The time course of processing external and internal features of unfamiliar faces

The time course of processing internal and external facial features was studied in a sequential face matching task, where first a target face was presented, followed by a test face. The exposure duration of the test face was varied systematically (90, 120, 150 ms, and self-paced). In three tasks, participants were instructed to match either the whole face, only external features, or only internal features of the target and test face. Taken together, the results in all the three tasks provide evidence for very fast matching processes. For upright faces, maximal performance was achieved at 90 ms exposure duration and longer exposure durations (120, 150 ms, self-paced) did not improve accuracy. For inverted whole faces, reduced exposure duration resulted in an increase of matching errors, suggesting that below 150 ms of exposure duration, inverted faces cannot be matched reliably. When matching selected facial features only, no such inversion effect was found. Our data challenges previous claims that external features are matched faster than internal: no difference of time course was found between external and internal features. However, external features were matched more accurately.     

Face averages and multiple images in a live matching task

We know from previous research that unfamiliar face matching (determining whether two simultaneously presented images show the same person or not) is very error-prone. A small number of studies in laboratory settings have shown that the use of multiple images or a face average, rather than a single image, can improve face matching performance. Here, we tested 1,999 participants using four-image arrays and face averages in two separate live matching tasks. Matching a single image to a live person resulted in numerous errors (79.9% accuracy across both experiments), and neither multiple images (82.4% accuracy) nor face averages (76.9% accuracy) improved performance. These results are important when considering possible alterations which could be made to photo-ID. Although multiple images and face averages have produced measurable improvements in performance in recent laboratory studies, they do not produce benefits in a real-world live face matching context.     

Motivational Incentives Improve Unfamiliar Face Matching Accuracy

Unfamiliar face matching is the process of simultaneously verifying the equivalence of two faces. Accuracy within this task is crucial given its importance and prevalence in security domains. However, research has consistently demonstrated that unfamiliar face matching is error prone, suggesting the need for improvement techniques. Motivational incentives have been shown to reliably enhance performance on a wide array of cognitive tasks. Therefore, the current study examined the effect of motivational incentives on unfamiliar face matching. Experiment 1 showed increased accuracy in mismatch trials with the addition of a motivational incentive. The improvement was associated with an increase in reaction time and bias towards making a mismatch response. This bias, however, did not produce a decrease in accuracy on match trials. Experiment 2 replicated this result with a more ecologically valid methodology. The results suggest motivational incentives to be effective at improving performance on mismatch trials, arguably the most important aspect of real‐world unfamiliar face matching. Copyright © 2013 John Wiley & Sons, Ltd.     

Smiles in face matching: Idiosyncratic information revealed through a smile improves unfamiliar face matching performance

Unfamiliar face matching is a surprisingly difficult task, yet we often rely on people's matching decisions in applied settings (e.g., border control). Most attempts to improve accuracy (including training and image manipulation) have had very limited success. In a series of studies, we demonstrate that using smiling rather than neutral pairs of images brings about significant improvements in face matching accuracy. This is true for both match and mismatch trials, implying that the information provided through a smile helps us detect images of the same identity as well as distinguishing between images of different identities. Study 1 compares matching performance when images in the face pair display either an open-mouth smile or a neutral expression. In Study 2, we add an intermediate level, closed-mouth smile, to identify the effect of teeth being exposed, and Study 3 explores face matching accuracy when only information about the lower part of the face is available. Results demonstrate that an open-mouth smile changes the face in an idiosyncratic way which aids face matching decisions. Such findings have practical implications for matching in the applied context where we typically use neutral images to represent ourselves in official documents.     

Effects of Image Preprocessing on Face Matching and Recognition in Human Observers

In person identification, recognition failure due to variations of illumination is common. In this study, we employed image‐processing techniques to tackle this problem. Participants performed recognition and matching tasks where the face stimuli were either original images or computer‐processed images in which shading was weakened via a number of image‐processing techniques. The results show that whereas recognition accuracy in a memory task was unaffected, some of the techniques significantly improved the identification performance in a face‐matching task. We conclude that relative to long‐term face memory, face matching is more susceptible to discrepancy of shading in different images of a face. Reducing the discrepancy by certain preprocessing techniques can facilitate person identification when original face images contain large illumination differences. Copyright © 2013 John Wiley & Sons, Ltd.     

