Richard I. Kemp

Recognizing Moving Faces: The Relative Contribution of Motion and Perspective View Information

Four experiments are reported that investigated the effects of motion on face recognition by comparing the recognition of moving, multiple static, and single static images of faces. The results of these experiments show that moving faces can be recognized more accurately than static faces, and this appears to be the case even if static cues can be employed to produce accurate recognition rates. The distinction between motion and perspective view information was investigated by manipulating the number and order in which multiple views of the same face were presented. The results obtained in these experiments suggest that the recognition advantage found for moving faces is not simply a product of the different angles of view which are contained in a moving face. Motion therefore appears to be an important source of information in recognizing a face, and probably aids in the derivation of 3-D structure.

Collaborative recall and collective memory: What happens when we remember together?

Studies of collective memory have traditionally been the domain of philosophers and sociologists, while cognitive psychologists have largely investigated memory at the level of the individual. However, within cognitive psychology there is a variety of psychological theories and experimental paradigms that have been used to study the process and outcomes of remembering in groups. In this paper we review the research on group remembering and draw together findings from different traditions. In doing so, we aim to answer a series of questions about the outcomes and consequences of recalling in groups, and the particular features of groups and of memories that may be conducive to the formation of a collective memory. In clarifying what we know and what is yet to be studied about group memory, we point the way forward for a cognitive psychological study of collective memory.

Co-witnesses talk: A survey of eyewitness discussion

Abstract The objective of this study was to obtain a quantitative measure of the discussion behaviour of real eyewitnesses. Undergraduate psychology students were given a questionnaire to determine if they had witnessed a serious event. Results from the questionnaire showed that the majority of respondents had witnessed a serious event at some point in their lives, and the majority of witnesses were not alone when they observed the event. Respondents who had experienced a serious event for which there was more than one witness present were invited to fill out a follow-up questionnaire. The follow-up study showed that when there is a co-witness present, most people (86%) report discussing the event with the co-witness. This is potentially problematic if the witnesses are contaminating one anothers memories of the event. The results are discussed in terms of psychological research and policy implications.

Passport Officers' Errors in Face Matching

Photo-ID is widely used in security settings, despite research showing that viewers find it very difficult to match unfamiliar faces. Here we test participants with specialist experience and training in the task: passport-issuing officers. First, we ask officers to compare photos to live ID-card bearers, and observe high error rates, including 14% false acceptance of ‘fraudulent’ photos. Second, we compare passport officers with a set of student participants, and find equally poor levels of accuracy in both groups. Finally, we observe that passport officers show no performance advantage over the general population on a standardised face-matching task. Across all tasks, we observe very large individual differences: while average performance of passport staff was poor, some officers performed very accurately – though this was not related to length of experience or training. We propose that improvements in security could be made by emphasising personnel selection.

Feedback training for facial image comparison

People are typically poor at matching the identity of unfamiliar faces from photographs. This observation has broad implications for face matching in operational settings (e.g., border control). Here, we report significant improvements in face matching ability following feedback training. In Experiment 1, we show cumulative improvement in performance on a standard test of face matching ability when participants were provided with trial-by-trial feedback. More important, Experiment 2 shows that training benefits can generalize to novel, widely varying, unfamiliar face images for which no feedback is provided. The transfer effect specifically benefited participants who had performed poorly on an initial screening test. These findings are discussed in the context of existing literature on unfamiliar face matching and perceptual training. Given the reliability of the performance enhancement and its generalization to diverse image sets, we suggest that feedback training may be useful for face matching in occupational settings.

Redesigning photo-ID to improve unfamiliar face matching performance

Viewers find it difficult to match photos of unfamiliar faces for identity. Despite this, the use of photographic ID is widespread. In this study we ask whether it is possible to improve face matching performance by replacing single photographs on ID documents with multiple photos or an average image of the bearer. In 3 experiments we compare photo-to-photo matching with photo-to-average matching (where the average is formed from multiple photos of the same person) and photo-to-array matching (where the array comprises separate photos of the same person). We consistently find an accuracy advantage for average images and photo arrays over single photos, and show that this improvement is driven by performance in match trials. In the final experiment, we find a benefit of 4-image arrays relative to average images for unfamiliar faces, but not for familiar faces. We propose that conventional photo-ID format can be improved, and discuss this finding in the context of face recognition more generally.

