false memory signals, when the subject is asked to determine whether they are being exposed to new or old material. Interference impacts the subjects' ability to accurately determine whether they have previously been exposed to certain stimuli or whether those stimuli are novel in the context of the experiment.
The clear difficulty with the experiments that Spitzer reviewed is that it seems very unlikely that any of the material was actually truly novel. It seems difficult, if not impossible, to truly control for recognition in testing about stimuli exposure because it seems improbable that a researcher would be able to select information that is truly novel for the subjects being examined. On the contrary, it seems very likely that the subjects would have previously been exposed to material, making it very likely that it is not novel and making it impossible to really determine if responses are actually true or false. The studies suggest that "RIF predominantly affects stronger memories, which, on intact NRP baseline, would substantially exceed the noise level of new items" (Spitzer, 2014).
Moreover, how people forget may be linked to their baseline. Spitzer asked, "if baseline levels explain the magnitude of RIF in recognition, may they also account for the qualitatively inconsistent RIF-patterns seen in previous 2P analyses of recollection (R) and familiarity (F) parameters" (Spitzer, 2014)? The relative baseline contributions of R. And F. To associative recognition appear to have a 2:1 ratio, so that RIF affects recollection about twice as much as it affects familiarity (Spitzer, 2014). What he concluded was that, "at least provisionally, the entirety of the surveyed data appears coherently accommodated by a simple signal detection framework, in terms of a proportional decrement of the affected items' memory strength. In this light, the past decade has brought accumulating evidence that RIF, unlike many other types of forgetting, can affect recognition memory, and the impairments therein might go beyond a mere mimicry of recall effects" (Spitzer, 2014).
Physiological Changes
Of course, while there are some external factors that impact memory and forgetting, the current theory is that most significant memory impairment, such as dementia and Alzheimer's disease are the result of structural changes in the brain and the impact that those structural changes have on memory. There is little evidence to suggest that these structural changes can be overcome through the use of memory enhancing techniques, though there is also little to suggest that memory enhancing techniques would somehow be contraindicated in this population.
To understand how brain changes can impact memory and forgetting, one can look at the role the thalamus plays in memory and how changes to the thalamus impact both memory and forgetfulness. The thalamus plays a critical role in the memory process, and damage to its subcomponents is linked to memory loss, not only the type of memory loss one sees with aging, but also dramatic types of memory loss, such as amnesia. In a study focusing on stroke patients with thalamic damage, Tu et al. sought to identify the specific damage these patients experienced and then compare the damaged areas to memory deficits (2014). Unlike most prior research into thalamic-damage linked memory loss, they did not examine short-term memory recall, but instead tested patients' long-term contextual detail memory. What they found was that, generally, the thalamic patients performed in the normal range on tests of cognitive function, including standard cognitive visual memory tests (Tu et al., 2014). This finding could have led them to question their initial assumption that thalamic damage would have a negative impact on memory and cognitive function.
Keeping in that short-term memory is only one aspect of memory, they did not draw the conclusion that normal range results on tests of cognitive function, including visual memory tests, meant that no memory impairment had occurred. Instead, longer recall seemed to pose problems, with a significant number of patients performing well below average in a delayed recall test and a verbal test (Tu et al., 2014). This led to a conclusion that "unilateral lesion focal to the left medio-dorsal nuclei of the thalamus, in the absence of damage to the mammillothalamic tract, impairs anterograde memory recall. The findings support the notion that the medio-dorsal nuclei play a role in long-term delayed retrieval of recall type memory processes" (Tu et al., 2014). Therefore, the role of physiological changes in the brain, specifically thalamic changes, must be considered when examining memory and forgetting. Likewise, researchers and other evaluators must be cautious when assuming that results that fall within the normal range for some tests indicate a lack of memory impairment, because memory can be impaired on multiple different levels without creating matching impairments at other levels.
Other Memory Impairment
While forgetfulness is the most commonly recognized memory impairment, it is important to recognize that there are other memory impairments, as well. For example, older adults may suffer from confusion that is linked to memory impairment. One such form of confusion is false recognition. False recognition refers to a person falsely believing that a novel event or experience has previously occurred. In the elderly, false recognition is a relatively frequent occurrence and is more likely to occur if a novel event is similar to something that was previously encountered. The result can be uncertainty about whether an even previously occurred. Research suggests that, as people age, they may suffer impairments, not only in the ability to remember things, but also in the ability to discriminate in memory. This results in an overlap of memory representations that promotes confusion and can make people uncertain whether events occurred, lead them to confuse multiple events, or mix the details of events together (Pidgeon & Morcom, 2014).
Pidgeon and Morcom compared two groups of people, one consisting of older adults (OAs) and one consisting of younger adults (YAs), to look at memory differences in the young and old. Both groups completed a significant battery of tests to determine baseline cognitive ability. Using stimuli that consisted of colored line drawings of categorized abstract and concrete items, the researchers exposed subjects to concrete items in 12 large categories and 12 single-item categories and abstract items in 12 large categories and 12 single-item categories. Half of the items in each of the stimulus conditions were abstract, half were concrete, and they were intermixed in a pseudorandom order. In experiment 1, the participants had a study phase, a 10 minute filled interval, and then a surprise recognition test. During the study phase, participants were not only exposed to the images, but also asked to rate them in terms of pleasantness. The 10 minute interval was filled with cognitive tests. Experiment 2 had the same procedures, but the test phase task instructions and response options were different in that participants were told that during the recognition test the items would either be identical to study items, similar to studied items, or novel, and then were asked to respond whether the items were old, similar, or new in addition to rating them. The researchers were seeking to determine the rates for false recognition in the group composed of older adults (Pidgeon & Morcom, 2014).
The baseline for both groups was similar, both in terms of the cognitive testing and in the groups' self-reports of their perceptions of the similarity of the different items. First, they determined that while people were likely to falsely recognize abstract items than concrete items, this was not age dependent, and did not depend on the degree of confidence the raters had in having been previously exposed to the items (Pidgeon & Morcom, 2014). However, there was greater false recognition in older adults for concrete items and large category items, but no difference in abstract items, with a t=5.29 for OAs compared to YAs for concrete items compared to a t=1.12 for abstract items in the same comparison, which was not statistically significant (Pidgeon & Morcom, 2014).
