Retrieval-induced forgetting in an eyewitness-memory paradigm.

The potential impact of repeated questioning of a witness was examined. Subjects were shown slides depicting the aftermath of a theft and subsequently were asked several times to recall selected details of what they saw. Previous experiments employing simple verbal materials have demonstrated that information addressed by questioning becomes more recallable in the future than it would have been without such retrieval practice, but other information, especially that bearing a categorical similarity to the practiced items, becomes less recallable. Such positive and negative effects appeared in subjects' later recall of crime-scene details in the present experiment. These results have an important implication for legal practice: Repeated interrogation of a witness can modify the witness's memory-enhancing the recall of certain details while inducing the forgetting of other details-even when no misinformation is contained or implied in the questioning.