Infantile Amnesia

Infantile amnesia, also called childhood amnesia, is the inability of adults to retrieve episodic memories of specific situations or events from before roughly age three to four, with the period of fragmented, sparse memory typically ending by around four years and eight months of age. The psychologist Caroline Miles first formally reported the phenomenon in 1895 in the American Journal of Psychology, and researchers Henri and Henri found in 1900 that people's average earliest recollection dated to around three years and one month of age; the developmental psychologist G. Stanley Hall documented the phenomenon further in his 1904 book Adolescence. Sigmund Freud offered the most famous early explanation in 1910, proposing that early memories were actively repressed because of their sexual content during psychosexual development, though no experimental research has ever found evidence supporting this idea. More recent explanations instead point to biological and cognitive development: the hippocampus and prefrontal cortex, both critical to forming autobiographical memories, are not fully mature until around age three or four; the language capacity needed to encode memories in a lasting, narratively organized way may not be sufficiently developed before that age either; a very high rate of new neuron growth in the infant hippocampus may itself degrade already-stored memories through competition for the same neural connections; and a stable, continuous sense of personal identity, which does not fully emerge until around age four or five, may be a necessary organizing framework for autobiographical memory to take hold.