Adults don’t have memories of their early ages. Why?

Note: This research is part of a series of assignments for Cognitive Psychology, part of my MSc in Psychology.

My first childhood memory comes from being separated from my brother at five in kindergarten. I found out that not having memories as an infant is called childhood amnesia/infantile amnesia, as the earliest memories in children appear at around three years  (Miles, 1895). Freud (1938) connected the lack of childhood memories to repression. Adults might have absent or very scarce memories before the age of four (Peterson et al., 2005), and Bauer et al. (2013) showed that children forget early memories starting at 3- to 4- years old, even if they initially showed cognition of the events.

Figure 1. Distribution of memories for infants up to 8 years of age

Schwarz et al. (1999), p. 130

Note: The distribution of memories according to various studies. The data shows the percentage of memories recalled before age 8, of a total of 8,610 memories (combined from all studies). Reprinted from Cognition, ageing, and self-reports (p. 130), by N. Schwarz et al., 1999, Psychology Press/Erlbaum (UK) Taylor & Francis. 

A potential explanation of childhood amnesia is that language acquisition plays an essential role in forming memories which explains the decline of memories from an early age. In addition, the parent-child recollection of past events also influences the development of autobiographical memory, the more elaborate the conversation style used by the parents, the better recollection of early childhood memories (Jack et al., 2010). 

Note: Childhood Amnesia starts around 8 and 9; we lose our episodic memories, but we keep other forms of memories (such as language or walking). One explanation is that the hippocampus produces many more neurons in infants, and those neurons shuffle with old ones to form new connections, which can erase memories. From SciShow. (2016, March 16). Why Can’t You Remember Being a Baby? [Video]. YouTube. Why Can’t You Remember Being a Baby? Accessed July 7, 2021. 

A more recent theory states that the hippocampus, cortex, and the functional connection between them are related to the formation and variations of the memory. Specific subfields of the hippocampus are developed late, until 5-7 years, which may explain the late maturity of memory (Riggins et al., 2020). One distinction to make for childhood amnesia is that children can form memories. Still, those memories are more susceptible to forgetting (Karen Tustin et al., 2016), correlated with high hippocampal neurogenesis in children, where new synaptic memories are likely to replace existing ones (Eysenck & Keane, p. 352, 2000). 

Note: The story of HM, the patient whose hippocampus was removed, who had severe long-term memory impairment; HM would not record memory long-term, so he lived the rest of his life not forming any memory after the age of the surgery. HM’s case brought new light on the essential role of the hippocampus in the formation of long-term memories. From Ted-ed. (2014, August 26).  What happens when you remove the hippocampus? Sean Ken. [Video]. YouTube. https://www.youtube.com/watch?v=KkaXNvzE4pk. Accessed July 7, 2021.

To this day, my childhood memories are composed of stories and old photos. It would be interesting to investigate potential ways to recover some of those memories and how certain individuals can remember being infants versus the rest of us, for whom life started at around 5-7 years of age.

References:

Anderson, J. R. (1984, January 1). The development of self-recognition: a review. Developmental Psychobiology. Wiley. https://doi.org/10.3758/BF03195836

Bauer, P. J., & Larkina, M. (2013, August 12). Childhood amnesia in the making: different distributions of autobiographical memories in children and adults. Journal of Experimental Psychology General. American Psychological Association. https://doi.org/10.1037/A0033307

Eysenck, M. W., & Keane, M. T. (2000). Cognitive psychology: A student’s handbook. Hove: Psychology Press.

Freud, S., & Brill, A. A. 1. (1938). The basic writings of Sigmund Freud. New York: The Modern Library.

Howe, M. L., & Courage, M. L. (1993, March 1). On resolving the enigma of infantile amnesia. Psychological Bulletin. American Psychological Association. https://doi.org/10.3758/BF03195836

Jack, F., & Hayne, H. (2010, October 4). Childhood amnesia: Empirical evidence for a two-stage phenomenon. Memory. Taylor & Francis Group (Informa). https://doi.org/10.1080/09658211.2010.510476

Miles, C. (1895, January 1). A Study of Individual Psychology. The American Journal of Psychology. University Of Illinois Press. https://doi.org/10.2307/1411191

Peterson, C., Grant, V. V., & Boland, L. D. (2005, August 1). Childhood amnesia in children and adolescents: their earliest memories. Memory. Taylor & Francis Group (Informa). https://doi.org/10.1080/09658210444000278

Riggins, T., Canada, K. L., & Botdorf, M. (2020, January 19). Empirical Evidence Supporting Neural Contributions to Episodic Memory Development in Early Childhood: Implications for Childhood Amnesia. Child Development Perspectives. Wiley. https://doi.org/10.1111/CDEP.12353

Schwarz, N., Park, D.C., Knaüper, B., & Sudman, S. (Eds.). (1999). Cognition, aging, and self-reports. Psychology Press/Erlbaum (UK) Taylor & Francis. https://doi.org/10.4324/9780203345115

Tustin, K., & Hayne, H. (2016, November 1). Early memories come in small packages: episodic memory in young children and adults. Developmental Psychobiology. Wiley. https://doi.org/10.1002/DEV.21423