Research into memory processes has progressed in recent years through the combined efforts of neuroscientists and cognitive scientists, aided by positron emission tomography and functional magnetic resonance imaging (Schacter, 1997). Most of the research advances in memory that help scien- tists understand learning come from two major groups of studies: studies that show that memory is not a unitary construct and studies that relate features of learning to later effectiveness in recall.
Memory is neither a single entity nor a phenomenon that occurs in a single area of the brain. There are two basic memory processes: declarative memory, or memory for facts and events which occurs primarily in brain systems involving the hippocampus; and procedural or nondeclarative memory, which is memory for skills and other cognitive operations, or memory that cannot be represented in declarative sentences, which occurs princi- pally in the brain systems involving the neostriatum (Squire, 1997).
Different features of learning contribute to the durability or fragility of memory. For example, comparisons of people’s memories for words with their memories for pictures of the same objects show a superiority effect for pictures. The superiority effect of pictures is also true if words and pictures are combined during learning (Roediger, 1997). Obviously, this finding has direct relevance for improving the long-term learning of certain kinds of information.
Research has also indicated that the mind is not just a passive recorder of events, rather, it is actively at work both in storing and in recalling infor- mation. There is research demonstrating that when a series of events are presented in a random sequence, people reorder them into sequences that make sense when they try to recall them (Lichtenstein and Brewer, 1980). The phenomenon of the active brain is dramatically illustrated further by the fact that the mind can “remember” things that actually did not happen. In one example (Roediger, 1997), people are first given lists of words: sour- candy-sugar-bitter-good-taste-tooth-knife-honey-photo-chocolate-heart-cake- tart-pie. During the later recognition phase, subjects are asked to respond “yes” or “no” to questions of whether a particular word was on the list. With high frequency and high reliability, subjects report that the word “sweet” was on the list. That is, they “remember” something that is not correct. The finding illustrates the active mind at work using inferencing processes to relate events. People “remember” words that are implied but not stated with the same probability as learned words. In an act of efficiency and “cognitive economy” (Gibson, 1969), the mind creates categories for processing infor- mation. Thus, it is a feature of learning that memory processes make rela- tional links to other information.
cific experiences have specific effects on the brain, the nature of “experi- ence” becomes an interesting question in relation to memory processes. For example, when children are asked if a false event has ever occurred (as verified by their parents), they will correctly say that it never happened to them (Ceci, 1997). However, after repeated discussions around the same false events spread over time, the children begin to identify these false events as true occurrences. After about 12 weeks of such discussions, children give fully elaborated accounts of these fictitious events, involving parents, sib- lings, and a whole host of supporting “evidence.” Repeating lists of words with adults similarly reveals that recalling non-experienced events activates the same regions of the brain as events or words that were directly experi- enced (Schacter, 1997). Magnetic resonance imaging also shows that the same brain areas are activated during questions and answers about both true and false events. This may explain why false memories can seem so com- pelling to the individual reporting the events.
In sum, classes of words, pictures, and other categories of information that involve complex cognitive processing on a repeated basis activate the brain. Activation sets into motion the events that are encoded as part of long-term memory. Memory processes treat both true and false memory events similarly and, as shown by imaging technologies, activate the same brain regions, regardless of the validity of what is being remembered. Expe- rience is important for the development of brain structures, and what is registered in the brain as memories of experiences can include one’s own mental activities.
These points about memory are important for understanding learning and can explain a good deal about why experiences are remembered well or poorly. Particularly important is the finding that the mind imposes struc- ture on the information available from experience. This parallels descrip- tions of the organization of information in skilled performance discussed in Chapter 3: one of the primary differences between the novice and the expert is the manner in which information is organized and utilized. From the perspective of teaching, it again suggests the importance of an appropri- ate overall framework within which learning occurs most efficiently and effectively (see evidence discussed in Chapters 3 and 4).
Overall, neuroscience research confirms the important role that experi- ence plays in building the structure of the mind by modifying the structures of the brain: development is not solely the unfolding of preprogrammed patterns. Moreover, there is a convergence of many kinds of research on some of the rules that govern learning. One of the simplest rules is that practice increases learning; in the brain, there is a similar relationship be- tween the amount of experience in a complex environment and the amount of structural change.
final answers, to questions of great interest to educators. There is growing evidence that both the developing and the mature brain are structurally altered when learning occurs. Thus, these structural changes are believed to encode the learning in the brain. Studies have found alterations in the weight and thickness of the cerebral cortex of rats that had direct contact with a stimulating physical environment and an interactive social group. Subse- quent work has revealed underlying changes in the structure of nerve cells and of the tissues that support their function. The nerve cells have a greater number of the synapses through which they communicate with each other. The structure of the nerve cells themselves is correspondingly altered. Un- der at least some conditions, both astrocytes that provide support to the neurons and the capillaries that supply blood may also be altered. The learning of specific tasks appears to alter the specific regions of the brain involved in the task. These findings suggest that the brain is a dynamic organ, shaped to a great extent by experience—by what a living being does, and has done.
CONCLUSION
It is often popularly argued that advances in the understanding of brain development and mechanisms of learning have substantial implications for education and the learning sciences. In addition, certain brain scientists have offered advice, often with a tenuous scientific basis, that has been incorporated into publications designed for educators (see, e.g., Sylwester, 1995:Ch. 7). Neuroscience has advanced to the point where it is time to think critically about the form in which research information is made avail- able to educators so that it is interpreted appropriately for practice—identi- fying which research findings are ready for implementation and which are not.
This chapter reviews the evidence for the effects of experience on brain development, the adaptability of the brain for alternative pathways to learn- ing, and the impact of experience on memory. Several findings about the brain and the mind are clear and lead to the next research topics:
1. The functional organization of the brain and the mind depends on and benefits positively from experience.
2. Development is not merely a biologically driven unfolding process, but also an active process that derives essential information from experi- ence.
3. Research has shown that some experiences have the most powerful effects during specific sensitive periods, while others can affect the brain over a much longer time span.
tion is which things are tied to critical periods (e.g., some aspects of phone- mic perception and language learning) and for which things is the time of exposure less critical.
From these findings, it is clear that there are qualitative differences among kinds of learning opportunities. In addition, the brain “creates” informa- tional experiences through mental activities such as inferencing, category formation, and so forth. These are types of learning opportunities that can be facilitated. By contrast, it is a bridge too far, to paraphrase John Bruer (1997), to suggest that specific activities lead to neural branching (Cardellichio and Field, 1997), as some interpreters of neuroscience have implied.