Error Rates in Users of Automatic Face Recognition Software

In recent years, wide deployment of automatic face recognition systems has been accompanied by substantial gains in algorithm performance. However, benchmarking tests designed to evaluate these systems do not account for the errors of human operators, who are often an integral part of face recognition solutions in forensic and security settings. This causes a mismatch between evaluation tests and operational accuracy. We address this by measuring user performance in a face recognition system used to screen passport applications for identity fraud. Experiment 1 measured target detection accuracy in algorithm-generated ‘candidate lists’ selected from a large database of passport images. Accuracy was notably poorer than in previous studies of unfamiliar face matching: participants made over 50% errors for adult target faces, and over 60% when matching images of children. Experiment 2 then compared performance of student participants to trained passport officers–who use the system in their daily work–and found equivalent performance in these groups. Encouragingly, a group of highly trained and experienced “facial examiners” outperformed these groups by 20 percentage points. We conclude that human performance curtails accuracy of face recognition systems–potentially reducing benchmark estimates by 50% in operational settings. Mere practise does not attenuate these limits, but superior performance of trained examiners suggests that recruitment and selection of human operators, in combination with effective training and mentorship, can improve the operational accuracy of face recognition systems.

Severe non-lethal violence during psychotic illness

Background: Research about violence in psychosis has mainly considered homicide by people with mental disorder, especially schizophrenia, and violence in groups of psychiatric patients. In this study we examine the characteristics of a sample of offenders with psychotic illness who committed severe non-lethal violent offences. Method: A review of court documents from a consecutive series of cases involving violence resulting in significant injury concluded in the District Court of New South Wales, Australia, in the years 2006 and 2007. Results; Of 661 people found to have committed a severe violent offence, 74 (11%, 95% confidence interval (CI) 9–14%) had a diagnosed psychotic illness. Of these, 16 (22%, 95% CI 12–31%) had never received treatment with antipsychotic medication and could be regarded as being in the first episode of psychosis. Offenders with psychosis were typically non-adherent to treatment, had co-morbid substance use and prior criminal convictions. Positive symptoms of psychotic illness such as hallucinations and delusional beliefs were reported to be present at the time of the offence in most of the cases. Seven of 74 (10%) psychotic offenders were found not guilty on the grounds of mental illness. Conclusions: People with psychotic illness are over-represented among those who commit violent offences resulting in significant injury, confirming the presence of an association between psychosis and severe non-lethal violence. Earlier treatment of first episode psychosis, improving the adherence to treatment of known patients and treatment of co-morbid substance abuse could reduce the incidence of severe violence committed by patients with psychosis.

The Impact of Eyewitness Expert Evidence and Judicial Instruction on Juror Ability to Evaluate Eyewitness Testimony

It has been argued that psychologists should provide expert evidence to help jurors discriminate between accurate and inaccurate eyewitness identifications. In this article we compare the effects of judicial instruction with expert evidence that is either congruent or incongruent with the ground truth, focusing on juror ability to evaluate “real” eyewitness evidence. In contrast to studies which have employed “fictional” eyewitness designs, we found no appreciable effect of either congruent or incongruent expert evidence on participant-juror sensitivity to eyewitness accuracy. We discuss the role of methodology on the inferences and conclusions that can be made regarding the impact of eyewitness expert evidence.

Sensitivity to feature displacement in familiar and unfamiliar faces : beyond the internal/external feature distinction

Previous studies of face recognition and of face matching have shown a general improvement for the processing of internal features as a face becomes more familiar to the participant. In this study, we used a psychophysical two-alternative forced-choice paradigm to investigate thresholds for the detection of a displacement of the eyes, nose, mouth, or ears for familiar and unfamiliar faces. No clear division between internal and external features was observed. Rather, for familiar (compared to unfamiliar) faces participants were more sensitive to displacements of internal features such as the eyes or the nose; yet, for our third internal feature—the mouth—no such difference was observed. Despite large displacements, many subjects were unable to perform above chance when stimuli involved shifts in the position of the ears. These results are consistent with the proposal that familiarity effects may be mediated by the construction of a robust representation of a face, although the involvement of attention in the encoding of face stimuli cannot be ruled out. Furthermore, these effects are mediated by information from a spatial configuration of features, rather than by purely feature-based information.