Childhood amnesia

Childhood amnesia, also known as infantile amnesia, is the common inability of adults to remember the earliest years of their childhood. The amnesia generally covers events from birth until around four years old.

Characterization and background

Infantile, or childhood amnesia is characterized by the relative absence of memory before 3 or 4 years of age. It is important to note that the term does not refer to complete absence of memories, but the relative scarcity of memories during infancy — a scarcity that cannot be accounted for by a forgetting curve.^{[citation needed]} Additionally, the boundary is malleable and can be influenced by both individual experiences^[1] and cultural factors.^[2]

Research has demonstrated that children are adept learners and are quick to acquire and retain information. Children do remember events; however, these memories accessible as children are lost to infantile amnesia in adulthood.^[3][4]

Research on childhood amnesia generally uses easily-verifiable, highly salient events such as the birth of a sibling to test recall to avoid difficulties with unreliability of reporting and memories of children in general.^[1]

Early observations

Childhood amnesia, despite being a universal human experience, was only first formally studied in 1893 by the psychologist Caroline Miles in her 1893 article "A study of individual psychology" published in the American Journal of Psychology.^[5] In 1904 G. Stanley Hall noted the phenomenon in his book Adolescence.^[6] but it was Sigmund Freud who offered one of the first, most famous, and most controversial descriptions and explanations of childhood amnesia when he tied the phenomenon in with psychoanalysis.^[5]

Modern observations

It has been suggested that the average age of the first memories is three years, six months, with the vast majority of subjects dating their first recollection somewhere between ages 2 and 5 years.^[7][8] Early (i.e. childhood) and late (i.e. adult) memories show few differences in emotional versus factual, and episodic versus non-episodic content of the memories.^[3] Very few memories of adults precede 30 months, and those that are reported at this time show considerable confabulation with individuals unable to tell the difference between a memory of an event and simple knowledge of the event (i.e. gained from discussion by others).^[9]

Proposed explanations

Since Miles first officially documented childhood amnesia as a psychological phenomenon, many theories of its causes and character have been developed and none have proven significantly more useful or true than any others.

Freud’s trauma explanation

Sigmund Freud’s theories of psychosexual development are highly intertwined with childhood experiences, and Freud’s explanation of childhood amnesia is one of the most controversial. In what is now published as The Standard Edition of the Complete Psychological Works of Sigmund Freud, Freud theorized that childhood amnesia is the result of the mind’s attempt to repress memories of traumatic events that, according to Freud, necessarily occur in the psychosexual development of every child. This would lead to the repression of the majority of the memories of the first years of life. Freudian theory, including his explanation for childhood amnesia, has been criticized for extensive use of anecdotal evidence rather than scientific research, and said to frequently permit multiple interpretations.^[10]

Physical development explanation

Childhood amnesia may also be due to the lack of neurological development of the infant brain, preventing the creation of long term or autobiographical memories. Two key structures in the neuroanatomy of memory, the hippocampus and prefrontal cortex, do not develop into mature structures until the age of three or four years. These structures are known to be associated with the formation of autobiographical memories of the type notably missing from adult recollection of early childhood.^[10][11]

Language explanation

The incomplete development of language in young children may be a cause of childhood amnesia in that infants do not have the language capacity to encode autobiographical memories in a manner that their language-based adult selves can interpret correctly. The typical schedule of language development seems to support this theory. Babies of one year old tend to be limited to one word utterances, and childhood amnesia predicts that adults have very few, if any, memories of this time. By the age of three, children are capable of two or three word phrases, and by age five their speech already resembles adult speech. This language development seems to very much correspond to childhood amnesia because it is around the age of three to four that is the time of most adults’ earliest recallable memory.^[10] Pre-verbal children shown a picture of a memorable event from a year previously demonstrate verbal and nonverbal recall, but describe the experience solely using language skills available at the time the memory was created.^[12]

Emotion explanation

The amygdala-governed memory pathway (which is primarily concerned with emotions and emotional content of memories) and hippocampus-governed pathway (which concerns primarily autobiographical memories) are generally independent, but emotions and the amygdala are known to play a role in the encoding of memories typically associated with the hippocampus.^[13] It has been suggested that the differences between the emotions experienced by infants and adults may be a cause of childhood amnesia.^[3] The idea that highly emotional events can stimulate and improve recall (the "flashbulb memory") is still being debated and belief in these types of memories is the primary proof of the effects of emotion on memory.^[14]

Context explanation

The difference in perspective that children and adults experience of the world may be a cause of childhood amnesia. For children, their physical perception of objects and their understanding of people and events are very different from the world of the adult. Moreover, an infant’s basic understanding of the universe, like object permanence or occlusion effects, is not innate at birth. This leads to a disparity in retrieval cues used by the adult and those used by the infant, who will encode memories without many of these principles that are ingrained in the mind of the adult trying to recollect. This different context could lead to the inability of the adult to remember his earliest years at all.^[10] An infant's development of a theory of mind is linked to the ability to form an episodic memory, and the development of the ability to contextualize memories at the age of 3 to 5 may be the source of people's first retrievable memories.^[15] The development of self-awareness at around two years of age has also been proposed as an explanation, where memories are inherently associated with one's sense of self, such that memories encoded before self-awareness develops are not comprehensible to the individual even though some information is stored in the brain.^[16]

Patterns of childhood amnesia

Much recent research has found patterns in the extent of childhood amnesia. The most prominent patterns are gender and race.

Males versus females

In general the earliest recollections of females are earlier and more vivid than those of males.^[10][17][18] It has been suggested that this pattern is due to differences in how males and females interact as children, especially the types of conversations they have.^[10]

Race and ethnicity

Race has also been shown to play a role in the effect of childhood amnesia. One study found that Europeans had later first retrievable memories than Maori, and Asians had still later ones. This suggests that the importance of the past in Maori culture may have something to do with their particularly early first retrievable memory.^[18]

See also

• Developmental psychology

References