In addition, perceptual similarity did not appear to have the same impact on the likelihood of false recognition in the older adult and the younger adult groups. The OAs were significantly more likely than the YAs to falsely recognize concrete lures at all levels of perceptual similarity, with a t=4.24. However, for abstract items, conceptual similarity did not impact false recognition, but did for concrete items, with OAs being more likely to falsely recognize concrete items with high scores in similarity. What is interesting is that when respondents were given the option of selecting similar and not just old and new, the effect of age and the interactive effect of age and stimulus type appeared to disappear, particularly among highly confident responses. Moreover, "there was a clear age difference for concrete items (t (50) = 4.25, p < 0.001,d = 1.18), with OAs 12.2% more likely to falsely recognize concrete lures, and a smaller but significant age difference for abstract items (4.5%; t (50) = 2.02, p = 0.049, d = 0.56)" (Pidgeon & Morcom, 2014).
One of the goals of Pidgeon and Morcom's study was to try to help determine the cause of age-related increases in false recognition. One challenge that they encountered was that their study found a significant increase in abstract lure false recognition in OAs relative to YAs, which differed from prior research. They believed that this supported a theory of age-related reduction in mnemonic discrimination. Furthermore, the findings of larger effects of false recognition on concrete lures relative to abstract lures may be due to semantic overlap. OAs may rely more on gist. This may not have overall negative implications for memory in older people, because multiple overlapping representations in memory actually result in an increased likelihood of pattern completion (Pidgeon & Morcom, 2014). Therefore, the same things that contribute to confusion in older people can also help prevent actual memory loss, because overlapping memories create more neural connections that allow for pattern completion when details are missing from the actual memory.
Background Music
Studying factors that contribute to forgetfulness is important because it can help point to therapies that can be employed to improve memory. One of the easiest ways to improve memory may be through environmental manipulation because that can be done without the subject's intentional participation and could be implemented in a wide variety of setting, such as in a classroom setting or in an assisted living scenario. Background music, a non-invasive therapy that could be applied in conjunction with other therapies, has long been thought to improve memory processes, a theory that Bottiroli et al. tested.
Bottiroli et al. engaged in a study to examine the role that background music could play in aiding cognitive functions, including recall. They did not focus solely on memory, but on vocabulary, episodic memory, semantic memory, and processing speed. In addition, they examined affect through the use of a 20 question depression screening, which asked participants to rate on a 0 to 3 scale, the frequency with which they have experienced depressive symptoms in the last week. The vocabulary test involved identifying synonyms for 50 target words in an 8-minute time span. The episodic memory test began with a list of 15 concrete words and a study period of 2 minutes, and then asked to write down as many words as they could remember from the list in 2 minutes. To test semantic memory, participants were asked to write down as many words as possible, excluding proper nouns, beginning with three different letters of the alphabet, with 90 seconds for each letter. To test processing speed, the researchers administered the Symbol Digit Modalities Test, which required participants to watch a digit with a corresponding abstract geometric shape. In addition to a depression assessment, the participants were also asked to fill out a mood questionnaire. The mood questionnaire was linked to the music that played in the background, which was either Mozart, Mahler, or white noise. The questionnaire asked participants to evaluate the happiness, sadness, and degree of emotion experienced listening to the music on a scale of 1 to 10 (Bottiroli et al., 2014).
The participants were asked to perform the cognitive tests in four different background conditions: no music, white noise, Mozart (positive emotion), and Mahler (negative emotion). The test groups had either white noise or no-music and either Mozart or Mahler, so that each group was exposed to two conditions. In each of the groups, the order of the cognitive tests was counterbalanced across groups. During the background music trial, the background music was played for the duration of the entire task, starting 1 minute before each task, continuing during the task, and ending as soon as the task ended. For the silent condition, participants were asked to be silent for a minute prior to beginning the task (Bottiroli et al., 2014).
Bottiroli et al. examined the results uses a series ANOVA for the background conditions as a within-subjects factor. Looking at episodic memory, they found that background conditions had a significant impact on how the subjects performed on the episodic memory tests. "Pairwise comparisons showed a significant advantage for the Mozart condition over no-music, t (64) = 3.64, and a marginally significant increase over the white noise, t (64)= 2.53, p = 0.014. A significant advantage was also found for the Mahler condition over no-music, t (64) = 4.01, and the white noise condition, t (64) = 3.24. The white noise did not differ from no-music, t (64) = 1.14, as well as the Mozart condition from the Mahler condition, t (64) = 0.39." (Bottiroli et al., 2014). In other words, the presence of music helped the participants in their episodic memory tests, whether the music was positive or negative and the result does not seem attributable to the music simply being background noise, since the experimenters did not obtain the same results with pure background noise.
Semantic memory and episodic memory are distinct and may involve different parts of the brain and different cognitive processes, so Bottiroli et al. anticipated finding different results on the semantic memory tests. "Follow-up analyses revealed a significant advantage of the Mozart condition over no-music, t (64) = 3.02, and white noise, t (64) = 5.21. Performance in the Mahler condition was significantly higher than in the white noise condition, t (64) = 3.36. The Mahler condition neither differ significantly from the no-music condition, t (64) = 1.93, nor from the Mozart condition, t (64)= 2.07" (Bottiroli et al., 2014). What is really fascinating is that the Mozart clearly impacted results more than the Mahler and the Mahler was clearly more impactful than the no-music condition, but the differences in performance level were not significant in either increment block.
It is worth noting that the background noise seemed to impact other cognitive process in addition to memory. On the SDMT, people who listened to Mozart enjoyed a significant advantage over the people listening to Mahler and to white noise, and a non-significant advantage over people who listened to no background music. Although it was not always significant, the Mozart group consistently out-performed the other groups. However, unlike the processing speed task, in the case of episodic and semantic memory tasks both "positive" and "negative" background music conditions induced a significant performance advantage over the silence and white noise conditions, which did not significantly differ in their effect (Bottiroli et al. 2014).
Examined more particularly, and averaged to show the overall impact of the background music on both semantic and episodic memory, the results reveal something interesting about the impact of background noise on memory tasks. Mozart, which is considered a positive music, has an average positive effect with a factor of 1.26. Mahler, which is considered a negative music, has an average positive effect with a factor of 1.18. White noise seems to have an overall negative impact on performance in terms of memory with a factor of .78, which is the same as the no-noise factor (Bottiroli et al. 2014).
