Children, Development of Memory in
CHILDREN, DEVELOPMENT OF MEMORY IN
Memory improves dramatically as children develop. The first section of this entry describes the factors that contribute to improved memory during childhood and adolescence. With this general developmental profile as a backdrop, several special topics in children's memory are discussed in the remainder of the entry.
How Memory Develops During Childhood and Adolescence
Two factors play a critical role in the development of memory during childhood and adolescence: greater use of strategies and greater task-relevant knowledge.
Developmental Change in Use of Memory Strategies
A strategy is any deliberate act that is designed to improve retention. One common strategy is rehearsal, in which people spontaneously repeat (either aloud or silently) information to be remembered. As children grow they are more likely to use strategies to help them remember. Rehearsal, for example, typically emerges at about six or seven years of age. In addition, as children and adolescents develop, they tend to abandon simple but relatively ineffective strategies in favor of complicated but more effective strategies. In the case of rehearsal, school-age children often simply repeat the information exactly as it was presented. In contrast, older children and adolescents are more likely to modify their rehearsal as necessary to fit the nature of the material. Instead of repeating words in the order presented, older children and adolescents may reorganize the words, rehearsing together words that are related semantically.
The general trend for children to use strategies more often and more effectively as they grow apparently reflects parallel developmental changes in children's ability to diagnose memory tasks and to monitor the effectiveness of their chosen strategy. That is, young children often underestimate the difficulty of memory problems, and consequently may underestimate the need for a strategy to remember effectively. Also, young children are less likely than older children to realize that a strategy is not working and should be abandoned for a better strategy (Kail, 1990).
Knowledge and Memory
As children develop, they acquire more and more knowledge of their worlds. Such understanding is an important aid to memory. To explain the impact of knowledge on memory, psychologists represent a person's knowledge as a network like the one shown in Figure 1. This network consists of nodes (the ellipses) linked by different types of associations: isa links denote category membership; can and has denote properties of the node.
Knowledge like that depicted in Figure 1 can aid memory because it provides special codes that simplify memorization. To illustrate, suppose that people were asked to remember a list of words like collie, terrier, Dalmatian, poodle. In this case, the category name dogs serves as a code for the list. People can recall the category name, then scan memory for words associated with that name and decide if they were presented. Thus, one benefit of children's growing knowledge is that they are more likely to be able to provide a code that reduces the amount of material that must be remembered.
Another way that children's growing knowledge benefits memory is by providing more retrieval cues. Each of the links in Figure 1 provides an alternative way, a cue, to gain access to a word that was presented. Thus, the more links the better. When people are expert in some domain, their knowledge will be linked extensively. If they know little, their knowledge will have relatively few links. Consequently, older children and adolescents will typically have more cues available to recall information than will younger children.
Knowledge is not always beneficial, because it can distort memories. Information to be remembered is often changed so that it conforms to one's existing knowledge or stereotypes. To illustrate, when children hear stories in which superheroes are said to be weak or ugly, they tend to recall the heroes as strong and attractive. Similarly, if asked to remember the actions of boys and girls whose behaviors violate sex-role stereotypes (e.g., a girl sawing wood), children will change the sex of the actor to make it consistent with sex-role knowledge.
The remainder of this entry considers three special topics: origins of memory, children's eyewitness testimony, and working memory.
Origins and Early Development of Memory
Most methods used to study memory in children and adolescents cannot be used with infants because they require speaking or writing. Consequently, the study of infants' memory became possible only after psychologists devised techniques that took advantage of infants' abilities to respond in other ways. One approach is to show a stimulus to an infant; immediately thereafter, the infant is shown the same stimulus with a novel stimulus. Infants typically look longer at the novel stimulus, behavior possible only if they remember the one stimulus from its original presentation. Newborns tested on novelty-preference tasks look longer at novel stimuli, indicating that some form of memory is functional at birth.
In another method used to assess infants' memory, a mobile is placed over an infant's crib and a ribbon connects the infant's leg to the mobile. Infants kick vigorously just a few minutes after their leg is connected to the mobile, demonstrating that they have learned the relation between their kicking and the mobile's movement. To study infant memory, time is allowed to pass, then the infant's leg is reconnected to the mobile. If the infant immediately begins to kick vigorously, then the infant apparently has remembered the relation between his or her kicking and the mobile's movement. If, instead, kicking gradually becomes more vigorous—as if the infant is relearning the relation—then the infant has forgotten the relation.
Research based on techniques like these has demonstrated that by the age of three months infants will remember the link between kicking and the moving mobile for up to fourteen days. That is, when an infant's leg is reconnected to the mobile within fourteen days of the original learning, the infant will kick vigorously, without the need to relearn the relation. When a sufficiently long interval had elapsed such that infants no longer kick (i.e., they apparently have forgotten that kicking moves the mobile), a cue helps infant to remember. If the experimenter moves the mobile for the infant, who is later connected to the mobile with the ribbon, the infant will again kick, apparently signifying that the infant remembers the link between kicking and the moving mobiles. Thus, experiments show that three important features of memory exist as early as two and three months of age: an event from the past is remembered; over time, the event can no longer be recalled; and a cue can serve to dredge up a memory that seems to have been forgotten (Rovee-Collier, 1999).
