The functional locus of intrusions: encoding or retrieval?

Many current accounts of the origin of intrusions and other confabulatory-like phenomena emphasize the role of a retrieval or postretrieval deficit in these disorders. In the experiments reported herein we examine whether the presence of an interfering task at encoding elicits more intrusions in normal subjects than the presence of an interfering task at retrieval. In Experiment 1, performance in story recall without interference was compared to the performance with an interfering task at retrieval. In Experiment 2, the performance in story recall with an interfering task at encoding was compared to performance in story recall with interference at encoding and retrieval. Results suggest that interference at retrieval has no effect on the accuracy of recall and on intrusions. Interference at encoding compared to interference at encoding and retrieval (Experiment 2) had no effect on the accuracy of recall and on frequency of intrusions. Cross-experiment comparisons suggest that interference at encoding affects both the accuracy of retrieval and the probability of intrusions in recall. These results suggest that encoding processes, more than retrieval processes, have a role in eliciting intrusions.