Gingko Biloba
The final intervention discussed in this analysis is the use of Ginkgo biloba. Ginkgo biloba has been touted as a memory aid, and, significantly, it has been said to be useful in cases where memory problems are the result of disease or brain degeneration, such as in Alzheimer's and dementia cases. Weinmann et al. conducted a meta-analysis of controlled trials of ginkgo being used to treat patients experiencing Alzheimer's, vascular or mixed dementia, to determine whether ginkgo did have a positive impact on those patients (2010). They expected to find a positive impact because Ginkgo has become a widely accepted herbal remedy to be used in helping fight dementia. In fact, "since 2000, according to the current ATC-classification, Ginkgo biloba special extract is listed in the group of anti-dementia drugs together with cholinesterase inhibitors and memantine" (Weinmann et al., 2010). Despite this listing, the researchers had some questions about the efficacy of the intervention, because many of the studies they found supporting Ginkgo's efficacy and effectiveness were small and had methodological problems that made it difficult, if not impossible, to generalize their results beyond the parameters of each individual study. This has led some to question whether Ginkgo deserves its reputation as a supplement that can improve memory, particularly in vulnerable populations experiencing memory impairment due to Alzheimer's or dementia.
The researcher used a search strategy on several databases:: MEDLINE (January 1, 1966, to August 2008), EMBASE (January 1, 1980 to August 2008), PsycINFO (January 1, 1982, to August 2008), CINAHL (Cumulative Index to Nursing and Allied Health Literature), the Cochrane Database of Systematic Reviews, and the Cochrane Controlled Trials Register (until Issue 3, 2008), with the following search terms: dementia; (senile* AND dement*); Alzheimer*; ((cognit* OR memory* OR mental*) AND (decline OR impair* OR los* OR deteriorat* OR diminish* OR insufficien* OR degenerat*); ginkgo; ginko; gingko; bilobalid*; tebonin; egb 761; li 1370; (clinical AND trial*); random*; placebo*; (controlled AND trial*); (multicent* AND stud*); (comparative AND stud*); follow-up; and (research AND design) (Weinmann et al., 2010). From the search results, the researchers selected controlled clinical trials specifically assessing the effects of Ginkgo on a target population: people who had been diagnosed with Alzheimer's disease, vascular, or mixed dementia. Moreover, the intervention used in those trials had to be a standardized Ginkgo biloba extract, and the study had to meet other criteria for reliability and validity. The extract studied was the standardized extract EGb 761®. "EGb 761® is a dry extract from Ginkgo biloba leaves, extraction solvent: acetone 60% (w/w). The extract is adjusted to 22.0-27.0% ginkgo flavonoids, calculated as ginkgo flavone glycosides and 5.0-7.0% terpene lactones consisting of 2.8-3.4% ginkgolides A, B, C and 2.6-3.2% bilobalid. It contains less than 5 ppm ginkgolic acids" (Weinmann et al., 2010).
While the study has an impact on memory, it is important to keep in mind that the researchers were not specifically examining memory as an isolated factor. Instead they were looking at different outcomes including: cognition, activities of daily living, neuropsychiatric symptoms, and overall quality of life. Cognition, activities of daily living, and overall quality of life are all impacted by the memory loss that accompanies Alzheimer's and dementia. In the evaluation of cognition, patients on Ginkgo experienced an average -.58 to a -.63 difference on the scales used to measure cognition in demention, which would actually reflect a positive change because higher numbers on those scales are indicative of greater dementia scores (Weinmann et al., 2010). For scales of daily living, there was a -.32 difference, and, again, the negative difference reflects a positive change because higher numbers on the scales are indicated of a worse clinical position (Weinmann et al., 2010). Ginkgo did not have a statistically significant impact on neuropsychological or behavior conditions that was stable across studies and some of the studies specifically excluded patients with neuropsychological issues, suggesting that further testing is warranted (Weinmann et al., 2010). Finally, the quality of life improvement was almost three times greater for the Gingko group than for the placebo group (Weinmann et al., 2010).
The researchers concluded that the evidence supports the use of Ginkgo as an intervention for dementia and Alzheimer's. Because neither disorder can be reversed with modern medical interventions, symptomatic treatments are important. To be considered a successful symptomatic treatment, it is important that a drug improve cognitive and/or neuropsychological symptoms. Drugs that delay deterioration are also helpful (Weinmann et al., 2010). The researchers "found a statistically significant advantage of Ginkgo biloba compared to placebo in improving cognition for the whole group of patients with Alzheimer's disease, vascular or mixed dementia. Regarding activities of daily living, there was no significant difference for the whole dementia group. However, in the subgroup of patients with Alzheimer's disease, the advantage of Ginkgo biloba compared to placebo was statistically significant" (Weinmann et al., 2010). These results appeared to be limited to the cognitive symptoms of the disease, however, given that behavioral symptoms often accompany Alzheimer's and dementia, there may be a real reduction in those symptoms if cognition is improved.
Another important consideration that must be examined when looking at medication is the possibility of side effects and drug interactions. "Ginkgo biloba extract seems to be well tolerated with rates of adverse effects and study withdrawals not being different between medication and placebo" (Weinmann et al., 2010). However, it is important to keep in mind that Weinmann et al. specifically looked at studies that utilized the standardized extract EGb 761®, which may differ chemically from other ginkgo extracts and ginkgo-containing products that could have different or more intense side effects. The side effects associated with EGb 761® include: mild gastro-intestinal symptoms, headache, dizziness or allergic skin reactions (Weinmann et al., 2010).
One thing to keep in mind with the studies of Ginkgo is that, at least in Western countries, most of the patients are going to have been exposed to cholinesterase inhibitors. In fact, most of the studies examined specifically allowed study participants to continue their cholinesterase inhibitors during the course of the study. This introduces the idea of an interaction effect; the cholinesterase inhibitors may make the Ginkgo more effective or it may actually interfere with the Ginkgo's efficacy. In fact, what the researchers found seemed to support this notion: they found that there may be "a higher differential efficacy of Ginkgo biloba compared to placebo in a setting with less specialized dementia care and less availability or reimbursement of anti-dementia drugs" (Weinmann et al., 2010). This was because the studies targeting two groups of people without access to high quality memory care had the "highest effect sizes for cognition and activities of daily living outcomes and had extremely low drop-out rates" (Weinmann et al., 2010).
