Recognising faces seen alone or with others: when two heads are worse than one

There is a large body of work investigating face identification, but most of this addresses recognition of a single person. Here, we examine how recognition is affected by the presence of a second face. In Experiments 1 and 2, we demonstrate that memory for an unfamiliar face is severely reduced if it is seen alongside a second person. Sequential presentation of two target faces further reduces accuracy. In Experiments 3 and 4, we demonstrate the same disadvantage for two‐face targets in a matching task, where subjects have no time limits or memory requirement. In matching, the damaging effect of a second face is greatest when the targets are placed close together. Furthermore, there is a general advantage for faces presented to the left. We suggest that it may not be possible to extrapolate results from single‐face studies to experiments (or realistic situations) involving more than one person. Copyright © 2006 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.     

Face-to-face interference in typical and atypical development

Visual communication cues facilitate interpersonal communication. It is important that we look at faces to retrieve and subsequently process such cues. It is also important that we sometimes look away from faces as they increase cognitive load that may interfere with online processing. Indeed, when typically developing individuals hold face gaze it interferes with task completion. In this novel study we quantify face interference for the first time in Williams syndrome (WS) and Autism Spectrum Disorder (ASD). These disorders of development impact on cognition and social attention, but how do faces interfere with cognitive processing? Individuals developing typically as well as those with ASD (n = 19) and WS (n = 16) were recorded during a question and answer session that involved mathematics questions. In phase 1 gaze behaviour was not manipulated, but in phase 2 participants were required to maintain eye contact with the experimenter at all times. Looking at faces decreased task accuracy for individuals who were developing typically. Critically, the same pattern was seen in WS and ASD, whereby task performance decreased when participants were required to hold face gaze. The results show that looking at faces interferes with task performance in all groups. This finding requires the caveat that individuals with WS and ASD found it harder than individuals who were developing typically to maintain eye contact throughout the interaction. Individuals with ASD struggled to hold eye contact at all points of the interaction while those with WS found it especially difficult when thinking.     

In the Dock: Chimeric Image Composites Reduce Identification Accuracy

The aim of presenting chimeric images (formed from opposing halves of a pair of same or different faces) in court settings is to optimise the accuracy of identification decisions based on CCTV evidence. The experiments reported here examined the utility of this technique. Experiment 1 examined the accuracy of face matching with vertically split, aligned chimeric images, misaligned hemi‐faces and full‐face images. Experiment 2 replicated the first experiment but replaced the misaligned images with opposing hemi‐faces separated by a gap. The final experiment used horizontally split faces. All three experiments showed that matching was less accurate with aligned chimeric images than with full‐face images. Furthermore, the pattern of responses obtained with chimeric images differed significantly from full‐face matching and misaligned/separated hemi‐face matching. Chimeric images produced a bias towards same responses even when the face halves were different. The results suggest caution in the use of chimeric images in court. Copyright © 2011 John Wiley & Sons, Ltd.     

The role of active exploration of 3D face stimuli on recognition memory of facial information

Research on face recognition has mainly relied on methods in which observers are relatively passive viewers of face stimuli. This study investigated whether active exploration of three-dimensional (3D) face stimuli could facilitate recognition memory. A standard recognition task and a sequential matching task were employed in a yoked design. Observers in the active condition explored 3D views of faces via a mouse or joystick during the training and test sessions of the task, whereas observers in the passive condition simply viewed the replay of the same sequence of face stimuli generated by the active observers. It was found that the active condition produced better recognition accuracy than the passive condition. The study provides the first evidence that active exploration of 3D face stimuli can lead to better face recognition memory and matching performance.     

Event-related potentials reveal the development of stable face representations from natural variability

Natural variability between instances of unfamiliar faces can make it difficult to reconcile two images as the same person. Yet for familiar faces, effortless recognition occurs even with considerable variability between images. To explore how stable face representations develop, we employed incidental learning in the form of a face sorting task. In each trial, multiple images of two facial identities were sorted into two corresponding piles. Following the sort, participants showed evidence of having learnt the faces performing more accurately on a matching task with seen than with unseen identities. Furthermore, ventral temporal event-related potentials were more negative in the N250 time range for previously seen than for previously unseen identities. These effects appear to demonstrate some degree of abstraction, rather than simple picture learning, as the neurophysiological and behavioural effects were observed with novel images of the previously seen identities. The results provide evidence of the development of facial representations, allowing a window onto natural mechanisms of face learning.     

