Memory development and learning across the human lifespan

Neonatal Developmental to Memory Loss Stage

The centrality of memory to normal human functioning has long been the focus of ongoing research, and a great deal of understanding has been gained concerning the organic processes that are involved in retaining and recalling information during different stages of life. To determine what has been learned about learning and memory across the lifespan, this paper provides a review of the relevant peer-reviewed and scholarly literature, followed by a summary of the research and important findings in the conclusion.

Cognition of Learning and Memory

Humans begin to learn before they are even born, and the learning process continues throughout the lifespan, a process that is made possible by their short- and long-term memories. In this regard, Pressley and Schneider (1999) report that, "In contrast to short-term memory is a long-term store that contains virtually everything that the person knows. This long-term store contains knowledge of procedures (e.g., strategies) that can operate on information in short-term storage" (p. 7). Indeed, some authorities even maintain that memory is not only essential to the encoding, storage, and retrieval of information, but is a fundamental requirement of human cognition in all its forms (Richardson, Engle, Hasher, Logie, Stoltzfus & Zacks, 1999). Although experimental approaches exist that have been proven effective in contributing to the understanding of these processes, the actual functioning of human learning and memory remains better described than understood in many instances.

The Developing Memory: Birth to Old Age

A great deal of research was conducted during the latter half of the 20th century to determine how humans begin the learning process and continue through their lifespans (Pressley & Schneider, 1999). Although the studies to date have resulted in some mixed findings, there is a growing consensus that very young children begin to develop memory early on, with some distinct differences in learning taking place by the time they reach age 3 years (Pressley & Schneider, 1999). As people reach puberty and early adulthood, their memories continue to develop by drawing on previous experiences and formulating coping strategies that can be used in novel events (Pressley & Schneider, 1999). Although many people remain lucid with good working and long-term memories and are capable of learning until they die, others suffer from various age-related disorders that adversely affect their memories (Pressley & Schneider, 1999).

Conditioning and Skill Learning

By age 3 to 4 years, humans experience conditioning and demonstrate skill learning, but memorization remains lacking; by the time they are 5 years old, though, humans tend to exhibit the ability to establish goals about what they want to remember and seek out ways to do so (Pressley & Schneider, 1999). Many 6- and 7-year-olds have acquired the faculties needed to recall objects and images, but even these advances are characterized by simple repetition used to enhance memorization (Pressley & Schneider, 1999). Significant advances in conditioning and skill learning are achieved by the time adolescence is reached, with substantial development taking place during this period and young adulthood, setting the stage of adult learning (Pressley & Schneider, 1999).

Development of Episodic and Semantic Memory

During the early 1970s, Tulving proposed that explicit memory in humans can be differentiated into that episodic memory and semantic memory, which Tulving believed were completely different systems (Baddeley, Kopelman & Wilson, 2002). According to Baddeley and his associates, "The term 'episodic memory' refers to the capacity to recollect specific incidents from the past, remembering incidental detail that allows [people] to relive the event or, as Tulving phrases it, to 'travel back in time.'" (2002, p. 8). By contrast, Baddeley et al. note that semantic memory is the "generic knowledge of the world; knowing the meaning of the word 'salt,' for example, or its French equivalent, or its taste. Knowledge of society and the way it functions, and the nature and use of tools are also part of semantic memory, a system that [people] tend to take for granted" (2002, p. 8).

Summary: Learning and Memory across the Lifespan

Learning and memory begin to take shape early on in human life, with the underlying processes gaining sophistication and breadth as people mature. Young children demonstrate the ability to learn and remember, but the strategies they use to do so are less efficient compared to later in life. Absent organic conditions that can adversely affect the learning and memory functions, humans should be capable of acquiring new information and retaining it as long as they live.

Brain Substrates

The study of brain substrates of memory and the cognitive organization of memory has been facilitated in recent years by innovations in methods that can be used to measure brain activity to identify how humans acquire information and retain it (Medin, 2001). Because the scope and amount of learning that take place as measured by these innovations, they have contributed much to understanding the genetic basis of learning and memory (Eichenbaum, 1997) which is discussed further below.

