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.     

Demonstrating how unfamiliar faces become familiar using a face matching task

Two experiments examine a novel method of assessing face familiarity that does not require explicit identification of presented faces. Earlier research (Clutterbuck & Johnston, 2002; Young, Hay, McWeeny, Flude, & Ellis, 1985) has shown that different views of the same face can be matched more quickly for familiar than for unfamiliar faces. This study examines whether exposure to previously novel faces allows the speed with which they can be matched to be increased, thus allowing a means of assessing how faces become familiar. In Experiment 1, participants viewed two sets of unfamiliar faces presented for either many, short intervals or for few, long intervals. At test, previously familiar (famous) faces were matched more quickly than novel faces or learned faces. In addition, learned faces seen on many, brief occasions were matched more quickly than the novel faces or faces seen on fewer, longer occasions. However, this was only observed when participants performed “different” decision matches. In Experiment 2, the similarity between face pairs was controlled more strictly. Once again, matches were performed on familiar faces more quickly than on unfamiliar or learned items. However, matches made to learned faces were significantly faster than those made to completely novel faces. This was now observed for both same and different match decisions. The use of this matching task as a means of tracking how unfamiliar faces become familiar is discussed.     

The relative importance of external and internal features of facial composites

Three experiments are reported that compare the quality of external with internal regions within a set of facial composites using two matching‐type tasks. Composites are constructed with the aim of triggering recognition from people familiar with the targets, and past research suggests internal face features dominate representations of familiar faces in memory. However the experiments reported here show that the internal regions of composites are very poorly matched against the faces they purport to represent, while external feature regions alone were matched almost as well as complete composites. In Experiments 1 and 2 the composites used were constructed by participant‐witnesses who were unfamiliar with the targets and therefore were predicted to demonstrate a bias towards the external parts of a face. In Experiment 3 we compared witnesses who were familiar or unfamiliar with the target items, but for both groups the external features were much better reproduced in the composites, suggesting it is the process of composite construction itself which is responsible for the poverty of the internal features. Practical implications of these results are discussed.     

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.     

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.     

Age differences in memory span

Five-year-olds recalled fewer items than adults in memory-span tasks involving both familiar and unfamiliar faces. This occurred even though the use of rehearsal and recoding strategies was minimized for adults. This residual age difference may be partially accounted for by two further processing limitations in children. The five-year-olds needed more time than adults to name a face (Experiment 1) and to encode a face (Experiment 2). In order to test whether limitations in children's initial recognition and stimulus-identification processes could account for recall performance, Experiment 3 reduced adults' exposure duration in the memory-span task. This led to a drastic reduction in the age difference. Other factors contributing to remaining age differences included adults' adaptability in using various alternative encoding and retrieval strategies which elevated their recall performance.     

It's not what you say but the way you say it: matching faces and voices

Recent studies have shown that the face and voice of an unfamiliar person can be matched for identity. Here the authors compare the relative effects of changing sentence content (what is said) and sentence manner (how it is said) on matching identity between faces and voices. A change between speaking a sentence as a statement and as a question disrupted matching performance, whereas changing the sentence itself did not. This was the case when the faces and voices were from the same race as participants and speaking a familiar language (English; Experiment 1) or from another race and speaking an unfamiliar language (Japanese; Experiment 2). Altering manner between conversational and clear speech (Experiment 3) or between conversational and casual speech (Experiment 4) was also disruptive. However, artificially slowing (Experiment 5) or speeding (Experiment 6) speech did not affect cross-modal matching performance. The results show that bimodal cues to identity are closely linked to manner but that content (what is said) and absolute tempo are not critical. Instead, prosodic variations in rhythmic structure and/or expressiveness may provide a bimodal, dynamic identity signature.     

Effects of geometric distortions,Gaussian blur,and contrast negation on recognition of familiar faces

It is assumed that “configural processing” is important for recognizing people whom we know. Studies have shown better discrimination of relational changes between facial features when faces are presented upright than upside down and when presented as photographic negatives. However, studies have also demonstrated tolerance for complex changes to facial configuration of familiar faces when images are geometrically distorted. In two experiments, we explored effects of linear stretching, Gaussian blur, and contrast negation on recognition of familiar or unfamiliar faces (Experiment 1) and familiar or unfamiliar company brand logos (Experiment 2). Only contrast negation severely impaired recognition of familiar faces but not unfamiliar faces or company brand logos. Effects of contrast negation were additional to linear stretching, whereas linear stretching independently had no impact on recognition. These findings highlight an important deficit in the recognition of familiar faces caused by contrast negation.     