Face learning with multiple images leads to fast acquisition of familiarity for specific individuals

Matching unfamiliar faces is a difficult task. Here we ask whether it is possible to improve performance by providing multiple images to support matching. In two experiments we observe that accuracy improves as viewers are provided with additional images on which to base their match. This technique leads to fast learning of an individual, but the effect is identity-specific: Despite large improvements in viewers’ ability to match a particular person's face, these improvements do not generalize to other faces. Experiment 2 demonstrated that trial-by-trial feedback provided no additional benefits over the provision of multiple images. We discuss these results in terms of familiar and unfamiliar face processing and draw out some implications for training regimes.     

Searching for faces in crowd chokepoint videos

Investigations of face identification have typically focussed on matching faces to photographic IDs. Few researchers have considered the task of searching for a face in a crowd. In Experiment 1, we created the Chokepoint Search Test to simulate real-time search for a target. Performance on this test was poor (39% accuracy) and showed moderate associations with tests of face matching and memory. In addition, trial-level confidence predicted accuracy, and for those participants who were previously familiar with one or more targets, higher familiarity was associated with increased accuracy. In Experiment 2, we found improvements in performance on the test when three recent images of the target, but not three social media images, were displayed during searches. Taken together, our results highlight the difficulties inherent in real-time searching for faces, with important implications for those security personnel who carry out this task on a daily basis.     

Unfamiliar face matching: Pairs out‐perform individuals and provide a route to training

Matching unfamiliar faces is known to be difficult. Here, we ask whether performance can be improved by asking viewers to work in pairs, a manipulation known to increase accuracy for low‐level visual discrimination tasks. Across four experiments we consistently find that face matching accuracy is higher for pairs of viewers than for individuals. This ‘pairs advantage’ is generally driven by adopting the response of the higher scoring partner. However, when the task becomes difficult, both partners' performance is improved by working in a pair. In two experiments, we find evidence that working in a pair can lead to subsequent improvements in individual performance, specifically for viewers whose accuracy is initially low. The pairs' technique therefore offers the opportunity for substantial improvements in face matching performance, along with an added training benefit.     

Human–Computer Interaction in Face Matching

Automatic facial recognition is becoming increasingly ubiquitous in security contexts such as passport control. Currently, Automated Border Crossing (ABC) systems in the United Kingdom (UK) and the European Union (EU) require supervision from a human operator who validates correct identity judgments and overrules incorrect decisions. As the accuracy of this human–computer interaction remains unknown, this research investigated how human validation is impacted by a priori face‐matching decisions such as those made by automated face recognition software. Observers matched pairs of faces that were already labeled onscreen as depicting the same identity or two different identities. The majority of these labels provided information that was consistent with the stimuli presented, but some were also inconsistent or provided “unresolved” information. Across three experiments, accuracy consistently deteriorated on trials that were inconsistently labeled, indicating that observers’ face‐matching decisions are biased by external information such as that provided by ABCs.     

Face processing and familiarity: Evidence from eye‐movement data

How is information extracted from familiar and unfamiliar faces? Three experiments, in which eye‐movement measures were used, examined whether there was differential sampling of the internal face region according to familiarity. Experiment 1 used a face familiarity task and found that whilst the majority of fixations fell within the internal region, there were no differences in the sampling of this region according to familiarity. Experiment 2 replicated these findings, using a standard recognition memory paradigm. The third experiment employed a matching task, and once again found that the majority of fixations fell within the internal region. Additionally, this experiment found that there was more sampling of the internal region when faces were familiar compared with when they were unfamiliar. The use of eye fixation measures affirms the importance of internal facial features in the recognition of familiar faces compared with unfamiliar faces, but only when viewers compare pairs of faces.     

