The shifting boundary of childhood amnesia

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Sigmund Freud called it 'the remarkable amnesia of childhood'¹. When you ask people to recall their earliest experiences, they rarely report memories dating from much before about three years of age. Since Freud made his observations, the phenomenon of childhood amnesia has been the subject of much research and theorizing, with many different explanations put forward to explain this intriguing phenomenon. One possibility is that early experiences are not properly encoded, which means that they cannot be stored for later retrieval. The problem with this explanation is that we know from other research (and casual observation) that memory processes are functional in infancy and early childhood. The issue is not with children remembering things, but with them continuing to do so when they reach adulthood.

Why do adults suffer from this forgetfulness? One response might be that it's not adults that we should be asking. Some recent studies have shown that, if you ask the question in childhood, you get an earlier point of 'offset' of childhood amnesia—that is, the respondents' earliest memories seem to go back further. To test this idea out some more, Karen Tustin and Harlene Hayne at the University of Otago have taken a new approach to the subject. In their study, published in the last issue of Developmental Psychology², they recruited four groups of participants: young children (age 5), older children (age 8-9), adolescents (age 12-13), and adults (age 18-20). There were twelve people in each group, with equal numbers of males and females. For each participant, the researchers created what they call a Timeline: a horizontal line depicting different years of the individual's life, with photos of the participant attached at some of the ages.

Once the participants had shown that they understood what the Timeline signified, they were asked about their memories of first a recent and then some more distant events—specifically, an event from age 3, one from before age 3, and the earliest memory that could be brought to mind. Dating the event was a matter of indicating on the Timeline where the memory fitted in; these reports were also confirmed where possible by parents. Participants were additionally asked about events from those times which their parents had nominated as being particularly significant.

The findings support the idea of a shifting boundary of childhood amnesia. The children (both younger and older groups) reported a greater proportion of pre-three memories than did the adults. More than 20% of the memories of the children dated from before the first birthday. Most of the children's memories were pre-three; most of the adolescents' and adults' were post-three.

When the researchers looked at the very earliest memories reported, they found that the average age of the earliest memory was younger for the children: between one and two years, compared with about three-and-a-half for the adults. The memories of children, adolescents, and adults were equally episodic in quality, suggesting that children were genuinely recalling events and not simply parroting stories they had heard about their lives. The conclusion is obvious: children are not as amnesic about their early lives as adults are.

Among other things, these findings challenge the view that episodic memory cannot get going until the preschool years. If you ask young children about their pasts, they will report episodic memories. My study of Athena's development up to the age of three showed me that she remembered plenty of things that had happened to her, and could gladly talk to me about details of her short life to now. Something else must be stopping these early episodic memories from making it through into adulthood.

The key to explaining this amnesia may lie in the changing organization of these memories. I have blogged elsewhere on how disorganized memory information may get lost over the first few years. There remains much more for us to find out about these processes, including obtaining greater clarify on the role of other cognitive processes in remembering, and specifying the involvement of the developing neural systems that underlie episodic memory. For now, the moral is clear: if you want to know about a person's past life, catch them early.

¹ Freud, S. (1905/1963). The Standard Edition of the complete psychological works of Sigmund Freud, Vol. 15 (translated and edited by James Strachey). London: Penguin.

² Tustin, K., & Hayne, H. (2010). Defining the boundary: Age-related changes in childhood amnesia. Developmental Psychology, 46, 1049-1061.