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.     

Can active navigation be as good as driving? A comparison of spatial memory in drivers and backseat drivers

When driving a vehicle, either the driver or a passenger (henceforth: backseat driver) may be responsible for navigation. Research on active navigation, primarily addressed in virtual environments, suggests that controlling navigation is more central for spatial learning than controlling movement. To test this assumption in a real-world scenario, we manipulated movement control through seating participants in the front or the back position of a tandem bike, and navigation control by presenting differently detailed maps to participants unfamiliar (Experiment 1) or familiar (Experiment 2) with an environment. Landmark knowledge was tested with recognition tasks. For participants unfamiliar with the environment (Experiment 1), passive navigation enabled better landmark recognition than active navigation, but there was no effect of movement control. For participants more familiar with the environment (Experiment 2), there was no effect of navigation control, but drivers showed better landmark recognition than backseat drivers. These findings are discussed in relation to action memory research. Measures of route and survey knowledge demonstrated that good performance resulted from active navigation (Experiment 1-2). Moreover, with regard to these measures, driving compensated for passive navigation if the environment was familiar (Experiment 2). An additional experiment in a lab setting (Experiment 3) validated the manipulation of navigation control and the used tasks and demonstrated the importance of real environment exposure. As our findings suggest, driving may be more relevant for remembering landmarks, but actively controlling navigation (even as a backseat driver) is more relevant for remembering a route than maneuvering a vehicle.     

Improving Discrimination and Face Matching with Caricature

Identification of faces from photographs is a common security measure, but matching unfamiliar faces produces high rates of error. Caricatures of familiar people are highly identifiable because they exaggerate distinctive features. We investigated whether exaggerating unfamiliar faces through caricaturing could also improve face‐matching accuracy. In Experiment 1, face‐matching arrays were caricatured relative to an average by 30%, 50% and 70%. Correct rejection of the target‐absent arrays was improved at all levels. Accurate matches increased at 30%, but at 70%, the transformation was too extreme, and all of the arrays were more likely to be rejected. In Experiment 2, photographic identification (ID) images were caricatured by 30% and 50% and matched to life‐size photographs. Rejection of foils improved, but the ID of matching images was impaired. Modest levels of caricature may improve discrimination in unfamiliar face matching, but at stronger levels, a conservative response bias may inhibit accurate ID. Copyright © 2013 John Wiley & Sons, Ltd.     

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.     

The emotional impact of faces (but not names): Face specific changes in skin conductance responses to familiar and unfamiliar people

Skin Conductance Responses (SCRs) to familiar and unfamiliar names and faces were recorded from independent groups of subjects, using two different presentation designs: the first employing fewer familiar than unfamiliar items (Tranel, Fowles, and Damasio, 1985) and the second employing equal numbers of familiar and unfamiliar items. In both designs, familiar faces were responded to significantly more strongly than unfamiliar faces, whereas for names there was no difference in responses to familiar and unfamiliar stimuli. Faces produced significantly larger overall SCRs than names in the unequal familiar/unfamiliar ratio design, but this effect was not observed in the equal ratio design. The results are discussed with particular reference to those previously published by Tranel et al. (1985) and in relation to work both on covert recognition in prosopagnosia and on one of the delusional misidentification syndromes known as the Capgras delusion. This study was carried out with generous support from the EJLB Foundation (Canada) and the Wellcome Trust.     

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.     

