Visual comparison of two data sets: do people use the means and the variability?

In our everyday lives, we are required to make decisions based upon our statistical intuitions. Often, these involve the comparison of two groups, such as luxury versus family cars and their suitability. Research has shown that the mean difference affects judgements where two sets of data are compared, but the variability of the data has only a minor influence, if any at all. However, prior research has tended to present raw data as simple lists of values. Here, we investigated whether displaying data visually, in the form of parallel dot plots, would lead viewers to incorporate variability information. In Experiment 1, we asked a large sample of people to compare two fictional groups (children who drank ‘Brain Juice’ versus water) in a one-shot design, where only a single comparison was made. Our results confirmed that only the mean difference between the groups predicted subsequent judgements of how much they differed, in line with previous work using lists of numbers. In Experiment 2, we asked each participant to make multiple comparisons, with both the mean difference and the pooled standard deviation varying across data sets they were shown. Here, we found that both sources of information were correctly incorporated when making responses. Taken together, we suggest that increasing the salience of variability information, through manipulating this factor across items seen, encourages viewers to consider this in their judgements. Such findings may have useful applications for best practices when teaching difficult concepts like sampling variation

Familiarity and Within-Person Facial Variability: The Importance of the Internal and External Features

As faces become familiar, we come to rely more on their internal features for recognition and matching tasks. Here, we assess whether this same pattern is also observed for a card sorting task. Participants sorted photos showing either the full face, only the internal features, or only the external features into multiple piles, one pile per identity. In Experiments 1 and 2, we showed the standard advantage for familiar faces—sorting was more accurate and showed very few errors in comparison with unfamiliar faces. However, for both familiar and unfamiliar faces, sorting was less accurate for external features and equivalent for internal and full faces. In Experiment 3, we asked whether external features can ever be used to make an accurate sort. Using familiar faces and instructions on the number of identities present, we nevertheless found worse performance for the external in comparison with the internal features, suggesting that less identity information was available in the former. Taken together, we show that full faces and internal features are similarly informative with regard to identity. In comparison, external features contain less identity information and produce worse card sorting performance. This research extends current thinking on the shift in focus, both in attention and importance, toward the internal features and away from the external features as familiarity with a face increases

Do professional facial image comparison training courses work?

Facial image comparison practitioners compare images of unfamiliar faces and decide whether or not they show the same person. Given the importance of these decisions for national security and criminal investigations, practitioners attend training courses to improve their face identification ability. However, these courses have not been empirically validated so it is unknown if they improve accuracy. Here, we review the content of eleven professional training courses offered to staff at national security, police, intelligence, passport issuance, immigration and border control agencies around the world. All reviewed courses include basic training in facial anatomy and prescribe facial feature (or 'morphological') comparison. Next, we evaluate the effectiveness of four representative courses by comparing face identification accuracy before and after training in novices (n = 152) and practitioners (n = 236). We find very strong evidence that short (1-hour and half-day) professional training courses do not improve identification accuracy, despite 93% of trainees believing their performance had improved. We find some evidence of improvement in a 3-day training course designed to introduce trainees to the unique feature-by-feature comparison strategy used by facial examiners in forensic settings. However, observed improvements are small, inconsistent across tests, and training did not produce the qualitative changes associated with examiners' expertise. Future research should test the benefits of longer examination-focussed training courses and incorporate longitudinal approaches to track improvements caused by mentoring and deliberate practice. In the absence of evidence that training is effective, we advise agencies to explore alternative evidence-based strategies for improving the accuracy of face identification decisions

Hyper-realistic Face Masks in a Live Passport-Checking Task

Hyper-realistic face masks have been used as disguises in at least one border crossing and in numerous criminal cases. Experimental tests using these masks have shown that viewers accept them as real faces under a range of conditions. Here, we tested mask detection in a live identity verification task. Fifty-four visitors at the London Science Museum viewed a mask wearer at close range (2 m) as part of a mock passport check. They then answered a series of questions designed to assess mask detection, while the masked traveller was still in view. In the identity matching task, 8% of viewers accepted the mask as matching a real photo of someone else, and 82% accepted the match between masked person and masked photo. When asked if there was any reason to detain the traveller, only 13% of viewers mentioned a mask. A further 11% picked disguise from a list of suggested reasons. Even after reading about mask-related fraud, 10% of viewers judged that the traveller was not wearing a mask. Overall, mask detection was poor and was not predicted by unfamiliar face matching performance. We conclude that hyper-realistic face masks could go undetected during live identity checks

