Childhood amnesia

In psychology, childhood amnesia refers to the inability of people to remember their earliest childhood experiences. Childhood amnesia has been recognized for centuries, but the nature and cause of the phenomenon have been debated in psychology since the late 19th century. Sigmund Freud theorized that childhood amnesia occurs when a young mind blocks out unsuitable impressions or emotional trauma, which he considered a universal human experience. Few modern scientists who study human development consider that explanation plausible, and childhood amnesia remains somewhat of a paradox: infants' and young children's minds handle a lot of new impressions and are adept at learning, and yet it seems that long-term memories are only created after some fundamental developments of the brain are completed.

Characterisation
Childhood amnesia was first studied at the end of the 19th century by Freud, G. Stanley Hall and others. Since then it has been established that humans, regardless of age, cannot recall their earliest childhood. Many studies have been conducted to measure the cut-off age. Individually, peoples' earliest memories may be between two years to seven years of age, with the female mean earlier than that of males.

Defining and probing for the earliest memories is problematic. Often, subjects have heard stories about their childhood that mix with their real memories and make it difficult to differentiate what was actually remembered. Also, often a subject's earliest claimed memory is not confirmable; for this reason, memories like the birth of a younger sibling have been used in experiments when probing for the earliest possible memories.

There is a distinction between "sporadic memories" and "autobiographic memories", the latter being those that are part of the personal "narrative" of life. Also, an event that is often remembered may be rehearsed by the parents and those close to the child, so memories before or after that time may be remembered or forgotten.

Using methods that make it possible to probe infant memory (such as testing kicking in response to a mobile suspended over a crib that the infant previously learned moved when he/she kicked) Carolyn Rovee-Collier has shown that even young infants can remember an event over the entire “infantile amnesia” period if they are periodically exposed to appropriate nonverbal reminders. This work has challenged the notion that long-term memory does not develop until adulthood.

Mind development
Usually between the ages of two and three years, the brain of a child changes from tactile and olfactory processing of memories to verbal processing. Childhood amnesia is therefore theorised to be closely connected with the development of language and the creation of a self-image. This research has become increasingly of interest to those researching cognition and language learning.

Emotional memory
Our most vivid memories are associated with intense emotions, and the emotional changes associated with that experience. Since very early childhood is usually marked by a relatively limited emotional movement, and that the emotions occur at a relatively slow rate of change, some believe that this lack of emotional range is responsible for a lack of most childhood memories, with trauma being responsible for other childhood amnesia events.

Trauma
Many have questioned the veracity of psychoanalytic theories surrounding childhood amnesia, including Freud's theory centering on repressed memories of sexual abuse or other trauma. Freud theorized that such trauma would delay the cut-off for recalling, or cause memory gaps. Even though Freud's theory has not been confirmed, it has been reported that children subject to trauma during early childhood report fewer memories from their earliest years&sup1;

A neurocognitive hypothesis about childhood amnesia
Douglas Hofstadter states in an essay entitled Analogy as the Core of Cognition that infants before the ages of two or three do not form memories of the same type as we retrieve/reconstruct as older children and adults because most of their experiences cannot be comprehended and codified the way we "grasp" and make sense of our experiences. "...it has to do with the relentless, lifelong process of chunking-- taking 'small' concepts and putting them together into bigger and bigger ones, thus recursively building up a giant repertoire of concepts in the mind." The hypothesis is elaborated in Gentner D, Holyoak K, Kokanov B, eds. The Analogical Mind: Perspectives from Cognitive Science. Cambridge: MIT Press, 2000.