Serial lists contain information about item identity and item order. Using a task designed for nonverbal animals, we previously found that 3- and 6-month-olds exhibited a primacy effect after 24 hr, remembering both item identity and item order. Presently, we examined their memory of list information after longer delays. In Experiment 1, the serial-position curve reverted to a U-shape after 1 week at both ages, revealing that the common practice of attributing primacy and recency effects to long- and short-term memory, respectively, is flawed. In Experiment 2, a precuing procedure confirmed that 6-month-olds' memory still contained order information after 1 week, but 3-month-olds' reactivated memory contained none. Experiments 3A and 3B confirmed that increasing the complexity of information that was learned shortened the delay after which it could be retrieved. Testing infants after delays longer than have previously been used with animals or human adults sheds new light on an old phenomenon.
Copyright 2001 John Wiley & Sons, Inc.