Methodology
In this comprehensive analysis, the author is going to explore the possible interactions between different existing interventions aimed at improving memory and reducing forgetfulness. When multiple interventions are used simultaneously there are several different possible ways for the different interventions to interact. First, the interventions could interact positively together. These interactions could be additive, so that each intervention adds additional benefits to the subject. These interactions could also be multiplicative, so that each percentage of gain adds to the percentage of gain prior to it, greatly increasing the impact of additional interventions. Moreover, there are other possibilities. For example, multiple interventions could actually interfere with one another, lessening the impact of interventions by an amount that is up to, or even exceeds, the expected additional benefit from an added intervention. The author will compare the different possible interactions of multiple interventions, beginning with two different interventions and then adding additional interventions. Moreover, it will examine the possibility of additive, multiplicative, or subtractive interactions.
The goal is to examine which interventions are most likely to be successfully combined in order to reduce forgetfulness. An additional goal is to examine the possible extreme consequences that interference could have on the benefits of another intervention. By looking at the various different potential combinations, the hope is to establish different treatment combinations that would provide the optimum amount of memory enhancement.
Each comparison will begin with a baseline of "1," an arbitrary number for performance that will be the assumed number without any intervention. The number has been chosen to make it possible to compare different types of interventions by looking at the multiplying factors that are the result of those interventions. The interventions listed will show their individual impact on that baseline performance of 1, and what factor would be multiplied or added to the 1 for performance.
Next, interventions will be examined in conjunction with one another, with all of the other interventions examined with the addition of a single intervention. This will show how those factors could impact one another. If two interventions are incompatible, such as the playing of two different types of background music, then they will not be combined with each other. After a two-factor analysis, the impact of three interventions will be examined, to see what type of additional improvement could be anticipated from that addition. The study will stop short of a four-factor analysis, primarily because the fourth intervention studied that shows the most promise was studied in a population suffering from Alzheimer's or other forms of dementia and may not be applicable to a population that is not experiencing the same range and type of memory problems.
Analysis
The analysis begins by isolating the interventions that will be explored throughout the analysis section and examining their individual impact on memory. For the purposes of this study, the researcher will be examining: retrieval practice, retrieval induced forgetting, napping, nocturnal sleep, Mozart, Mahler, white noise, and no noise, and Gingko. The baseline is set at 1, to demonstrate a neutral setting without an intervention. This neutral setting should not be considered an average, but, instead, thought of as the starting point for each individual. In other words, it is an arbitrary baseline of 1, not the result of any type of pre-analysis examination of the hypothetical subject(s) of this analysis.
Memory Interventions
Intervention
Starting Point
Factor
Multiplied
Additive
Retrieval Practice
1
1.77
1.77
+.77
Retrieval Induced
Forgetting
1
.75
.75
-.25
Napping
1
1.27
1.27
+.27
Nocturnal Sleep
1
1.27
1.27
+.27
Mozart
1
1.26
1.26
+.26
Mahler
1
1.18
1.18
+.18
White Noise
1
.78
.78
-.22
No Noise
1
.78
.78
-.22
Ginkgo
1
1.61
1.61
+.61
Table 1: Memory Interventions
What table 1 does is highlight the impact that the different interventions could have on memory and retention. Retrieval practice impacts memory by a factor of 1.77, so that a person who studies to remember something is 77% more likely to remember it than someone who does not engage in retrieval practice. Retrieval induced forgetting impacts memory by a factor of .75, so that a person who engages in a conscious effort to forget information is 25% less likely to remember it. Napping and nocturnal sleep both impact memory by a factor of 1.27, so that a person who naps or sleeps after exposure to new information is 27% more likely to remember it. Listening to Mozart as background music impacts memory by a factor of 1.26, so that a person who listens to Mozart is 26% more likely to remember it than someone with no specific background sounds. Listening to Mahler impacts memory by a factor of 1.18, so that a person who listens to Mahler is 18% more likely to remember than someone with no specific background sound. Listening to white noise and no noise both have negative impacts on memory, with a factor of .78, it means that people who listen to them are 22% less likely to remember. Finally, in patients with dementia, the use of Ginkgo impacted cognition by a factor of 1.61 on cognition scales. While those scales did not specifically target memory, for the purposes of this analysis, they will be treated as a potential 61% improvement in memory.
Beginning with retrieval practice, the paper will focus on the potential interaction between retrieval practice and each of the applicable remaining interventions. Instead of starting at 1, the starting point is set at 1.77, because retrieval practice improved memory of specific items with a 1.77 initial factor:
Retrieval Practice
Intervention
Starting Point
Factor
Multiplied
Additive
Retrieval Induced
Forgetting
1.77
.75
1.3275
1.02
Napping
1.77
1.27
2.2479
2.04
Nocturnal Sleep
1.77
1.27
2.2479
2.04
Mozart
1.77
1.26
2.2302
2.03
Mahler
1.77
1.18
2.0886
1.95
White Noise
1.77
.78
1.3806
1.55
No Noise
1.77
.78
1.3806
1.55
Ginkgo
1.77
1.61
2.8497
2.38
Table 2: Memory Interventions in Conjunction with Retrieval Practice
Table 2 looks at the possible interactions between the 1.77 number from retrieval practice and the interactions from other interventions. It looks at the potential of interactions being purely additive, but also looks at interventions as an increase in percentage. Therefore, retrieval practice used with retrieval induced forgetting could be expected to decrease remembering from 1.77 to somewhere in the 1.02 to 1.3275 range. Napping and nocturnal sleep both impact memory by a factor of 1.27, so that a person who naps or sleeps after exposure to new information is 27% more likely to remember it, which could improve the impact of retrieval practice up to the 2.04 to 2.2479 range. Listening to Mozart as background music impacts memory by a factor of 1.26, so that a person who listens to Mozart is 26% more likely to remember it than someone with no specific background sounds, which could improve the impact of retrieval practice to the 2.03 to 2.2302 range. Listening to Mahler impacts memory by a factor of 1.18, so that a person who listens to Mahler is 18% more likely to remember than someone with no specific background sound, which could improve the impact of retrieval practice to the 1.95 to 2.0886 range. Listening to white noise and no noise both have negative impacts on memory, with a factor of .78, it means that people who listen to them are 22% less likely to remember, which could reduce the impact of retrieval practice to the 1.3806 to 1.55 range. Finally, in patients with dementia, the use of Ginkgo impacted cognition by a factor of 1.61 on cognition scales. While those scales did not specifically target memory, for the purposes of this analysis, they will be treated as a potential 61% improvement in memory. Used with retrieval practice, Ginkgo could improve memory in the 2.38 to 2.8497 range.