Face processing skills predict faithfulness of portraits drawn by novices

Individuals show astonishing variability in their face recognition abilities, and the causes and consequences of this heterogeneity are unclear. Special expertise with faces, for example in portraitists, is associated with advantages on face processing tasks, especially those involving perceptual abilities. Do face processing skills improve through practice, or does drawing skill reflect pre-existing individual differences? If the latter, then the association between face processing skills and production of faithful portraits should also exist in people without practice in drawing. Two exploratory studies and one follow-up confirmatory study provide support for this hypothesis. Drawing ability of novices was predicted by their performance on face recognition tasks involving perceptual discrimination and visual short-term memory, but not by those that rely more heavily on long-term memory or memory for non-face objects. By examining non-experts, we show that expertise with faces might build upon pre-existing individual differences in face processing skills.     

Super-Recognisers show an advantage for other race face identification

The accurate identification of an unfamiliar individual from a face photo is a critical factor in several applied situations (e.g., border control). Despite this, matching faces to photographic ID is highly prone to error. In lieu of effective training measures, which could reduce face matching errors, the selection of “super-recognisers” (SRs) provides the most promising route to combat misidentification or fraud. However, to date, super-recognition has been defined and tested using almost exclusively “own-race” face memory and matching tests. Here, across three studies, we test Caucasian participants' performance on own- and other-race face identification tasks (GFMT, MFMT, CFMT+, EFMT, CFMT-Chinese). Our findings show that compared to controls, high-performing typical recognisers (Studies 1 and 2) and SRs (Study 3) show superior performance on both the own- and other-race tests. These findings suggest that recruiting SRs in ethnically diverse applied settings could be advantageous.     

Eye-witnesses should not do cryptic crosswords prior to identity parades

Navon letter tasks have been shown to affect subsequent face recognition performance. As such tasks are not likely to by carried out prior to a witness attending an identity parade this is unlikely to have much applied relevance. Here, however, it is explored how a range of puzzles that witnesses might engage in affect face recognition. Cryptic crosswords were found to have a detrimental effect on subsequent face recognition, unlike reading, literal crosswords, or sudoku. As well as this finding's practical importance, it also provides a further insight into the Navon effect on face processing.     

Checking ID‐cards for the sale of restricted goods: Age decisions bias face decisions

Matching unfamiliar faces is highly error‐prone, and most studies highlight the implications for real‐world ID‐checking. Here we study a particular instance of ID‐checking: proof of age for buying restricted goods such as alcohol. In this case, checkers must establish that an identity document is carried by its legitimate owner (i.e., that the ID photo matches the face of the bearer) and that the ID proves the bearer to be old enough to make the purchase. Across three experiments, using two common forms of photo‐ID (i.e., driving licenses, PASS+ cards) we show that observers produce very high error rates when age requirements are met, but faces mismatch. This bias away from detecting a face mismatch remained evident in experienced cashiers—though to a somewhat attenuated level. We discuss interactions between face matching and other tasks, and the practical consequences of a bias which favours those using photo‐ID with fraudulent intent.     

Holistic processing and reliance on global viewing strategies in older adults' face perception

There is increasing evidence that face recognition might be impaired in older adults, but it is unclear whether the impairment is truly perceptual, and face specific. In order to address this question we compared performance in same/different matching tasks with face and non-face objects (watches) among young (mean age 23.7) and older adults (mean age 70.4) using a context congruency paradigm (Meinhardt-Injac, Persike & Meinhardt, 2010, Meinhardt-Injac, Persike and Meinhardt, 2011a). Older adults were less accurate than young adults with both object classes, while face matching was notably impaired. Effects of context congruency and inversion, measured as the hallmarks of holistic processing, were equally strong in both age groups, and were found only for faces, but not for watches. The face specific decline in older adults revealed deficits in handling internal facial features, while young adults matched external and internal features equally well. Comparison with non-face stimuli showed that this decline was face specific, and did not concern processing of object features in general. Taken together, the results indicate no age-related decline in the capabilities to process faces holistically. Rather, strong holistic effects, combined with a loss of precision in handling internal features indicate that older adults rely on global viewing strategies for faces. At the same time, access to the exact properties of inner face details becomes restricted.     

