The ontogeny of long-term memory over the first year-and-a-half of life

TLDR

This research documents the development of long‑term memory in human infants from 2 months through the end of the first year‑and‑a‑half of life. The study trained 6‑ to 18‑month‑old infants in an operant task, testing retention after progressively longer delays until no retention for two consecutive weeks, and then combined these data with previously collected data from 2‑ to 6‑month‑olds in an equivalent task. Retention duration increased monotonically from 2 to 18 months, independent of age differences in initial learning, marking the first systematic analysis of long‑term memory across this developmental span and yielding a reference function for comparing retention across ages and tasks. © 1998 John Wiley & Sons, Inc., Dev Psychobiol 32: 69–89.

Abstract

This research documents the development of long-term memory in human infants from 2 months through the end of the first year-and-a-half of life. In the initial study phase, we trained 6- to 18-month-old human infants in an operant task and tested them after increasing delays until they exhibited no retention for 2 successive weeks. In the second phase, their data were combined with data previously obtained from 2- to 6-month-olds in an equivalent task. The resulting function revealed that the duration of retention increases monotonically between 2 and 18 months of age. This increase was not due to age differences in original learning. This is the first systematic analysis of the course of long-term memory across an extended period of infant development that is based on standardized parameters of training and testing. It provides a reference function against which measures of retention from infants of different ages that are obtained in different memory tasks with different parameters can be meaningfully compared. © 1998 John Wiley & Sons, Inc. Dev Psychobiol 32: 69–89, 1998