Next, the paper examines the interactions of Retrieval Induced Forgetting with the other functions:
Retrieval Induced Forgetting
Intervention
Starting Point
Factor
Multiplied
Additive
Retrieval Practice
.75
1.77
1.3275
1.52
Napping
.75
1.27
.9525
1.02
Nocturnal Sleep
.75
1.27
.9525
1.02
Mozart
.75
1.26
.945
1.01
Mahler
.75
1.18
.885
.93
White Noise
.75
.78
.585
.53
No Noise
.75
.78
.585
.53
Ginkgo
.75
1.61
1.2075
1.36
Table 3: Memory Interventions in Conjunction with Retrieval Induced Forgetting
Table 3 looks at the possible interactions between the .75 starting point for retrieval induced forgetting and the interactions from other interventions. It looks at the potential of interactions being purely additive, but also looks at interventions as an increase in percentage. Therefore, retrieval practice used with retrieval induced forgetting could be expected to decrease remembering from .75 to somewhere in the 1.3275 to 1.52 range. Napping and nocturnal sleep both impact memory by a factor of 1.27, so that a person who naps or sleeps after exposure to new information is 27% more likely to remember it, which could improve the impact of retrieval practice up to the .9525 to 1.02 range. Listening to Mozart as background music impacts memory by a factor of 1.26, so that a person who listens to Mozart is 26% more likely to remember it than someone with no specific background sounds, which could improve the impact of retrieval practice to the .945 to 1.01 range. Listening to Mahler impacts memory by a factor of 1.18, so that a person who listens to Mahler is 18% more likely to remember than someone with no specific background sound, which could improve the impact of retrieval practice to the .885 to .93 range. Listening to white noise and no noise both have negative impacts on memory, with a factor of .78, it means that people who listen to them are 22% less likely to remember, which could reduce the impact of retrieval practice to the .53 to .585 range. Finally, in patients with dementia, the use of Ginkgo impacted cognition by a factor of 1.61 on cognition scales. While those scales did not specifically target memory, for the purposes of this analysis, they will be treated as a potential 61% improvement in memory. Used with retrieval induced forgetting, Ginkgo could impact memory in the 1.2075 to 1.36 range.
Next, the analysis will examine the potential impact of napping when used in conjunction with other interventions. Napping will be examined with the impact of nocturnal sleep in both this analysis and the analysis of nocturnal sleep, although obviously both of them could not occur immediately following exposure to the stimuli, and thus one would not anticipate the full effect of either napping or nocturnal sleep on the outcome:
Napping
Intervention
Starting Point
Factor
Multiplied
Additive
Retrieval Practice
1.27
1.77
2.2479
2.04
Retrieval Induced
Forgetting
1.27
.75
.9525
1.02
Nocturnal Sleep
1.27
1.27
1.6129
1.54
Mozart
1.27
1.26
1.6002
1.53
Mahler
1.27
1.18
1.4986
1.45
White Noise
1.27
.78
.9906
1.05
No Noise
1.27
.78
.9906
1.05
Ginkgo
1.27
1.61
2.0447
1.88
Table 4: Memory Interventions in Conjunction with Napping
Table 4 looks at the possible interactions between the 1.27 starting point for napping and the interactions from other interventions. It looks at the potential of interactions being purely additive, but also looks at interventions as an increase in percentage. Therefore, napping used with retrieval practice could result in changes in the 2.04 to 2.2479 range. Napping used with retrieval induced forgetting could be expected to decrease remembering to the .9525 to 1.02 range. Napping and nocturnal sleep both impact memory by a factor of 1.27, so that a person who naps or sleeps after exposure to new information is 27% more likely to remember it, which means that napping and nocturnal sleep together could result in a 1.54 to 1.6129 range. Listening to Mozart as background music impacts memory by a factor of 1.26, so that a person who listens to Mozart is 26% more likely to remember it than someone with no specific background sounds, which could improve the impact of napping to the 1.53 to 1.6002 range. Listening to Mahler impacts memory by a factor of 1.18, so that a person who listens to Mahler is 18% more likely to remember than someone with no specific background sound, which could improve the impact of napping to the 1.45 to 1.4986 range. Listening to white noise and no noise both have negative impacts on memory, with a factor of .78, it means that people who listen to them are 22% less likely to remember, which could reduce the impact of napping to the .9906 to 1.05 range. Finally, in patients with dementia, the use of Ginkgo impacted cognition by a factor of 1.61 on cognition scales. While those scales did not specifically target memory, for the purposes of this analysis, they will be treated as a potential 61% improvement in memory. Used with napping, Ginkgo could impact memory in the 1.88 to 2.0447 range.
Because nocturnal sleep has the same type of impact as napping on memory, the table for nocturnal sleep is virtually identical to the table for napping:
Nocturnal Sleep
Intervention
Starting Point
Factor
Multiplied
Additive
Retrieval Practice
1.27
1.77
2.2479
2.04
Retrieval Induced
Forgetting
1.27
.75
.9525
1.02
Napping
1.27
1.27
1.6129
1.54
Mozart
1.27
1.26
1.6002
1.53
Mahler
1.27
1.18
1.4986
1.45
White Noise
1.27
.78
.9906
1.05
No Noise
1.27
.78
.9906
1.05
Ginkgo
1.27
1.61
2.0447
1.88
Table 5: Memory Interventions in Conjunction with Nocturnal Sleep
Table 5 looks at the possible interactions between the 1.27 starting point for nocturnal sleep and the interactions from other interventions. It looks at the potential of interactions being purely additive, but also looks at interventions as an increase in percentage. Therefore, nocturnal sleep used with retrieval practice could result in changes in the 2.04 to 2.2479 range. Nocturnal sleep used with retrieval induced forgetting could be expected to decrease remembering to the .9525 to 1.02 range. Napping and nocturnal sleep both impact memory by a factor of 1.27, so that a person who naps or sleeps after exposure to new information is 27% more likely to remember it, which means that napping and nocturnal sleep together could result in a 1.54 to 1.6129 range. Listening to Mozart as background music impacts memory by a factor of 1.26, so that a person who listens to Mozart is 26% more likely to remember it than someone with no specific background sounds, which could improve the impact of nocturnal sleep to the 1.53 to 1.6002 range. Listening to Mahler impacts memory by a factor of 1.18, so that a person who listens to Mahler is 18% more likely to remember than someone with no specific background sound, which could improve the impact of nocturnal sleep to the 1.45 to 1.4986 range. Listening to white noise and no noise both have negative impacts on memory, with a factor of .78, it means that people who listen to them are 22% less likely to remember, which could reduce the impact of nocturnal sleep to the .9906 to 1.05 range. Finally, in patients with dementia, the use of Ginkgo impacted cognition by a factor of 1.61 on cognition scales. While those scales did not specifically target memory, for the purposes of this analysis, they will be treated as a potential 61% improvement in memory. Used with nocturnal sleep, Ginkgo could impact memory in the 1.88 to 2.0447 range.