The Effect of Feedback on Face‐Matching Accuracy

In face matching, observers have to decide if two photographs depict the same person or different people. This is a remarkably difficult task, so the current study investigated whether it can be improved when observers receive feedback for their performance. In five experiments, observers' initial matching performance was recorded before feedback for their accuracy was administered across three blocks. Improvements were then assessed with faces that had been seen previously with or without feedback and with completely new, previously unseen faces. In all experiments, feedback failed to improve face‐matching accuracy. However, trial‐by‐trial feedback helped to maintain accuracy at baseline level after feedback was withdrawn again, even with new faces (Experiments 1–3). By contrast, when no feedback was given throughout the experiment (Experiments 1–3) or when outcome feedback was administered at the end of blocks (Experiments 4 and 5), a continuous decline in matching accuracy was found, whereby observers found it increasingly difficult to tell different facial identities apart. A sixth experiment showed that this decline in accuracy continues throughout when the matching task is prolonged substantially. Together, these findings indicate that observers find it increasingly difficult to differentiate faces in matching tasks over time, but trial‐by‐trial feedback can help to maintain accuracy. The theoretical and practical implications of these findings are discussed. Copyright © 2013 John Wiley & Sons, Ltd.     

Age-related differences in face processing: a meta-analysis of three functional neuroimaging experiments.

Differences between young and old adults in brain activity, measured with positron emission tomography, were examined during three face processing experiments: episodic memory, working memory, and degraded face perception. Each experiment contained an easy face matching condition and a more difficult processing condition. Young adults showed greater activity in bilateral prefrontal cortex during the memory tasks, compared to face matching, but no difference in prefrontal activity between degraded and nondegraded perception. Older adults, on the other hand, had greater prefrontal activity in both memory and degraded perceptual tasks compared to matching. This suggests that increased prefrontal activity is task-specific in young adults, but, in old adults, is a more general response to increased cognitive effort or need for resources. These data are consistent with the dedifferentiation hypothesis of aging, and suggest a possible neural mechanism for this dedifferentiation, such that dependence on prefrontal activity across a greater number of tasks could also increase the amount of covariance across these tasks.     

Matching Face Images Taken on the Same Day or Months Apart: the Limitations of Photo ID

It is well‐established that matching images of unfamiliar faces is rather error prone. However, there is an important mismatch between face matching in laboratory and realistic settings. All of the currently available face‐matching databases were designed to establish the baseline level of unfamiliar face perception. Therefore, target and test images for each face identity have been taken on the same day, minimizing within‐face variations. In realistic settings, on the other hand, faces do vary, even day to day. This study examined the proficiency of matching images of unfamiliar faces, which were taken on the same day or months apart. In two experiments, same‐day images were matched substantially more accurately and faster than different‐date photographs using the standard 1‐in‐10 and pairwise face‐matching tasks. This suggests that experimental studies on face matching underestimate its difficulty in real‐world situations. Photographs of unfamiliar faces seem to be unreliable proofs of identity, especially if the ID documents do not use very recent images of the holders. Copyright © 2013 John Wiley & Sons, Ltd.     

Functional neuroimaging studies of category specificity in object recognition: a critical review and meta-analysis

Functional neuroimaging studies in which the cortical organization for semantic knowledge has been addressed have revealed interesting dissociations in the recognition of different object categories, such as faces, natural objects, and manufactured objects. The present paper critically reviews these studies and performs a meta-analysis of stereotactic coordinates to determine whether category membership predicts patterns of brain activation across different studies. This meta-analysis revealed that, in the ventral temporal cortex, recognition of manufactured objects activates more medial aspects of the fusiform gyrus, as compared with natural object or face recognition. Face recognition activates more inferior aspects of the ventral temporal cortex, as compared with manufactured object recognition. The recognition task used—viewing, matching, or naming—also predicted brain activation patterns. Specifically, matching tasks recruit more inferior occipital regions than do either naming or viewing tasks, whereas naming tasks recruit more anterior ventral temporal sites than do either viewing or matching tasks. These findings indicate that the cognitive demands of a particular recognition task are as predictive of cortical activation patterns as is category membership.     

Developmental changes in face processing skills

Expertise in processing differences among faces in the spacing among facial features (second-order relations) is slower to develop than expertise in processing the shape of individual features or the shape of the external contour. To determine the impact of the slow development of sensitivity to second-order relations on various face-processing skills, we developed five computerized tasks that require matching faces on the basis of identity (with changed facial expression or head orientation), facial expression, gaze direction, and sound being spoken. In Experiment 1, we evaluated the influence of second-order relations on performance on each task by presenting them to adults (N=48) who viewed the faces either upright or inverted. Previous studies have shown that inversion has a larger effect on tasks that require processing the spacing among features than it does on tasks that can be solved by processing the shape of individual features. Adults showed an inversion effect for only one task: matching facial identity when there was a change in head orientation. In Experiment 2, we administered the same tasks to children aged 6, 8, and 10 years (N=72). Compared to adults, 6-year-olds made more errors on every task and 8-year-olds made more errors on three of the five tasks: matching direction of gaze and the two facial identity tasks. Ten-year-olds made more errors than adults on only one task: matching facial identity when there was a change in head orientation (e.g., from frontal to tilted up). Together, the results indicate that the slow development of sensitivity to second-order relations causes children to be especially poor at recognizing the identity of a face when it is seen in a new orientation.     

