How far back can we, as adults, remember details of our life experiences? Current popular and scientific beliefs are contradictory, with the latter stipulating that personal memories do not begin until the late preschool years (age 4–5 years) and the former claiming that we not only remember being born, but can also remember in utero experiences. In this review, these beliefs are examined in a scientific context and evaluated in terms of empirical data about the development of early memory. The theory proposed here is that memories for personal experiences are not possible until the advent of the cognitive self, around the age of 18 to 24 months. This age is much earlier than that proposed as the age of the earliest memories in other scientific accounts and much later than that proposed in popular beliefs about early memory. New data from a cross-sectional and longitudinal study of early memory development and the emergence of the self clearly show the origins of personal memory coincide with the emergence of the early self.
Following on from the target article, which presented a new model of procedural skill memory development, in this response I will reflect on issues raised by invited commentators and further expound attributes of the model. Discussion will focus on: evidence against sleep-dependent memory processing, definitions of memory stages and memory systems, and relationships between memory enhancement, sleep-stages, dreaming, circadian time, and sleep-disorders.
Modeling the cholinergic innervation in the infant cortico-hippocampal system and its contribution to early memory development and attention