Next, the paper analyses the potential interaction between Mozart as background music and the other interventions, because only one background sound can be utilized at a time, for the impact of background sounds, this study will not analyze the potential interaction between multiple background sounds:
Mozart
Intervention
Starting Point
Factor
Multiplied
Additive
Retrieval Practice
1.26
1.77
2.2302
2.03
Retrieval Induced
Forgetting
1.26
.75
.945
1.01
Napping
1.26
1.27
1.6002
1.53
Nocturnal Sleep
1.26
1.27
1.6002
1.53
Ginkgo
1.26
1.61
2.0286
1.87
Table 6: Memory Interventions in Conjunction with Mozart
Table 6 looks at the possible interactions between the 1.26 starting point for Mozart and the interactions from other interventions. It looks at the potential of interactions being purely additive, but also looks at interventions as an increase in percentage. Therefore, Mozart used with retrieval practice could result in changes in the 2.03 to 2.2302 range. Mozart used with retrieval induced forgetting could be expected to decrease remembering to the .945 to 1.01 range. Napping and nocturnal sleep both impact memory by a factor of 1.27, so that a person who naps or sleeps after exposure to new information is 27% more likely to remember it, which means that napping or nocturnal sleep together with Mozart could 1.53 to 1.6002 range. Finally, in patients with dementia, the use of Ginkgo impacted cognition by a factor of 1.61 on cognition scales. While those scales did not specifically target memory, for the purposes of this analysis, they will be treated as a potential 61% improvement in memory. Used with Mozart, Ginkgo could impact memory in the 1.87 to 2.0286 range.
The next background noise to be examined is Mahler, which was characterized as a negative background noise. As with Mozart, the examination of Mahler will not involve looking at other potential sources of background noise because of the presumption that people can only be exposed to a single type of background noise at a time. The introduction of white noise would change the background noise environment.
Mahler
Intervention
Starting Point
Factor
Multiplied
Additive
Retrieval Practice
1.18
1.77
2.0886
1.95
Retrieval Induced
Forgetting
1.18
.75
.885
.93
Napping
1.18
1.27
1.4986
1.45
Nocturnal Sleep
1.18
1.27
1.4986
1.45
Ginkgo
1.18
1.61
1.8998
1.79
Table 7: Memory Interventions in Conjunction with Mahler
Table 7 looks at the possible interactions between the 1.18 starting point for Mahler and the interactions from other interventions. It looks at the potential of interactions being purely additive, but also looks at interventions as an increase in percentage. Therefore, Mahler used with retrieval practice could result in changes in the 1.95 to 2.0886 range. Mahler used with retrieval induced forgetting could be expected to decrease remembering to the .885 to .93 range. Napping and nocturnal sleep both impact memory by a factor of 1.27, so that a person who naps or sleeps after exposure to new information is 27% more likely to remember it, which means that napping or nocturnal sleep together with Mahler could result in the 1.45 to 1.4986 range. Finally, in patients with dementia, the use of Ginkgo impacted cognition by a factor of 1.61 on cognition scales. While those scales did not specifically target memory, for the purposes of this analysis, they will be treated as a potential 61% improvement in memory. Used with Mahler, Ginkgo could impact memory in the 1.79 to 1.8998 range.
Next, the paper analyses the potential interaction between white noise as background music and the other interventions, because only one background sound can be utilized at a time, for the impact of background sounds, this study will not analyze the potential interaction between multiple background sounds.
White Noise
Intervention
Starting Point
Factor
Multiplied
Additive
Retrieval Practice
.78
1.77
1.3806
1.54
Retrieval Induced
Forgetting
.78
.75
.585
.53
Napping
.78
1.27
.9906
1.05
Nocturnal Sleep
.78
1.27
.9906
1.05
Ginkgo
.78
1.61
1.2558
1.39
Table 8: Memory Interventions in Conjunction with White Noise
Table 8 looks at the possible interactions between the .78 starting point for white noise and the interactions from other interventions. It looks at the potential of interactions being purely additive, but also looks at interventions as an increase in percentage. Therefore, white noise used with retrieval practice could result in changes in the 1.3806 to 1.54 range. White noise used with retrieval induced forgetting could be expected to decrease remembering to the .53 to .585 range. Napping and nocturnal sleep both impact memory by a factor of 1.27, so that a person who naps or sleeps after exposure to new information is 27% more likely to remember it, which means that napping or nocturnal sleep together with white noise could be in the .9906 to 1.05 range. Finally, in patients with dementia, the use of Ginkgo impacted cognition by a factor of 1.61 on cognition scales. While those scales did not specifically target memory, for the purposes of this analysis, they will be treated as a potential 61% improvement in memory. Used with white noise, Ginkgo could impact memory in the 1.2558 to 1.39 range.
The paper also examines the impact of silence as background noise. While it may seem like silence is the default, the reality is that real life scenarios rarely involve silence; there is generally a type of background noise. Testing scenarios in life may be silent, with the presumption that the silence eliminates distractions and helps the cognitive process, but the memory results from silence seem to suggest a counterintuitive result and that silence, itself, can serve as interference in the cognitive process:
Silence
Intervention
Starting Point
Factor
Multiplied
Additive
Retrieval Practice
.78
1.77
1.3806
1.54
Retrieval Induced
Forgetting
.78
.75
.585
.53
Napping
.78
1.27
.9906
1.05
Nocturnal Sleep
.78
1.27
.9906
1.05
Ginkgo
.78
1.61
1.2558
1.39
Table 9: Memory Interventions in Conjunction with Background Silence
Table 9 looks at the possible interactions between the .78 starting point for background silence and the interactions from other interventions. It looks at the potential of interactions being purely additive, but also looks at interventions as an increase in percentage. Therefore, silence used with retrieval practice could result in changes in the 1.3806 to 1.54 range. Background silence used with retrieval induced forgetting could be expected to decrease remembering to the .53 to .585 range. Napping and nocturnal sleep both impact memory by a factor of 1.27, so that a person who naps or sleeps after exposure to new information is 27% more likely to remember it, which means that napping or nocturnal sleep together with background silence could be in the .9906 to 1.05 range. Finally, in patients with dementia, the use of Ginkgo impacted cognition by a factor of 1.61 on cognition scales. While those scales did not specifically target memory, for the purposes of this analysis, they will be treated as a potential 61% improvement in memory. Used with background silence, Ginkgo could impact memory in the 1.2558 to 1.39 range.