Super‐recognisers in Action: Evidence from Face‐matching and Face Memory Tasks

Individuals employed in forensic or security settings are often required to compare faces of ID holders to document photographs, or to recognise the faces of suspects in closed‐circuit television footage. It has long been established that both tasks produce a high error rate amongst typical perceivers. This study sought to determine the performance of individuals with exceptionally good face memory (‘super‐recognisers’) on applied facial identity matching and memory tasks. In experiment 1, super‐recognisers were significantly better than controls when matching target faces to simultaneously presented line‐ups. In experiment 2, super‐recognisers were also better at recognising faces from video footage. These findings suggest that super‐recognisers are more accurate at face matching and face memory tasks than typical perceivers, and they could be valuable expert employees in national security and forensic settings. © 2015 The Authors Applied Cognitive Psychology Published by John Wiley & Sons Ltd.     

The effect of inversion on the encoding of normal and “thatcherized” faces

In the “Thatcher illusion” a face, in which the eyes and mouth are inverted relative to the rest of the face, looks grotesque when shown upright but not when inverted. In four experiments we investigated the contribution of local and global processing to this illusion in normal observers. We examined inversion effects (i.e., better performance for upright than for inverted faces) in a task requiring discrimination of whether faces were or were not “thatcherized”. Observers made same/different judgements to isolated face parts (Experiments 1-2) and to whole faces (Experiments 3-4). Face pairs had the same or different identity, allowing for different process- ing strategies using feature-based or configural information, respectively. In Experiment 1, feature-based matching of same-person face parts yielded only a small inversion effect for normal face parts. However, when feature-based matching was prevented by using the face parts of different people on all trials (Experiment 2) an inversion effect occurred for normal but not for thatcherized parts. In Experiments 3 and 4, inversion effects occurred with normal but not with thatcherized whole faces, on both same- and different-person matching tasks. This suggests that a common configural strategy was used with whole (normal) faces. Face context facilitated attention to misoriented parts in same-person but not in different-person matching. The results indicate that (1) face inversion disrupts local configural processing, but not the processing of image features, and (2) thatcherization disrupts local configural processing in upright faces.     

Hemisphere-dependent holistic processing of familiar faces

In two behavioral experiments involving lateralized stimulus presentation, we tested whether one of the most commonly used measures of holistic face processing—the composite face effect—would be more pronounced for stimuli presented to the right as compared to the left hemisphere. In experiment 1, we investigated the composite face effect in a verbal identification task, similar to its original report (Young, Hellawell, & Hay, 1987). Aligning top and bottom halves of composite face stimuli led to performance decreases irrespective of hemifield, indicating holistic processing of comparable magnitude for inputs provided separately to either hemisphere. However, when matching of the same top parts was required in experiment 2, an alignment-dependent performance decrease was found for stimuli presented in the left, but not right visual field. These observations suggest that the right hemisphere dominates in early stages of holistic processing, as indexed by the composite face effect, but that later processes such as face identification and naming are based on unified representations that are independent of input lateralization. Moreover, the composite face effect may not rely on the exact same representation(s) when measured in matching and identification tasks.     

The Effect of Image Pixelation on Unfamiliar‐Face Matching

Low‐resolution, pixelated images from closed‐circuit television (CCTV) can be used to compare the perpetrators of crime with high‐resolution photographs of potential suspects. The current study investigated the accuracy of person identification under these conditions, by comparing high‐resolution and pixelated photographs of unfamiliar faces in a series of matching tasks. Performance decreased gradually with different levels of pixelation and was close to chance with a horizontal image resolution of only 8 pixels per face (Experiment 1). Matching accuracy could be improved by reducing the size of pixelated faces (Experiment 2) or by varying the size of the to‐be‐compared‐with high‐resolution face image (Experiment 3). In addition, pixelation produced effects that appear to be separable from other factors that might affect matching performance, such as changes in face view (Experiment 4). These findings reaffirm that criminal identifications from CCTV must be treated with caution and provide some basic estimates for identification accuracy with different pixelation levels. This study also highlights potential methods for improving performance in this task. Copyright © 2013 John Wiley & Sons, Ltd.