Recognizing famous people

In daily life, face identification requires that the observer select a single representation from hundreds if not thousands in memory. This breadth of choice is nearly impossible to replicate in the laboratory using newly learned faces, especially in the context of a Bubbles experiment (Gosselin & Schyns, 2001). In this study, we obviated this concern by studying the performance of observers in a face-naming task using 210 faces of celebrities. On each trial, we presented a face randomly sampled with Bubbles. We performed least-square multiple linear regressions on the location of the samples and on accuracy to pinpoint the facial features that were used effectively in this task. Correct face identification relied primarily on the eye areas in spatial frequency bands ranging from 4.37 to 70 cycles per face (cpf) and on the mouth and the nose in a spatial frequency band ranging from 8.75 to 17.5 cpf. A comparison with other studies (Caldara et al., 2005; Schyns, Bonnar, & Gosselin, 2002) in which Bubbles was used with a set of 10 newly learned faces revealed that although the eye areas were useful across studies, the mouth area and higher spatial frequencies gained in importance when few newly learned faces were used.     

Dominance of texture over shape in facial identity processing is modulated by individual abilities

For face recognition, observers utilize both shape and texture information. Here, we investigated the relative diagnosticity of shape and texture for delayed matching of familiar and unfamiliar faces (Experiment 1) and identifying familiar and newly learned faces (Experiment 2). Within each familiarity condition, pairs of 3D‐captured faces were morphed selectively in either shape or texture in 20% steps, holding the respective other dimension constant. We also assessed participants’ individual face‐processing skills via the Bielefelder Famous Faces Test (BFFT), the Glasgow Face Matching Test, and the Cambridge Face Memory Test (CFMT). Using multilevel model analyses, we examined probabilities of same versus different responses (Experiment 1) and of original identity versus other/unknown identity responses (Experiment 2). Overall, texture was more diagnostic than shape for both delayed matching and identification, particularly so for familiar faces. On top of these overall effects, above‐average BFFT performance was associated with enhanced utilization of texture in both experiments. Furthermore, above‐average CFMT performance coincided with slightly reduced texture dominance in the delayed matching task (Experiment 1) and stronger sensitivity to morph‐based changes overall, that is irrespective of morph type, in the face identification task (Experiment 2). Our findings (1) show the disproportionate importance of texture information for processing familiar face identity and (2) provide further evidence that familiar and unfamiliar face identity perception are mediated by different underlying processes.     

Social exclusion influences attentional bias to social information

Using three experiments, the present study investigates the impact of social exclusion on attention. Specifically, we investigate whether social exclusion promotes attentional bias to social acceptance cues (smiling faces) or social exclusion cues (angry faces) among an Asian population. The Cyberball game was adopted to manipulate social inclusion or exclusion, and a dot‐probe task was used to measure individuals' responses to smiling or angry faces. In Experiments 1 and 2, each trial consisted of either a smiling or angry face that was paired with a neutral face. In Experiment 1, when the stimulus onset‐asynchronies (SOA) were 500 ms, the inhibition of return emerged, indirectly indicating that social exclusion promotes sensitivity to social acceptance cues. In Experiment 2, after setting the SOA to 200 ms, we found that social exclusion promotes attentional bias to smiling faces compared to neutral faces. In Experiment 3, both smiling and angry faces were shown during each trial, and we found that social exclusion promotes attentional bias to smiling faces compared to angry faces. Therefore, the present study extends our understanding of the relationship between social exclusion and attention. Overall, it appears that after social exclusion, the desire for social reconnection trumps the desire to avoid social exclusion.     

自动情绪调节对负性情绪面孔注意偏向的影响

本研究通过成语匹配任务启动情绪调节目标,在情绪flanker任务中考察了自动情绪调节启动对注意偏向的影响。结果表明,中性启动条件下,被试表现出对负性情绪面孔的注意偏向,而情绪调节启动条件下,被试对正性、负性情绪面孔的注意分配不存在显著差异。这一结果说明自动情绪调节可以有效地减弱被试的负性情绪面孔注意偏向。     

Perceptual biases in processing facial identity and emotion

Normal observers demonstrate a bias to process the left sides of faces during perceptual judgments about identity or emotion. This effect suggests a right cerebral hemisphere processing bias. To test the role of the right hemisphere and the involvement of configural processing underlying this effect, young and older control observers and patients with right hemisphere damage completed two chimeric faces tasks (emotion judgment and face identity matching) with both upright and inverted faces. For control observers, the emotion judgment task elicited a strong left-sided perceptual bias that was reduced in young controls and eliminated in older controls by face inversion. Right hemisphere damage reversed the bias, suggesting the right hemisphere was dominant for this task, but that the left hemisphere could be flexibly recruited when right hemisphere mechanisms are not available or dominant. In contrast, face identity judgments were associated most clearly with a vertical bias favouring the uppermost stimuli that was eliminated by face inversion and right hemisphere lesions. The results suggest these tasks involve different neurocognitive mechanisms. The role of the right hemisphere and ventral cortical stream involvement with configural processes in face processing is discussed.     