The emotional impact of faces (but not names): Face specific changes in skin conductance responses to familiar and unfamiliar people

Skin Conductance Responses (SCRs) to familiar and unfamiliar names and faces were recorded from independent groups of subjects, using two different presentation designs: the first employing fewer familiar than unfamiliar items (Tranel, Fowles, and Damasio, 1985) and the second employing equal numbers of familiar and unfamiliar items. In both designs, familiar faces were responded to significantly more strongly than unfamiliar faces, whereas for names there was no difference in responses to familiar and unfamiliar stimuli. Faces produced significantly larger overall SCRs than names in the unequal familiar/unfamiliar ratio design, but this effect was not observed in the equal ratio design. The results are discussed with particular reference to those previously published by Tranel et al. (1985) and in relation to work both on covert recognition in prosopagnosia and on one of the delusional misidentification syndromes known as the Capgras delusion. This study was carried out with generous support from the EJLB Foundation (Canada) and the Wellcome Trust.     

Perceptual asymmetries are preserved in memory for highly familiar faces of self and friend

We investigated the effect of familiarity on people's perception of facial likeness by asking participants to choose which of two mirror-symmetric chimeric images (made from the left or right half of a photograph of a face) looked more like an original image. In separate trials the participants made this judgment for their own face and for the face of a close friend; half of them matched to a true image of the original and half matched to a mirror image of the original. In the case of matching to a friend's face presented in the familiar orientation, over 80% of participants chose the left-left composite to be a better likeness to the original, whereas only 62% showed the same left-side bias when matching to a mirror image. The difference is significant, and the result contrasts markedly with a second experiment where participants who were unfamiliar with the faces showed comparable left-side biases when matching to true or mirror reversed images. The result suggests that perceptual asymmetries are retained in our long-term memory for highly familiar faces. While matching to images of self also showed an effect of familiarity, the data in this condition show less evidence of perceptual asymmetry and are discussed in relation to recent research on the representation of one's own face.     

The effect of familiarity on face adaptation

Face aftereffects can provide information on how faces are stored by the human visual system (eg Leopold et al, 2001 Nature Neuroscience 4 89-94), but few studies have used robustly represented (highly familiar) faces. In this study we investigated the influence of facial familiarity on adaptation effects. Participants were adapted to a series of distorted faces (their own face, a famous face, or an unfamiliar face). In experiment 1, figural aftereffects were significantly smaller when participants were adapted to their own face than when they were adapted to the other faces (ie their own face appeared significantly less distorted than a famous or unfamiliar face). Experiment 2 showed that this 'own-face' effect did not occur when the same faces were used as adaptation stimuli for participants who were unfamiliar with them. Experiment 3 replicated experiment 1, but included a pre-adaptation baseline. The results highlight the importance of considering facial familiarity when conducting research on face aftereffects.     

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.     

Exploring levels of face familiarity by using an indirect face-matching measure

An experiment is reported in which participants matched complete images of unfamiliar, moderately familiar, and highly familiar faces with simultaneously presented images of internal and external features. Participants had to decide if the two images depicted same or different individuals. Matches to internal features were made faster to highly familiar faces than both to moderately familiar and to unfamiliar faces, and matches to moderately familiar faces were made faster than to unfamiliar faces. For external feature matches, this advantage was only found for "different" decision matches to highly familiar faces compared to unfamiliar faces. The results indicate that the differences in familiar and unfamiliar face processing are not the result of all-or-none effects, but seem to have a graded impact on matching performance. These findings extend the earlier work of Young et al (1985 Perception 14 737-746), and we discuss the possibility of using the matching task as an indirect measure of face familiarity.     

Internal feature saliency as a marker of familiarity and configural processing

Two experiments that explore the internal feature advantage (IFA) in familiar face processing are reported. The IFA involves more efficient processing of internal features for familiar faces over unfamiliar ones. Experiment 1 examined the possibility of a configural basis for this effect through use of a matching task for familiar and unfamiliar faces presented both upright and upside-down. Results revealed the predicted IFA for familiar faces when stimuli were upright, but this was removed when stimuli were inverted. Experiment 2 examined the degree of training required before the IFA was demonstrated. Latency results revealed that whilst 90–180 s of exposure was sufficient to generate an IFA of intermediate magnitude, 180–270 s of exposure was required before the IFA was equivalent to that demonstrated for a familiar face. Taken together, these results offer three conclusions: First, the IFA is reaffirmed as an objective indicator of familiarity; second, the IFA is seen to rest on configural processing; and finally, the development of the IFA with familiarity indicates a development of configural processing with familiarity. As such, insight is gained as to the type of processing changes that occur as familiarity is gradually acquired.