The final two-factor table focuses on the use of Ginkgo biloba as a memory aid. It is critical to keep in mind that the studies used in this comprehensive analysis examined patients with dementia, so that these results should not be translated to a normal population:
Ginkgo Biloba
Intervention
Starting Point
Factor
Multiplied
Additive
Retrieval Practice
1.61
1.77
2.8497
2.38
Retrieval Induced
Forgetting
1.61
.75
1.2075
1.36
Napping
1.61
1.27
2.0447
1.88
Nocturnal Sleep
1.61
1.27
2.0447
1.88
Mozart
1.61
1.26
2.0286
1.87
Mahler
1.61
1.18
1.8998
1.79
White Noise
1.61
.78
1.2558
1.39
No Noise
1.61
.78
1.2558
1.39
Table 10: Memory Interventions Used in Conjunction with Ginkgo Biloba
Table 10 looks at the possible interactions between the 1.62 number from Ginkgo and the interactions from other interventions. It looks at the potential of interactions being purely additive, but also looks at interventions as an increase in percentage. Therefore, Ginkgo used with retrieval practice could result in a range from 2.38 to 2.8479. Ginkgo used with retrieval induced forgetting could be expected to decrease remembering from 1.2075 to 1.36 range. Napping and nocturnal sleep both impact memory by a factor of 1.27, so that a person who naps or sleeps after exposure to new information is 27% more likely to remember it, which could improve the impact of retrieval practice up to the 1.88 to 2.0447 range. Listening to Mozart as background music impacts memory by a factor of 1.26, so that a person who listens to Mozart is 26% more likely to remember it than someone with no specific background sounds, which could improve the impact of Ginkgo to the 1.87 to 2.0286 range. Listening to Mahler impacts memory by a factor of 1.18, so that a person who listens to Mahler is 18% more likely to remember than someone with no specific background sound, which could improve the impact of Gingko to the 1.79 to 1.8998 range. Listening to white noise and no noise both have negative impacts on memory, with a factor of .78, it means that people who listen to them are 22% less likely to remember, which could reduce the impact of Ginkgo to the 1.2558 to 1.39 range.
What is interesting is that both Mozart and nocturnal sleep have positive impacts on memory and do not require active participation or intervention by the participants. In fact, they could be used as interventions without impacting other treatment modalities in any way. Therefore, looking at how the combination of Mozart and nocturnal sleep impact the other factors could help highlight how three or more factors could interact to show improvement. The range for Mozart and nocturnal sleep is between 1.53 and 1.6002. Therefore, the results will be presented as ranges
Mozart and Nocturnal Sleep
Intervention
Starting Point
Factor
Multiplied
Additive
Retrieval Practice
1.53-1.6002
1.77
2.7081-2.8323
3.3-3.37
Retrieval Induced
Forgetting
1.53-1.6002
.75
1.1475-1.2002
1.28-1.35
Napping
1.53-1.6002
1.27
1.9431-2.0323
1.8-1.87
Ginkgo
1.53-1.6002
1.61
2.4633-2.5763
2.14-2.21
Table 11: Memory Interventions in Conjunction with Mozart and Nocturnal Sleep
Table 11 presents the potential ranges of three interventions, beginning with a base of Mozart as background music and a period of nocturnal sleep prior to the testing experience. The combination of Mozart, nocturnal sleep, and retrieval practice could yield results somewhere in the 2.7081 to 3.37 range. The combination of Mozart, nocturnal sleep, and retrieval induced forgetting could yield results in the 1.1475-1.35 range. The combination of Mozart, nocturnal sleep, and napping could yield results in the 1.8 to 2.0323 range. Finally, the combination of Mozart, nocturnal sleep, and Ginkgo could yield results in the 2.14 to 2.5763 range.
Of course, given that napping and nocturnal sleep show similar results, one must also consider the interaction of napping, and Mozart on the other treatment modalities. The range for Mozart and napping is between 1.53 and 1.6002. Therefore, the results will be presented as ranges:
Mozart and Napping
Intervention
Starting Point
Factor
Multiplied
Additive
Retrieval Practice
1.53-1.6002
1.77
2.7081-2.8323
3.3-3.37
Retrieval Induced
Forgetting
1.53-1.6002
.75
1.1475-1.2002
1.28-1.35
Nocturnal Sleep
1.53-1.6002
1.27
1.9431-2.0323
1.8-1.87
Ginkgo
1.53-1.6002
1.61
2.4633-2.5763
2.14-2.21
Table 12: Memory Interventions in Conjunction with Mozart and Napping
Table 12 presents the potential ranges of three interventions, beginning with a base of Mozart as background music and a period of napping prior to the testing experience. The combination of Mozart, napping, and retrieval practice could yield results somewhere in the 2.7081 to 3.37 range. The combination of Mozart, napping, and retrieval induced forgetting could yield results in the 1.1475-1.35 range. The combination of Mozart, nocturnal sleep, and napping could yield results in the 1.8 to 2.0323 range. Finally, the combination of Mozart, nocturnal sleep, and Ginkgo could yield results in the 2.14 to 2.5763 range.
Discussion
For the purposes of this discussion, it is critical to understand the use of the false baseline. The number 1 was chosen to make both multiplication and addition easier and better able to reflect the potential interaction between different interventions, not to suggest that the participants of the various studies investigated throughout the course of this research somehow scored a baseline of 1 on any test of memory or cognitive function. Furthermore, the improvements shown by other interventions are not all based on that single number baseline. Instead, many of them looked at specific tests and assessed the efficacy of their intervention based on those test results. As a result, it is important to keep in mind that the numerical ranges given by combining the different interventions should not be translated to percentages of improvement. Instead, they have been translated to a single numerical system in order to provide a means of comparing and contrasting the interventions and to provide guidance for future research into the interventions.
When placed into a single system, it quickly became clear that some interventions had a significant potential for impacting memory, which was not replicated by other interventions. For example, retrieval practice, which is akin to what many people do when attempting to memorize data, had a factor of 1.77, which was the highest factor discussed in the paper. This should come as no surprise to anyone who has ever memorized any information, because we naturally use repetition to memorize information. After all, retrieval practice, which involves both repetition and categorization, is how most people transfer information from their short-term to long-term memories. There is some understanding that working memory plays a role in this process, although how working memory and other cognitive processes interact with short-term and long-term memory to move information from one to the other is still not fully understood. What is understood is that the more times a person is exposed to information and accesses that information in the short-term memory context, the more likely that information is to make it into the person's long-term memory.