Both of these memory tasks demonstrate that infants are able to recognize events experienced previously. Other methods are used to assess recall, which refers to retrieving from memory a representation of a past experience that is not currently perceptible (e.g., remembering what one had for dinner yesterday). With older children and adults, recall is usually assessed by having people describe verbally what happened in the past. This method is not appropriate for infants and toddlers with limited language; instead, researchers have relied upon imitation tasks. An experimenter demonstrates novel actions with simple toys; the toys are then presented to children—either immediately or after a delay—and children are encouraged to play with the toys. Accurate imitation of the actions is taken as evidence of recall memory, particularly when children reproduce multiple actions in the correct order.
Research with this method has revealed several important features of early recall memory. First, recall emerges at about nine months: At this age infants can imitate novel events after seeing them modeled once. Second, the amount of information that children can recall immediately—defined as the number of actions from the sequence that are reproduced accurately—increases steadily from two actions at eleven months of age to eight actions at thirty months of age. Third, with development, children can recall events over increasingly large intervals, from four weeks at thirteen months of age to one year at twenty months of age. Fourth, infants and toddlers recall more accurately when they experience events more than once and when they actively participate in the events (e.g., imitate the actions once before the delay).
Children's Eyewitness Testimony
Memory for past events is particularly important when children are asked to provide eyewitness testimony, as they sometimes are in cases of child abuse (Bruck and Ceci, 1999). Although children, even three-to five-year-olds, can remember past events accurately, many commonly used legal procedures can lead children to confuse what actually happened with what others suggest may have happened. This is especially true when interviewers are biased—that is, when interviewers believe they know what happened and use questioning to attempt to confirm these beliefs. The typical result is a highly suggestive interviewing technique that is unlikely to help children recall events accurately. For example, interviewers often ask misleading questions (e.g., ones that imply events happened when they may not have happened) or ask the same question repeatedly (implying that the child's previous answers were wrong); both procedures increase the chances that a child will describe events that never happened.
One particularly controversial practice is the use of anatomically correct dolls to aid children's recall. Many professionals are strong advocates of these dolls, claiming that they improve memory by overcoming children's embarrassment over talking about private events or by overcoming their ignorance of the names of body parts. In fact, research indicates that the use of anatomically correct dolls increases the number of false reports, apparently because the examiner's description of the dolls implicitly encourages children to create stories about body parts.
To improve the reliability of children's testimony, they should not be questioned repeatedly on a single issue and they should be warned that interviewers may sometimes try to trick them (e.g., suggest things that didn't happen). In addition, interviewers should be neutral in their questioning and evaluate alternative explanations of a particular event and who was involved.
Working memory denotes a cognitive structure that includes ongoing information processing as well as the data required for those processes. According to one widely accepted view (Baddeley, 1992), working memory includes a central executive as well as two separate subsystems for storing verbal and spatial information. To measure working memory, investigators often ask people to remember information while concurrently performing other processing tasks. Participants may be asked to read sets of sentences and concurrently remember the last word from each sentence in the set. Testing begins with one or two sentences (hence, participants must remember one or two sentence-ending words) and continues until participants are no longer able to recall the sentence-ending words in the correct sequence. Assessed in this manner, working memory increases substantially during childhood and adolescence.
Researchers have identified the causes and consequences of age-related change in working memory. Regarding the causes, age-related changes in working memory are due primarily to age-related increases in the speed with which children can execute basic cognitive processes. As children develop, their processing speed increases, which allows them to execute the various updating functions of working memory more rapidly. For example, more rapid processing speed results in more rapid rehearsal and more rapid retrieval of items in working memory.
Regarding the consequences, age-related change in working memory contributes to improved reasoning and problem solving during infancy, childhood, and adolescence. That is, in the course of reasoning and solving problems, individuals must remember task elements and coordinate task-relevant operations, which are functions attributable to working memory. Consequently, as the capacity of working memory increases with age, children have more resources available to storing and processing operations during reasoning and problem solving, resulting in improved performance (Kail, 2002). Thus, as children develop, they process information more rapidly, which allows them to use working memory more effectively. This, in turn, produces improved reasoning and problem solving.
Memory improves during childhood and adolescence, due to age-related increases in use of memory strategies and age-related increases in knowledge. Recognition and recall are both evident in the first year of life. Young children can recall past events accurately during legal proceedings, but biased interviewers may alter children's testimony. Working memory increases with age and contributes to age-related improvement in reasoning and problem solving.
Baddeley, A. (1992). Working memory. Science 255, 556-559.
Bruck, M. B., and Ceci, S. J. (1999). The suggestibility of children's memory. Annual Review of Psychology 50, 419-439.
Kail, R. (1990). The development of memory in children, 3rd edition. New York: W. H. Freeman.
—— (2002). Information processing and memory. In M. Bornstein, L. Davidson, C. L. M. Keyes, K. A. Moore, and The Center for Child Well-Being, eds., Well-being: Positive development across the life course. Mahwah, NJ: Erlbaum.
Rovee-Collier, C. (1999). The development of infant memory. Current Directions in Psychological Science 8, 80-85.
Revised byRobert V.Kail