Amnesia, Infantile

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AMNESIA, INFANTILE

Do you remember being born? Your first birthday party? Your first day of school? Despite the significance of these early experiences, most adults recall little or nothing about them. The absence of autobiographical memory for events that occurred during infancy and early childhood is commonly referred to as infantile (or childhood) amnesia. Sigmund Freud originally identified the phenomenon of infantile amnesia by asking his patients to describe their earliest personal memories in the course of therapy. On the basis of these patient reports, Freud argued that the period of infantile amnesia extended into the sixth or eighth year of life. Freud's most often-cited explanation of infantile amnesia was highly influenced by his patient population. He believed that memories for our infancy and early childhood were stored in pristine condition, but were actively repressed due to their emotionally and sexually charged content. In fact, one goal of Freud's psychoanalytic process was to "unlock" these hidden memories to allow patients to come to terms with the traumatic thoughts and experiences of their childhood.

Subsequent normative studies of adults' earliest memories have shown that Freud probably overestimated the period of infantile amnesia. There is now general consensus that adults' earliest autobiographical memories are for events that occurred when they were approximately three to four years of age (Bruce, Dolan, and Phillips-Grant, 2000; Dudycha and Dudycha, 1941; Mullen, 1994; Sheingold and Tenney, 1982; Waldfogel, 1948) or even slightly younger (MacDonald, Uesiliana, and Hayne, 2000; Usher and Neisser, 1993). Furthermore, normative studies of adults' earliest memories have failed to provide any empirical evidence in support of Freud's repression model (Pillemer and White, 1989).

Thus, the fundamental question remains: Why is it that we have little or no recollection of events that occurred during our infancy and early childhood? Although repression does not provide an adequate explanation for the phenomenon, empirical studies point to a number of other factors that might account for infantile amnesia (Howe and Courage, 1993).

The Lower Boundary for Long-Term Recall of Early Experiences

Maturation of the Central Nervous System

Maturation of the human brain begins at conception, but continues throughout childhood (and beyond). Although our understanding of the time course of human brain development is not complete, we do know that many of the brain areas that play a role in long-term memory are not fully mature during infancy and early childhood. Thus, although learning occurs rapidly during this phase of development, the ability to retain and use information over a lifetime may be precluded by the immaturity of the brain (Campbell and Spear, 1972).

Maturation of two areas of the brain—in particular, the medial temporal lobe (including the hippocampus) and the frontal cortex—is thought to play a particularly important role in the phenomenon of infantile amnesia (Bachevalier, 1992). Maturation of the hippocampus occurs relatively early in development and may be sufficient to support some of the sophisticated memory skills exhibited by infants; however, maturation of the higher-association areas of the frontal cortex continues well into childhood and may be required for the maintenance and retrieval of memories over the long term (Hayne, Boniface, and Barr, 2000; C. Nelson, 1995).

The Development of Language

When we ask adults to recall their earliest personal memories, we commonly ask them to provide a verbal report of what they can remember—both the instructions they are given ("tell me about your earliest memory") and their response to those instructions require sophisticated language skills. Infants and children, on the other hand, typically express their memories, by necessity, through nonverbal behaviors. Even once they have acquired conversational language skills, children still rely primarily on their nonverbal skills to solve tasks that require memory. Furthermore, the ability to translate early, preverbal experiences into language is extremely limited, if not impossible (Simcock and Hayne, 2002). Although an early preverbal memory may be reflected in some aspect of an adult's behavior (Newcombe, Drummey, Fox, Lie, and Ottinger-Alberts, 2000), he or she will be unable to provide a verbal report of the original experience. In this way, language development is another rate-limiting step in the offset of infantile amnesia.

Beyond the Basic Ingredients: The Emergence of Autobiographical Memory

The basic ingredients for long-term verbal memory are in place by the end of the second year of life. For example, children as young as two and a half can provide a verbal report of an event that occurred eighteen months earlier (Fivush and Hammond, 1990). Despite this, most adults can recall nothing about events that occurred prior to their third or fourth birthday, and even those memories are few and far between and are significantly less vivid or detailed than events that occurred later in childhood. How can we account for this aspect of infantile amnesia?

A Framework for Organization

Many lines of research have shown that memory is enhanced when the to-be-remembered information can be organized according to some cognitive framework, or schema. Whether the material to be remembered consists of stories, baseball statistics, or lists of words, it is learned and retrieved most effectively by people who can systematically organize the material by relating it to an existing framework of knowledge. Without this kind of schematic organization, recall is only partial and fragmentary, if it occurs at all.