However, it is important to keep in mind that retrieval practice, while highly effective, is not always applicable in all scenarios. Retrieval practice involves directing attention at particular pieces of information in order to keep that information in short-term memory or move that information into long-term memory. However, people do not always know what information they should focus on when exposed to a memory; this is particularly true in a non-academic or memorization setting. In naturally-occurring settings, people may not know what to focus on when storing memories, so that they cannot then engage in retrieval practice for that information. Therefore, the efficacy of retrieval practice may be more practical in semantic memory scenarios than in episodic memory scenarios.
What is even more interesting is that directed forgetting in the form of retrieval induced forgetting had such a dramatic impact on people's ability to remember information after exposure. It is already well understood that the average person simply cannot pay attention to all of the surrounding stimuli in a scenario. Therefore, people assign importance to different features and focus on those features when memorizing events. However, the choice of what to remember is frequently a subconscious one, so that people may not actively choose what to remember and what not to remember. Knowing that retrieval induced forgetting can actually impact memory, even if only what is generally known as short-term or working memory, may have therapeutic applications.
The first interesting application would be to extend upon the forgetting that is already a significant part of behavioral therapies. After all, simple extinction work focuses on trying to get people to reduce or eliminate associations between certain triggers and behaviors. The idea is to create a new, stronger association that supersedes the association between the trigger and the negative behavior. This concept applies to all varieties of extinction therapy, whether the person is trying to end a simple bad habit or whether the person is working to end an addiction and is trying to condition a different response to the trigger. It also works at a basic operant conditioning level. The person has already learned one response to the triggering behavior and anticipates the reward that comes with that response. When avoiding the behavior, generally the person avoids getting the reward response, which can create anxiety and discomfort in the person. For this reason, many people avoid behavioral therapy techniques and repeatedly engage in behaviors that reinforce existing bad habits.
Of course, sometimes extinction-base behavioral therapies substitute other rewards in that scenario to try to establish different pathways for rewards, but they are still fighting against the known relationship of stimulus-reward. If directed forgetting is possible in the short-term, one has to wonder if directed forgetting is possible in the long-term. Could extinction therapies be expanded in a way that made them actually target the existence of known pathways and not just foster the creation of new pathways? If so, the notion would be revolutionary in terms of the treatment of many modern disorders such as phobias, addictions, and even the stemming associated with Autism spectrum disorders.
The potential memory applications for retrieval induced forgetting are also significant. Memory loss is often times not memory loss at all, but actually memory confusion. Many elderly people have a problem with recalling the timeline of events that occurred or have a problem differentiating between events that actually occurred and similar events that did not actually occur. Rather than being unable to access memories, they seem to have a problem processing those memories and putting them in an order that makes them useful. While researchers have not pinpointed the cause of this problem, at first blush it appears to be an issue with the working memory. After all, one of the roles of the working memory is to allow the long-term and short-term memories to interface in a meaningful manner. If the working memory is no longer able to provide a valid directory for the contents of the long-term memory, then the long-term memory becomes virtually useless as far as providing guidance and direction in daily decision making.
However, if an intervention could be created that taught the working memory how to forget irrelevant information, then the working memory might be better-able to access the correct information in long-term memory for use in short-term mental processing. The challenge is to develop a targeted forgetting method that works on the long-term memory or at least on how the working memory accesses the long-term memory. Whether this is even possible is an open question, but one worth investigating since it is clear that, at least for short-term memory, directed forgetting is a possibility.
The role that sleep plays in memory is very intriguing as well and brings into question some of the norms that people have assimilated about thought and memory. The research clearly demonstrates better retention of facts is people are given a period of time to sleep after exposure to the facts, whether that sleep comes in the form of a nap or in the form of nocturnal sleep. Moreover, the actual sleep seems critical to the memory process; down time did not serve the same critical memory function for the study participants as actual sleep did. Of course, the modern educational paradigm does not provide napping or sleeping opportunities immediately following exposure to new information; instead, school begins in the morning and students attend school all day, have afternoons that probably do not feature naps, and then go to bed at night, hours removed from the exposure to new information. This scenario completely fails to take advantage of the natural reinforcing power of sleep. A better paradigm, in terms of memory, would be to follow up every period of learning with a sleep opportunity, to reinforce what was taught. Of course, such a paradigm has obvious problems: people sleep at different times; the school day would last all day if people were given nap opportunities after each class; and school would need to run well into the evening hours. In primary education, the scenario would be unworkable.
However, knowing the role that sleep, including napping, can play in memory retention, it would be possible for a college-level student to tailor his or her schedule in order to provide napping opportunities throughout the day, thus maximizing his or her ability to retain information. It might not be practical throughout the course of an entire education, but might be an important and helpful option in semesters containing classes that involve a lot of memorization. Even if the nap time could not be scheduled after each course, it could be schedule after particularly daunting courses.
Of course, it does not require an entire shift of the educational paradigm to take advantage of the role that sleep can play in reinforcing memories. To take advantage of this, it is not critical that the first exposure to the information occur prior to sleep, but only that an exposure to the information occur just prior to sleep. Therefore, to incorporate this into daily living, a student or that student's family could institute a nightly review of material to occur just prior to bedtime. This nightly review would provide a learning opportunity that immediately preceded scheduled sleeping time, which would hopefully reinforce the information and give the learner an opportunity to capitalize on the sleep advantage. Given that sleep appears to boost memory by a significant percentage and that adding a nightly review of material one hopes to memorize is not a daunting or difficult task, it certainly seems as if it is worth the effort to see if it works for each individual.
It was also fascinating to see the role that background noise plays in memory. The results clearly demonstrated that background music, whether given a positive or negative emotional rating by people, plays a significant role in aiding memory. Moreover, this role went beyond memory specifically and seemed to enhance all cognitive tasks. Again, one must reflect upon the school paradigm, where silence is considered paramount to the testing experience. Of course, silence is rarely silent. One can hear other students making noise, which seems as if it would be distracting. While background music is obviously audible, its patterns and repetition would seem to prevent it from being distracting in the same way that normal ambient room sounds are distracting. This alone seems as if it would improve the ability to concentrate, therefore improving cognitive functions, including memory.
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