Are first impressions lasting impressions? An exploration of the generality of the primacy effect in memory for repetitions.

In five experiments, we investigated the primacy effect in memory for repetitions (DiGirolamo & Hintzman, 1997), the finding that when participants are shown a study list that contains two very similar versions of the same stimulus, memory is biased in the direction of the version that was presented first. In the experiments reported, the generality of the effect was examined by manipulating the orientation and features of the repeated stimuli. The results confirmed that the effect is reliable when stimulus changes affect the accidental properties of the stimulus (properties of the stimulus that give information about distance or angle but do little to aid in identification). However, the effect was not found when changes were made to other aspects of the stimulus. The results suggest that the primacy effect in memory for repetitions is not robust across all stimulus changes and converge with previous findings that have demonstrated that such properties of stimuli as orientation and size are represented differently in memory than are other stimulus characteristics.