The role of symmetry in attraction to average faces

Although many studies have demonstrated that average faces tend to be attractive, few studies have examined the extent to which symmetry contributes to the attractiveness of average faces. Such studies are potentially important, however, because average faces are highly symmetric and increasing the symmetry of face images increases their attractiveness. Here we demonstrate that increasing averageness of 2-D face shape independently of symmetry is sufficient to increase attractiveness, indicating that preferences for symmetry cannot solely explain the attractiveness of average faces. Additionally, we show that averageness preferences are significantly weaker when the effects of symmetry are controlled for using computer graphic methods than when the effects of symmetry are not controlled for, suggesting that symmetry contributes to the attractiveness of average faces. Importantly, this latter finding was not explained by the greater perceived similarity between versions offaces that varied in averageness, but not symmetry, than between versions of faces that varied in both averageness and symmetry.     

The contribution of external and internal features to the matching of unfamiliar faces

The relative efficacy of external and internal features in matching unfamiliar faces was studied in three experiments in which the subjects matched target and test faces differing in terms of external or internal features, or both. In Experiment 1 only full congruency between target and test faces was considered a match; in Experiments 2 and 3 faces sharing the same external and internal features were also considered to be matches. A total of 100 subjects matched 192 pairs of target and test faces in a same-different task. Reaction times and matching errors were recorded for analyses of variance. In all three experiments performance was best when either all features matched or all features mismatched, with mismatches having a slight edge. When matches of external and internal features with the target faces were inconsistent with each other, mismatches of external features led to faster responses in Experiments 1 and 2, and mismatches of internal features led to faster responses in Experiment 3. The results suggest that since faces are configurational stimuli, face matching is influenced by the non-relevant set of features; and that mismatches, especially of external features, influence face matching more than matches do.     

The contribution of morphology to word recognition

Summary Evidence of morphological processing was investigated in three word recognition tasks. In the first study, phonological ambiguity of the base morpheme in morphologically complex words of Serbo-Croatian was exploited in order to evaluate the claim that the base morpheme serves as the unit by which entries in the lexicon are accessed. An interaction of base morpheme ambiguity and affix characteristics was obtained and this outcome was interpreted as evidence that all morphological constituents of a word participate in lexical access. In the second study, facilitation due to morphological relatedness of prime and target was observed with Serbo-Croatian materials in the lexical decision and naming versions of the repetition priming task and results were interpreted as evidence of a morphological principle of organization among wholeword forms in the lexicon. In the third study, morphological affixes of both English and Serbo-Croatian words were segmented from a source word and affixed to a target word more rapidly than phonemically matched controls. Results suggest that the morphological constituents of complex words are available in some word recognition tasks and that morphological knowledge is represented in the speaker's lexicon.     

The role of motion and speech in face recognition at birth

Newborns, a few hours after birth, already encounter many different faces, talking or silently moving. How do they process these faces and which cues are important in early face recognition? In a series of six experiments, newborns were familiarized with an unfamiliar face in different contexts (photographs, talking, silently moving, and with only external movements of the head with speech sound). At test, they saw the familiar and a new faces either in photographs, silently moving, or talking. A novelty preference was evidenced at test when photographs were presented in the two phases. This result supports those already evidenced in several studies. A familiarity preference appeared only when the face was seen talking in the familiarization phase and in a photograph or talking again at test. This suggests that the simultaneous presence of speech sound, and rigid and nonrigid movements present in a talking face enhances recognition of interactive faces at birth.     

Discriminative infant smiling to orientations of talking faces of mother and stranger.

Thirty-two infants aged 14 and 20 weeks were presented with a live face in each of eight conditions, which consisted of all combinations of (a) a 0° or 90° orientation; (b) familiar face (the infant's mother) or distinctively unfamiliar face; and (c) talking or silent context. The previous findings that younger infants smile longer at 0° than at 90° faces and that this differential responsiveness to orientation wanes with increasing age were replicated; the hypothesis that older infants would smile longest at their mothers' talking faces in the 0° orientation was confirmed. In addition, infants of both ages smiled more at their mothers than at the stranger, although this effect interacted with orientation and sex of the infant.     

