To improve police techniques for interviewing witnesses, a procedure - the cognitive interview - was developed based on scientific principles of memory.
Using this technique, police instruct witnesses to try to reconstruct the environment surrounding the original event and the accompanying feelings and reactions, to report everything without editing, to adopt different perspectives, and to report events in different orders. Subsequent studies broadened the technique for use with child witnesses and resulted in a revised procedure based on the principles of memory-event similarity, focused retrieval, extensive retrieval, and witness-compatible questioning. In a laboratory study, the revised technique elicited approximately 45 percent more information than the original technique, which had been shown previously to be 30 to 35 percent more effective than a standard witness interview. In a field study, police detectives trained in the revised technique collected 63 percent more information than untrained detectives, although the two groups had been equivalent prior to training. Further, the additional information was highly accurate. Results show that the cognitive interviewing technique reliably enhances the completeness of witness recollection without increasing the number of incorrect or confabulated bits of information generated. 9 references.