The Genetic Basis of Learning and Memory

Although all humans are unique, they all share a common gene pool and therefore the same basic abilities to learn and remember. In this regard, Welch, Cleckley and McClure report that, "There seems to be little evidence to assume that one ethnic group is genetically different from other ethnic groups. There is only one race of humans, since not one biological trait or feature serves to make persons of one ancestry biologically incompatible with persons from another ancestry" (1999, p. 94). These are important consideration for educators because they dispel any notions of one ethnicity having a superior capability to learn and remember (Welch et al., 1999).

Neurons and Synapses in the Developing Brain

The connection of neurons and new synapses in the human brain is required for memory processes and cognition to develop, but the process is somewhat cumulative and mutually reinforcing over time (Pressley & Schneider, 1999). Newly formed networks in the brain help to create the framework in which new memories are stored and accessed, a process that also accelerates as people grow and mature (Pressley & Schneider, 1999).

Gender Difference in Brain and Behavior

Despite a growing body of knowledge, researchers remain divided concerning how gender affects brain functioning and human behavior (Notman & Nadelson, 1999). The debate over whether young children acquire their gender-specific behaviors as a result primarily of nature vs. nurture also continues (Notman & Nadelson, 1999). In fact, a wide range of differences in culture, technology and socioeconomic organization also play a role in gender-related behaviors that may or may not be directly associated with gender-related differences in the brain (Notman & Nadelson, 1999).

The Brain from Neonatal to Old Age

The brains of neonates are differentiated from brains of older humans by being smoother surface tissues that wrinkle with the development of synapse formation during the acquisition and retention of information (Kolb, 1995).

Summary: Observing Brain and Structure and Function

Although all humans are unique, the research showed that everyone shares a common genetic basis for learning and remembering new information. As neuron activity and synapse formation accelerate during later life, learning and memory are facilitated. There may be some gender-based difference in brain and behavior, but this remains understudied and unclear at this time.

Clinical Perspective

From a clinical perspective, determining how people learn and remember new information represents a timely and valuable enterprise, particularly with a rapidly aging population that is experiencing unprecedented prevalence levels of debilitating conditions such as Alzheimer's disease.

Down's Syndrome

Down's syndrome is among a wide range of chromosomal abnormalities that affect about 6 out of every 1,000 births that can cause developmental problems across the lifespan (Heyman & Henrikson, 2001).

Alzheimer's Disease

Currently, Alzheimer's disease represents the most common cause of dementia and affects almost 4 million people in the United States alone (Handy, Turnbull, Edwards & Lancaster, 1998). The number of people afflicted by Alzheimer's disease is projected to increase significantly by the mid-21st century, when almost 15 million people are expected to suffer from the condition (Handy et al., 1998). It is important to note that Alzheimer's disease is not an age-related condition per se; however, elderly are predisposed to the condition and it therefore affects predominantly elderly people (Handy et al., 1998).

Treating (and Preventing) Alzheimer's

A number of treatments for the symptoms of Alzheimer's disease are available, but there is no cure or prevention currently available for the condition (Handy et al., 1998).

Summary: A connection between Down's Syndrome and Alzheimer's Disease?

Because so little is known about the causes of Alzheimer's disease and the fact that human are notoriously difficult subjects to study over the long-term, there may be an unrecognized connection between Down's syndrome and Alzheimer's disease that merits further investigation.

Conclusion

The research showed that the human brain begins to learn early on, and the process accelerates as neural networks are created and synaptic activity increases. Very young children exhibit the ability to learn and remember, but they accomplish this in vastly different ways from their older counterparts who have developed strategies that can be used to facilitate learning. These are important issues for the scientific community and educators alike since they relate to the ability of people to gain new knowledge and access it on demand. The research also showed that despite a growing body of knowledge, both Down's syndrome and Alzheimer's disease remain understudied, but there may be a genetic connection between these two conditions that warrants additional study.