The role of motion in learning new faces

Four experiments are reported that investigate the usefulness of rigid (head nodding, shaking) and nonrigid (talking, expressions) motion for establishing new face representations of previously unfamiliar faces. Results show that viewing a face in motion leads to more accurate face learning, compared with viewing a single static image (Experiment 1). The advantage for viewing the face moving rigidly seems to be due to the different angles of view contained in these sequences (Experiment 2). However, the advantage for nonrigid motion is not simply due to multiple images (Experiment 3) and is not specifically linked to forwards motion but extends to reversed sequences (Experiment 4). Thus, although we have demonstrated beneficial effects of motion for face learning, they do not seem to be due to the specific dynamic properties of the sequences shown. Instead, the advantage for nonrigid motion may reflect increased attention to faces moving in a socially important manner.     

The speed of recognition of personally familiar faces

Despite the generally accepted notion that humans are very good and fast at recognising familiar individuals from their faces, the actual speed with which this fundamental brain function can be achieved remains largely unknown. Here, two groups of participants were required to respond by finger-lift when presented with either a photograph of a personally familiar face (classmate), or an unfamiliar one. This speeded manual go/no-go categorisation task revealed that personally familiar faces could be categorised as early as 380 ms after presentation, about 80 ms faster than unfamiliar faces. When response times were averaged across all 8 stimulus presentations, we found that minimum RTs for both familiar and unfamiliar face decisions were substantially lower (310 ms and 370 ms). Analyses confirmed that stimulus repetition enhanced the speed with which faces were categorised, irrespective of familiarity, and that repetition did not affect the observed benefit in RTS for familiar over unfamiliar faces. These data, representing the elapsed time from stimulus onset to motor output, put constraints on the time course of familiar face recognition in the human brain, which can be tracked more precisely by high temporal resolution electrophysiological measures.     

The role of movement in the recognition of famous faces

The effects of movement on the recognition of famous faces shown in difficult conditions were investigated. Images were presented as negatives, upside down (inverted), and thresholded. Results indicate that, under all these conditions, moving faces were recognized significantly better than static ones. One possible explanation of this effect could be that a moving sequence contains more static information about the different views and expressions of the face than does a single static image. However, even when the amount of static information was equated (Experiments 3 and 4), there was still an advantage for moving sequences that contained their original dynamic properties. The results suggest that the dynamics of the motion provide additional information, helping to access an established familiar face representation. Both the theoretical and the practical implications for these findings are discussed.     

The social-encoding benefit in face recognition is generalized to other-race faces

Faces are visual stimuli that convey rich social information. Previous experiments found better recognition for faces that were evaluated based on their social traits than on their perceptual features during encoding. Here, we ask whether this social-encoding benefit in face recognition is also found for categories of faces that we have no previous social experience with, such as other-race faces. To answer this question, we first explored whether social and perceptual evaluations for other-race faces are consistent and valid. We then asked whether social evaluations during encoding improve recognition for other-race faces. Results show that social and perceptual evaluations of own- and other-race faces were valid. We also found high agreement in social and perceptual evaluations across individuals from different races. This indicates that evaluations of other-race faces are not random but meaningful. Furthermore, we found that social evaluations facilitated face recognition regardless of race, demonstrating a social-encoding benefit for both own- and other-race faces. Our findings highlight the role of social information in face recognition and show how it can be used to improve recognition of categories of faces that are hard to recognize due to lack of experience with them.     

Viewpoint-dependent recognition of familiar faces

The question whether object representations in the human brain are object-centered or viewer-centered has motivated a variety of experiments with divergent results. A key issue concerns the visual recognition of objects seen from novel views. If recognition performance depends on whether a particular view has been seen before, it can be interpreted as evidence for a viewer-centered representation. Earlier experiments used unfamiliar objects to provide the experimenter with complete control over the observer's previous experience with the object. In this study, we tested whether human recognition shows viewpoint dependence for the highly familiar faces of well-known colleagues and for the observer's own face. We found that observers are poorer at recognizing their own profile, whereas there is no difference in response time between frontal and profile views of other faces. This result shows that extensive experience and familiarity with one's own face is not sufficient to produce viewpoint invariance. Our result provides strong evidence for viewer-centered representations in human visual recognition even for highly familiar objects.     

