Timing effects of postevent information on infant memory

The role of the timing of postevent information on retention was assessed with 124 6-month-olds. In four experiments, infants learned to kick to move a particular crib mobile (the original target), were passively exposed to a discriminably different mobile (the postevent information), and were tested for recognition of the original mobile, the postevent-exposure mobile, or a completely novel mobile 24 h later. All interpolated exposures occurred after delays when infants' retention of the training mobile is excellent. In Experiment 1, the interpolated information precluded recognition of the training mobile (memory impairment) after all exposure delays. In Experiment 2, when the interpolated information was exposed within a week of training, infants treated the exposure mobile as if they had actually been trained with it (memory facilitation). Despite the recognition failures in Experiments 1-2, both original and exposure mobiles later reactivated the training memory, but only if the interpolated exposure was early in the retention interval; if it was later, only the exposure mobile was an effective reminder (Experiments 3A-3B). In Experiment 4, exposing postevent information after longer delays led infants to respond to a completely novel mobile (categorization). These findings demonstrate that postevent information has different qualitative effects depending on its timing and provides a basis for understanding discrepant reports of postevent-information effects with children and adults. (C) 1996 Academic Press, Inc.