Long-term retention in 3.5-month-olds: familiarization time and individual differences in attentional style

Using a paired-comparison procedure, we examined the effect of familiarization variables on 3.5-month-old infants' (n = 120) retention of dynamic visual stimuli after 1-min, 1-day, and 1-month delays. The proportion of total looking time to the novel stimulus revealed novelty, null, and familiarity preferences after 1-min, 1-day, and 1-month delays, respectively, for infants who were permitted 30 s of familiarization time. Twenty seconds of familiarization time was insufficient to produce novelty preferences. These results support models of infant retention in which the direction of attentional preferences (novel, familiar, or null) depends on memory accessibility. To examine the impact of individual differences in familiarization or attentional style on memory, infants were identified as long or short lookers according to their peak-look duration on pretest and familiarization trial measures. Compared to long lookers, short lookers showed better retention over time indicating that much of the variability in the infant group data could be accounted for by these individual differences.