UNSW face test: a screening tool for super-recognizers

We present a new test–the UNSW Face Test (www.unswfacetest.com)–that has been specifically designed to screen for super-recognizers in large online cohorts and is available free for scientific use. Super-recognizers are people that demonstrate sustained performance in the very top percentiles in tests of face identification ability. Because they represent a small proportion of the population, screening large online cohorts is an important step in their initial recruitment, before confirmatory testing via standardized measures and more detailed cognitive testing. We provide normative data on the UNSW Face Test from 3 cohorts tested via the internet (combined n = 23,902) and 2 cohorts tested in our lab (combined n = 182). The UNSW Face Test: (i) captures both identification memory and perceptual matching, as confirmed by correlations with existing tests of these abilities; (ii) captures face-specific perceptual and memorial abilities, as confirmed by non-significant correlations with non-face object processing tasks; (iii) enables researchers to apply stricter selection criteria than other available tests, which boosts the average accuracy of the individuals selected in subsequent testing. Together, these properties make the test uniquely suited to screening for super-recognizers in large online cohorts

Masked face identification is improved by diagnostic feature training

To slow the spread of COVID-19, many people now wear face masks in public. Face masks impair our ability to identify faces, which can cause problems for professional staff who identify offenders or members of the public. Here, we investigate whether performance on a masked face matching task can be improved by training participants to compare diagnostic facial features (the ears and facial marks)—a validated training method that improves matching performance for unmasked faces. We show this brief diagnostic feature training, which takes less than two minutes to complete, improves matching performance for masked faces by approximately 5%. A control training course, which was unrelated to face identification, had no effect on matching performance. Our findings demonstrate that comparing the ears and facial marks is an effective means of improving face matching performance for masked faces. These findings have implications for professions that regularly perform face identification

Charts and fingerprints: A match made in court

Forensic fingerprint evidence is considered irrefutable by fingerprint examiners, and despite a lack of peer-reviewed empirical research confirming the accuracy, validity and reliability of fingerprinting methods, fingerprint evidence has been used in court for more than a century. One of the options that has been proposed to improve the quality of fingerprint testimony is to limit the role of fingerprint experts, and allow jurors to match fingerprints. This study examined whether court charts (i.e., fingerprints with corresponding features highlighted) improve novices' ability to discriminate between matching and non-matching prints, and whether court charts produce a response bias to say “match”. Forty-two undergraduates were presented with pairs of fingerprints and asked to decide whether they matched or not. Half the fingerprints were presented as court charts, and the remaining prints were presented with no markings. We found that court charts do not improve novices' ability to discriminate between matching and non-matching fingerprints, and that they do not produce a response bias to say “match”. Therefore, our results suggest that court charts do not affect jurors' judgements about fingerprint evidence

Applied face matching systems

<p>Many security procedures rely on identification of unfamiliar people, e.g. when issuing photo-ID documents and when identifying criminals in forensic investigations. In these applied settings, identification decisions are often distributed across multiple humans and computers in complex face matching <em>systems</em>. This figure outlines examples of two such systems.<br></p

Match me if you can: Evaluating professional training for facial image comparison

Verifying the identity of an unfamiliar person by examining their face is a surprisingly error-prone task – approximately one in every four decisions made will be incorrect. Despite this high error-rate, unfamiliar face matching tasks form the basis of many important applied forensic and security procedures. To mitigate the risk of errors on face matching tasks, professional facial comparison staff undergo training to improve their ability. Although specifically designed to improve facial identification accuracy, the content, structure and effectiveness of these training courses is unknown and untested. The work reported in this thesis therefore investigates whether current professional training techniques successfully improve face matching accuracy.A review of professional training courses revealed that trainees are typically taught facial anatomy, principles of photography, and are encouraged to make featural comparisons. Practical exercises where trainees receive feedback on the accuracy of their decisions are also common. Although the psychology literature indicates that these methods could be effective, there is a lack of empirical evidence. Thus, a series of eleven experiments validated each of the aforementioned facial identification training techniques.These experiments indicated that facial anatomy and forensic photography training do not improve face matching ability, and neither does morphological classification – a type of featural processing where facial features are classified and compared according to pre-defined categories. Feedback training and facial feature similarity judgements were however, more successful. Feedback training resulted in a long-lasting improvement in observers’ ability to detect non-matching identities, and rating facial feature similarity resulted in an increased ability to detect matching identities. The feature similarity ratings themselves were predictive of identity, and when aggregated across individuals, resulted in almost perfect discrimination. Trained facial examiners also outperformed novices by using a qualitatively different strategy, characterised by an increased reliance on featural face processing.The findings in this thesis not only contribute to our understanding of how to improve performance on this difficult perceptual task, but are also informative of the cognitive processes underlying face matching decisions. The training methods identified in this thesis provide the opportunity for organisations to adopt evidence-based training procedures for staff performing security-critical face matching tasks