The basis of the 3/4 view advantage in face recognition

Three-quarter views of faces promote better recognition memory for previously unfamiliar faces than do full-face views. This paper reports experiments which examine the possible basis of the effect, and, in particular, examine whether the effect reflects some ‘canonical’ role for the 3/4 view of a face. Experiment 1 showed no advantage of 3/4 views over full-face views when the task was to decide whether or not each of a series of faces was that of a highly familiar colleague. In Experiment 2 a sequential matching task was used, where subjects had to respond positively if both members of a pair of faces were of the same person. When the faces used were highly familiar to the subjects, there was no evidence of an advantage for a 3/4 view in the matching task. Three-quarter views and full-face views led to equivalent performance, though profiles produced decrements in performance. When the same faces were shown to subjects who were unfamiliar with the faces, 3/4 views did lead to increased speeds in same trials, compared with full-face, though profiles again proved difficult. Thus a 3/4 view advantage appeared only where the faces were unfamiliar, and the task had to be performed at the level of visual matching. It appears that the 3/4 view advantage may be obtained only when the task involves explicit matching between test views and remembered target photographs, rather than reflecting any more fundamental properties of the representations used to recognize highly familiar faces.     

ERP evidence for task modulations on face perceptual processing at different spatial scales

Does the perceptual processing of faces flexibly adapt to the requirements of the categorization task at hand, or does it operate independently of this cognitive context? Behavioral studies have shown that the fine and coarse spatial scales of a face are differentially processed depending on the categorization task performed, thus suggesting that the latter can influence stimulus perception. Here, we investigated the time course of these task influences on perceptual processing by examining the visual N170 face‐sensitive Event‐Related Potential (ERP), while observers categorized faces for their gender and familiarity. Stimuli were full spectrum, or filtered versions that preserved either coarse or fine scale information of the faces. Behavioral results replicated previous findings of a differential processing of coarse and fine spatial scales across tasks. In addition, the N170 amplitude was larger in the Gender task as compared to the Familiarity task for LSF faces exclusively, thus showing that task demands differentially modulated the spatial scale processing on faces. These results suggest that the diagnosticity of scale‐specific cues in categorization tasks can modulate face processing.     

On the dominance of unidimensional rules in unsupervised categorization

In several experiments, observers tried to categorize stimuli constructed from two separable stimulus dimensions in the absence of any trial-by-trial feedback. In all of the experiments, the observers were told the number of categories (i.e., two), they were told that perfect accuracy was possible, and they were given extensive experience in the task (i.e., 800 trials). When the boundary separating the contrasting categories was umdimensional, the accuracy of all observers improved significantly over blocks (i.e., learning occurred), and all observers eventually responded optimally. When the optimal boundary was diagonal, none of the observers responded optimally. Instead they all used some sort of suboptimal unidimensional rule. In a separate feedback experiment, all observers responded optimally in the diagonal condition. These results contrast with those for supervised category learning; they support the hypothesis that in the absence of feedback, people are constrained to use unidimensional rules.     

Order of feature recognition in familiar and unfamiliar faces

Three experiments measured order of processing for single faces presented to the left or right visual field (VF) using a same-different matching task. In contrast to earlier studies, the stimuli in the present experiments were carefully matched for overall similarity prior to the actual experiments. Experiments 1 and 2 showed that a significant top-to-bottom order of processing occurred for line drawings of unfamiliar faces but not for line drawings of familiar faces. Experiment 3 found evidence supporting top-to-bottom processing for unfamiliar photographic face stimuli. The photographic stimuli in Experiment 3 were matched more quickly when presented in the left VF (right hemisphere); however, this VF asymmetry was not related to previously reported differences in order of processing. It is suggested that under some conditions faces presented to the right hemisphere may be processed more like familiar faces than faces presented to the left hemisphere; however, this difference is not critical for the left VF (right hemisphere) superiority often found in face recognition tasks.