Effects of postevent information on infants' memory for a central target.

In three experiments with 78 infants, we explored the effect of introducing novel information about a central target after a short delay on 6-month-olds' recognition of the original target, the novel exposure target, and a completely novel one. In all experiments, infants learned to move a particular crib mobile (the central target) by kicking and then were exposed to a novel mobile (the conflicting postevent information) immediately after training was over. In Experiment 1, memory for the original mobile was unimpaired, but infants treated both the exposure mobile and a completely novel one as if they had actually been present originally. In Experiment 2, only a completely novel mobile was an effective remainder in a reactivation paradigm, indicating that the impact of postevent information was relatively long-lasting and that the failure of the other mobiles to recover the training memory resulted from trace competition at the time of retrieval. In Experiment 3, identical novel information did not proactively affect recognition. Thus, 6-month-olds' memory of a central target is resistant to impairment by conflicting postevent information after a short delay, but they are highly prone to source misattribution. We propose that postevent information effects are cognitively efficient.