Abstract
It is not exactly known why personal episodes from any time younger than about four years of age (infantile amnesia) can rarely be recalled. Recently, some studies suggested that explicit memory would develop later than implicit memory. However, few studies so far showed how implicit and explicit memory might develop. It is assumed that we could rarely recall childhood, because explicit memory has not well developed before four years of age. In order to investigate such phenomenon, I examined by longitudinal studies of recognition and episodic reports, whether the critical change would be observed around age four. The results revealed the following three tendencies. First, the age of the first recognition might be after age three. Second, the age of the first episodic reports could be earlier than at the first recognition. And third, the age of first episodic reports might depend on the first spoken words, while the age of the first recognition neither on the first words nor on the first episodic reports. New ideas on memory development in relation to language and consciousness have been suggested.
