Visual short-term memory in the first year of life: capacity and recency effects.

A span task was developed to assess the amount of information infants could hold in short-term memory. In this task, infants were presented with up to 4 items in succession and then tested for recognition by successively pairing each item with a novel one. A large sample of full-terms and low-birth-weight preterms (< 1,750 g) was tested longitudinally, at 5, 7, and 12 months of age. Results were similar for both groups: (a) Longer spans were more difficult, especially at the 2 younger ages; (b) memory capacity increased over the 1st year of life--whereas less than 25% of the sample could hold as many as 3-4 items in mind at once at the younger ages, nearly half could do so by 12 months of age; (c) there was a marked recency effect (greater memory for the final item) for spans of 3 and 4 at all ages; and (d) there were modest cross-age correlations, indicating that individual differences in memory capacity showed some stability from age to age.