This same principle also applies to the recall of autobiographical information. When we think or talk about our past experiences, for example, we typically recall that information in chunks that reflect milestones in our lives: graduation from high school, attending college, getting married, the birth of our children and grandchildren, and so on. Our schema for these stages in our lives helps us to retrieve individual memories that occurred during each stage. Furthermore, thinking or talking about experiences from a particular stage often reminds us of other events that occurred during the same stage even if those events were greatly separated in time.

Children, on the other hand, do not organize their memories on the basis of milestones that reflect important stages of development or pivotal life events. Because these early experiences are not linked to the same schemata that adults use when they attempt to retrieve them, individual memories become difficult, if not impossible to recall (Pillemer and White, 1989).

Parent-Child Conversations about the Past

Children's emerging ability to organize and recount their life history is shaped through conversations about the past that occur in the context of their family (Fivush and Reese, 1992; Hudson, 1990; K. Nelson, 1993). In the course of reminiscing about mutually experienced events with parents or other significant social partners, children acquire the schema that are necessary to catalog their autobiographical memories. Additionally, conversations about the past allow children the opportunity to practice using another person's language to retrieve their own memory for a particular experience (e.g., "Remember when we went to the zoo last year?"). Furthermore, an adult's account of an event may augment the child's memory for the same experience, yielding a richer, more integrated (and thus more memorable) representation. The frequency and content of these conversations ultimately shape the number and clarity of our earliest recollections (MacDonald, Uesiliana, and Hayne, 2000; Mullen, 1994).

In conclusion, no single explanation of infantile amnesia can account for all of the available data. Instead, it is likely that brain maturation and language acquisition define the lower limit for our earliest recollections, but the number and quality of memories that actually survive will be determined by the way in which those memories have been structured and organized. Conversations about the past during early childhood are a driving force in this process.

Bibliography

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Bruce, D., Dolan, A., and Phillips-Grant, K. (2000). On the transition from childhood amnesia to the recall of personal memories. Psychological Science 11, 360-364.

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Dudycha, G. J., and Dudycha, M. M. (1941). Childhood memories: A review of the literature. Psychological Review 38, 668-682.

Fivush, R., and Hammond, N. R. (1990). Autobiographical memory across the preschool years: Towards reconceptualizing childhood amnesia. In R. Fivush and J. A. Hudson, eds., Knowing and remembering in young children, pp. 223-248. New York: Cambridge University Press.

Fivush, R., and Reese, E. (1992). The social construction of autobiographical memory. In M. A. Conway, D. C. Rubin, H. Spinnler, and W. A. Wagenaar, eds., Theoretical perspectives on autobiographical memory, pp. 115-132. Dordrecht: Kluwer Academic Publishers.

Freud, S. (1960). Three essays on the theory of sexuality: 2. Infantile sexuality. In The complete psychological writings of Sigmund Freud, vol. 7, pp. 173-206. London: Hogarth. The original definition of infantile amnesia. First published in 1905.

Hayne, H., Boniface, J., and Barr, R. (2000). The development of declarative memory in human infants: Age-related changes in deferred imitation. Behavioral Neuroscience 114, 77-83.

Howe, M., and Courage, M. (1993). On resolving the enigma of infantile amnesia. Psychological Bulletin 113, 305-326.

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Pillemer, D. B., and White, S. H. (1989). Childhood events recalled by children and adults. In H. W. Reese, ed., Advances in child development and behavior, Vol. 21, pp. 297-340. Orlando, FL: Academic Press.

Sheingold, K., and Tenney, Y. J. (1982). Memory for a salient childhood event. In U. Neisser, ed., Memory observed, pp. 201-212. San Francisco: Freeman.

Simcock, G., and Hayne, H. (2002). Breaking the barrier? Children fail to translate their preverbal memories into language. Psychological Science 13, 225-231.

Usher, J. A., and Neisser, U. (1993). Childhood amnesia and the beginnings of memory for four early life events. Journal of Experimental Psychology: General 122, 155-165.

Waldfogel, S. (1948). The frequency and affective character of childhood memories. Psychological Monographs 62, 1-39.

UlricNeisser

Revised byHarleneHayne

Learning and Memory