Certain reliable findings from research on directed forgetting seem difficult to accommodate in terms of the theoretical processes, such as selective rehearsal or storage differentiation, that have been put forward to account for directed-forx getting phenomena. Some kind of "missing mechanism" appears to be involved.In order to circumvent the methodological constraints that have limited the conclusions investigators could draw from past experiments, a new paradigm is introduced herein that includes a mixture of intentional and incidental learning. With this paradigm, a midlist instruction to forget the first half of a list was found to reduce later recall of the items learned incidentally as well as those learned intentionally. This result suggests that a cue to forget can lead to a disruption of retrieval processes as well as to the alteration of encoding processes postulated in prior theories. The results also provide a link between intentional forgetting and the literature on posthypnotic amnesia, in which disrupted retrieval has been implicated. With each of these procedures, the information that can be remembered is typically recalled out of order and often with limited recollection for when the information had been presented. It therefore was concluded here that retrieval inhibition plays a significant role in nonhypnotic as well as in hypnotic instances of directed forgetting. The usefulness of retrieval inhibition as a mechanism for memory updating was also discussed.

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This research compared the effectiveness of three interview procedures for optimizing eyewitness memory performance: (a) the "cognitive interview" based on memory-retrieval mnemonics from current memory theory, (b) the presently controversial hypnosis interview, and (c) the standard (control) police interview. These methods were evaluated empirically in a controlled, yet ecologically valid, laboratory setting. Eighty-nine subjects viewed police training films of simulated violent crimes and were questioned individually in interactive interviews 48 hours later by experienced law-enforcement personnel. Both the cognitive and hypnosis procedures elicited a significantly greater number of correct items of information from the subjects than did the standard interview. This result, which held even for the most critical facts from the films, was most pronounced for crime scenarios in which the density of events was high. The number of incorrect items of information generated did not differ across the three interview conditions. The observed memory enhancement was interpreted in terms of the memory-guidance techniques common to both the cognitive and hypnosis interviews. Neither differential questioning time nor heightened subject or interviewer motivation could explain the results.

The Cognitive Interview was tested in the field to enhance the recollection of actual victims and witnesses of crime. The technique is based on laboratory-tested principles of memory retrieval, knowledge representation, and communication. Seven experienced detectives from the Metro-Dade Police Department were trained to use the technique and were compared with 9 untrained detectives. Before and after training, all detectives tape-recorded interviews with victims and witnesses of crime. The trained detectives elicited 47% more information after than before training, and 63% more information than did the untrained detectives. Overall collaboration rates (94%) were extremely high and were equivalent for pre- and posttrained interviews. Because the Cognitive Interview reliably enhances memory and is easily learned and administered, it should be useful for a variety of investigative interviews.

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