Interference in facial memory from exposure to misleading composite pictures
The literature on interference effects in facial memory indicates that interference to witness memory may be caused by three factors in the interval between observation of a target person and a later attempt to identify that person in a lineup. The first arises from the examination of a sequence of mugshots prior to an attempt to identify the target. The second arises again from the examination of mugshots, but in this instance a face or faces from the mugshot sequence appears in the final lineup. The third type of interference occurs as a result of the subject being exposed to misleading information either in the form of a questionnaire or a statement allegedly written by another witness in the interval between observation and test (post-event information). This thesis examines another potential source of interference in facial memory: that caused by observing composite pictures of a target person prior to making a description and selecting that person in a lineup. Six studies are reported in which subjects observed an incident involving a target male and subsequently attempted to remember the appearance of the person involved. Post-event information was introduced, in the form of a Photofit picture of the target, which was either consistent or inconsistent with the appearance of the target. In the consistent information condition, subjects received an Accurate Photofit, made to resemble the target as closely as possible. In the inconsistent information condition, subjects received one of two misleading Photofits in which one feature in each was deliberately erroneous: typically, in one the target's hair was altered, while in the other, a moustache was added. A Control condition received no composite between observation and test. In Experiment 1, experimental subjects exposed to a misleading composite were significantly more likely to be misled in their recall of the target's appearance than were control subjects who saw either an accurate composite or no composite at all. In Experiment 2, this finding was replicated and extended by showing that the misleading information also biased experimental subjects' recognition performance in their choice of person from a photospread. There was no tendency for the influence of the misleading composites to increase with a delay in testing of up to one week. What appeared more critical was the time at which the composites were presented: presenting them just prior to test and after the retention interval increased interference compared to conditions in which the misleading information immediately followed observation of the incident and preceded the retention interval. Experiment 3 involved a further replication of these findings, but with the target being seen by subjects live as part of an unexpected incident rather than in a videotape. The findings confirmed those of the two previous studies for both recall and recognition performance. In addition, this experiment examined the influence of a blatantly erroneous composite upon performance. Previous research (Loftus, 1979b) indicated that this blatantly erroneous information would be uniformly rejected by subjects. Contrary to prediction, however, it was found that recall and recognition performance were as successfully influenced by this composite as by the two more subtly misleading versions. A resolution of these discrepant findings was suggested. The final three experiments explored ways in which resistance to the misleading composite information might be induced. It has been suggested (Loftus, 1981b; Yuille, 1984) that the degree of attention to the witnessed event is an important factor in influencing susceptibility to suggestion. Yuille (1984) hypothesised that post-event information will only be effective in influencing memory if it refers to a non-salient detail to which the subject failed to attend. This hypothesis was explored in Experiments 4 and 5. In Experiment 4, length of exposure to the target was increased and in Experiment 5, a cued recall questionnaire, concerning the details of the witnessed incident, was instituted prior to the presentation of the post-event information. Previous research has shown that both increased exposure duration and prior recall enhance later performance. It was observed that both manipulations significantly reduced or eliminated interference in recall and recognition, a finding interpreted as supporting the attentional hypothesis. Experiment 5 also had implications for a theoretical understanding of the action of post-event information upon memory. Two hypotheses have been advocated to account for the interference effects. The first hypothesis holds that post-event information actually alters and permanently updates the original memory trace so that it is lost from storage. The second hypothesis holds that the post-event information co-exists with the original memory, which remains intact in the system, and simply renders it less accessible, although still available given the appropriate retrieval cues.