Effects of Lineup Members' Facial Characteristics and Demeanour on Eyewitness Identification Performance

Author: Tomoko Nishizawa

Nishizawa, Tomoko, 2015 Effects of Lineup Members' Facial Characteristics and Demeanour on Eyewitness Identification Performance, Flinders University, School of Psychology

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The composition of a police lineup can affect the accuracy of identification decisions made by witnesses. This has been demonstrated, for example, by experimental manipulations of variables such as lineup functional size, suspect-filler similarity and the closeness of the match between a suspect and a witness' description of the culprit. This thesis investigated whether other characteristics of lineup members, such as how familiar, distinctive and memorable they appeared, affected witnesses' perceptions of the likelihood that a particular member was the culprit, perceptions that might affect the likelihood of false identifications of innocent suspects or incorrect rejections of culprits. Experiments 1 and 2 explored the possibility that a smile displayed by an innocent suspect in a photospread may arouse a sense of familiarity, biasing the photospread against the suspect and increasing the risk of false identifications. Although a smile consistently aroused a sense of familiarity, Experiments 1 and 2 provided mixed results regarding its effect on witnesses' perceptions of the degree of resemblance between the suspect and the culprit. Using an odd-looking smile, Experiment 3 unexpectedly showed the reverse effect, with the smile making the innocent suspect appear unfamiliar, leading to the perception that the suspect was unlikely to be the culprit. Experiment 4 demonstrated that, in addition to inducing unfamiliarity, an odd smile on the face of the culprit in a photospread made the culprit appear distinctive and memorable, leading to witnesses perceiving the culprit presented in the lineup as an unlikely match to be the culprit. Experiments 5 and 6 manipulated the perceived distinctiveness, memorability and unfamiliarity of the culprit using various other cues to explore further how such perceptions might contribute to the culprit presented in a photospread being falsely perceived as an unlikely match to be the culprit. That is, encoding conditions were such that participants could not see all of the culprit's face. Later they viewed a photospread containing the culprit, who had a prominent physical feature (e.g., beard, tattoo) on the previously concealed part of his or her face. The presentation of the physical feature increased the likelihood of an inaccurate perception that the culprit presented in the lineup was not the actual culprit, particularly when participants felt certain that the culprit did not have the feature. Taken together, these studies indicate that the facial characteristics and the demeanour of the suspect or the culprit in a lineup have the potential to affect the accuracy of eyewitness identifications. For example, the presence of some cue that makes an innocent suspect appear familiar may increase the risk of false identifications. Conversely, if for some reason, a culprit appears unexpectedly more memorable than the witnesses' memory of that person, the risk of incorrect rejections may increase.

Keywords: Biased lineups,Eyewitness Identifications,Facial Characteristics,Familiarity,Memorability

Subject: Psychology thesis

Thesis type: Doctor of Philosophy
Completed: 2015
School: School of Psychology
Supervisor: Prof Neil Brewer