Memory concepts and psychological mechanisms

Memory is one of the most complex and one of the most essential functions of the human brain. Without the ability to create, process, and retrieve memories, anything that required long-term planning or the building up of information would be absolutely impossible. Memory is in many ways responsible not only for the actions we are capable of undertaking, but even for our conceptions of ourselves -- that is, our actual sense of personality and identity is almost wholly dependent on our memories, and our ability to create new memories. This can be established with just a brief and cursory examination of the basic concept of identity. The decisions an individual makes on a daily basis, their tastes, and their expectations are all built on their prior experiences. If a certain food tasted bad in the past, the individual assumes it will have an unpleasant taste in future instances; if a certain situation led to pain or discomfort, most individuals would be likely to avoid that situation whenever possible.

Without the memories of these past instances, the myriad of choices that make up a personality would be completely uninfluenced by anything other than immediate circumstances, and there would be no subjective point of reference -- i.e. personality or identity -- from which these decisions were being made. Memory, then, could be said to be what makes us human, and what makes us individuals. If all human beings had experiences that were absolutely identical in every detail, it could be argued that all human beings would then have the same personality, and the same reaction to current and future events. There are, of course, other subtle factors that play into the development and creation of a personality and sense of identity, but memory can definitely be considered to be the main constituent, if not the most direct, of the various factors and forces that contribute to an individual's personality and identity.

Due to the extreme importance of memory as a factor in the development of personality, it should come as no surprise that it is a highly complex psychological feature. To simplify and clarify our understanding of memory, scientists and other researchers have determined that there are three distinct types or stages in memory -- sensory memory, short-term or working memory, and long-term memory. A related though slightly different framework developed for the understanding of memory divides the process of developing useful memories into the stages of encoding, storage, and retrieval, which are the three basic functions and mechanisms in which the brain acts on memory. An examination of these two frameworks and the various constituent parts and/or stages that comprise them will lead to a clear background and overview understanding of the phenomenon of memory and its importance.

To begin with, an examination of the differences between sensory memory, short-term or working memory, and long-term memory is essential to a deeper understanding of memory. To suggest that these three types and/or stages of memory development re actually distinct and separable is perhaps disingenuous, as in reality the three interact and influence each other in highly intricate and profound ways. This being said, it is still easier to grasp the different neurological and psychological mechanisms that are at work in the creation and implementation of useful memories when the three stages/types are examined separately, as they do all work by different means, and also have somewhat different results and applications.

Sensory memory is relatively simple, and its function and purpose can largely be intuited from its name -- this type of memory deals with the storage and retrieval of sensory stimuli, or the ability to recall visual and auditory events and specific details after the stimulus has passed (Squire & Kandel 1999). This is where virtually all memory starts; there can simply be no formation of a memory without some initial input in the form of sensory stimuli -- the whiff of the aroma of a new food cooking, the first time a song is heard, the initial reading of a certain piece of information, etc. -- all of these are necessary before any further thought or memory construction regarding the smell, song, or fact is possible (Squire & Kandel 1999). This fact should be fairly self-evident, and explains why sensory memory is considered the simplest and most basic type of memory. This does not mean that it is unimportant, however, in fact far from it. As a sensory memory the initial type of memory formed in response to any external stimulus, the formation of a sensory memory is absolutely essential to the formation of both short-term and long-term memories (Squire & Kandel 1999).

Short-term memory, in turn, is necessary for the formation of long-term memories, and is also something of an intermediary step between sensory memory and long-term memory (Squire & Kandel 1999). This does not mean that short-term memory serves no function in and of itself, however; the fact that short-term memory is also known as working memory should be an indicator that this is not the case. Short-term memory is that type of memory which human beings are able to easily (almost instantly) access for use in everyday tasks and the operations of life (Squire & Kandel 1999). This occurs due to minute physical changes in synapses and neurons as they respond to stimuli, and develop temporary pathways for nerve impulses that facilitate their faster activation when various stimuli are repeated (Kandel 2007).

These temporary changes to synapses and neurons create useful pathways for the conscious and unconscious functioning of memory in given tasks, and in response to given stimuli, but this is not where the usefulness of short-term memories ends. They are also essential in allowing for the creation of long-term memories, which serve their own vital functions in the human psyche (Kandel 2007). The exact, detailed process by which the short-term pathways initially formed in the creation of memory are converted into long-term memories is not completely understood, but evidence shows that it actually has something to do with the synthesis of new proteins, which actually affect the genetic structure of the synapses and neurons involved in the memory (Kandel 2007). This leads to changes that are similar to those that occur in short-term memories (in fact, they often grow out of the same channels), but the genetic change to the cells involved makes these changes more permanent (Kandel 2007).

The processes of encoding, storing, and retrieving memories are closely related to the formation of sensory, short-term, and long-term memories, and can perhaps be better understood after an explanation of these three types of memory formation. The encoding process takes place as described above, moving through sensory and short-term memory to long-term memory, if the pathway is used enough (Squire & Kandel 1999). Storage is also largely the same; memories exist either as the short-term changes in neural pathways and synapses, or in the permanent changes made through protein synthesis and subtle genetic changes that result in the formation of long-term memories (Squire & Kandel, 1999; Kandel 2007). Retrieval, however, is a process that is far more complicated and is only now beginning to be understood.

In our experiment, the ability to recognize partial words (i.e. words with letters missing) is examined for its relationship, if any, to the memory of having seen the words previously in a list. The purpose of this experiment is to determine the role that memory plays in word and pattern recognition, and to test the effectiveness of memory in enabling people to absorb and process information. This could help lead to a better understanding of the role memory plays in learning, which could in turn lead to better models and frameworks for teaching, as well as adding to the less immediately practical but still vital body fo knowledge concerning the working of memory and the human brain in general. because this experiment is specifically related to the knowledge of words, but presents them in unfamiliar (i.e. incomplete) ways, it draws on various types of memory and recognition, relying on the long-term declarative memory of words in general, and the short-term memory of the words from the list.

These words were kept long enough to ensure that they could still be recognizable and exclusionary of other words even when letters were removed to make the words incomplete. To aid in consistency and to standardize recognition, words both on the list and when presented individually with letters missing were printed entirely in upper-case block letters in a uniform font. Examples of the words used in this experiment include BEAUTIFUL, BACHELOR, GAZETTE, PHARAOH, ROTUNDA, THEOREM, and WARRANTY, among many others. The object was to choose words that would be familiar enough to most speakers and readers of English, without making the words either so common or so unique that they would be easily recognized with letters missing, but that at the same time would still be recognizable.