The effect of motion at encoding and retrieval for same- and other-race face recognition

In an experimental study, we assessed the role of motion when encoding and recognizing unfamiliar faces, using an old/new recognition memory paradigm. Our findings revealed a clear advantage for learning unfamiliar faces moving non-rigidly, compared with static faces. This advantage for motion was found with both same- and other-race faces. Furthermore, results indicate that it is more important that the face is learnt in motion than recognized from a moving clip. Interestingly, despite a reliable other-race effect being revealed, participants were able to utilize motion information exhibited by other-race faces in a manner akin to the motion advantage found for same-race faces. The implications of these findings are discussed in relation to the nature of the stored face representations, considering whether the facilitative role found here can be explained by factors other than motion per se.     

Expression influences the recognition of familiar faces

Face recognition has been assumed to be independent of facial expression. We used familiar and unfamiliar faces that were morphed from a happy to an angry expression within a given identity. Participants performed speeded two-choice decisions according to whether or not a face was familiar. Consistent with earlier findings, reaction times for classifications of unfamiliar faces were independent of facial expressions. In contrast, expression clearly influenced the recognition of familiar faces. with fastest recognition for moderately happy expressions. This suggests that representations of familiar faces for recognition preserve some information about typical emotional expressions.     

The contribution of head motion cues to localization of low-pass noise

Localization of low-pass sounds was tested in relation to aspects of Wallach’s (1939, 1940) hypotheses about the role of head movement in front/back and elevation discrimination. With a 3-sec signal, free movement of the head offered only small advantage over a single rotation through 45° for detecting elevation differences. Very slight rotation, as observed using a 0.5-sec signal, seemed sufficient to prevent front/back confusion. Cluster analysis showed that, in detecting elevation, some listeners benefited from rotation, some benefited from natural movement, and some from both. Evidence was found indicating that a moving auditory system generates information for the whereabouts of sounds, even when the movement does not result in the listener facing the source. Results offer significant if partial support for Wallach’s hypotheses.     

The role of dynamic information in the recognition of unfamiliar faces

The effects of movement on unfamiliar face recognition were investigated. In an incidental learning task, faces were studied either as computer-animated (moving) displays or as a series of static images, with identical numbers of frames shown for each. The movements were either nonrigid transformations (changes in expression) or rigid rotations in depth (nodding or shaking). At test, participants saw either single, static images or moving sequences. Only one experiment showed a significant effect of study type, in favor of static instances. There was no additional advantage from studying faces in motion in these experiments, in which both study types showed the same amounts of information. Recognition memory was relatively unaffected by changes in expression between study and test. Effects of viewpoint change were large when expressive transformations had been studied but much smaller when rigid rotations in depth had been studied. The series of experiments did reveal a slight advantage for testing memory with moving compared with static faces, consistent with recent findings using familiar faces. Future work will need to examine whether such effects may also be due to the additional information provided by an animated sequence.     

Eye-tracking the own-gender bias in face recognition: Other-gender faces are viewed differently to own-gender faces

Research on the own-gender bias in face recognition has indicated an asymmetrical effect: an effect found only in women. We investigated the own-gender bias, using an eye-tracker to examine whether the own-gender bias is associated with differential processing strategies. We found an own-gender bias in our female participants. Our eye-tracking analysis indicated different scanning behaviours when processing own- and other-gender faces, with longer and more fixations to the eyes when viewing own-gender faces. Our results favour the socio-cognitive model, whilst acknowledging the role of perceptual expertise in the own-gender bias.     

Famous faces as icons. The illusion of being an expert in the recognition of famous faces

It is a common belief that we are experts in the processing of famous faces. Although our ability to quickly and accurately recognise pictures of famous faces is quite impressive, we might not really process famous faces as faces per se, but as 'icons' or famous still pictures of famous faces. This assumption was tested in two parallel experiments employing a recognition task on famous, but personally unfamiliar, and on personally familiar faces. Both tests included (a) original, 'iconic' pictures, (b) slightly modified versions of familiar pictures, and (c) rather unfamiliar pictures of familiar persons. Participants (n = 70 + 70) indeed recognised original pictures of famous and personally familiar people very accurately, while performing poorly in recognising slightly modified, as well as unfamiliar versions of famous, but not personally familiar persons. These results indicate that the successful processing of famous faces may depend on icons imbued in society but not on the face as such.     

On the contribution of perceptual fluency and priming to recognition memory

Repetition priming has been shown to be independent of recognition memory. Thus, the severely amnesic patient E.P. has demonstrated intact stem completion priming and perceptual identification priming, despite at-chance performance on recognition memory tasks. It has also been shown that perceptual fluency can influence feelings of familiarity, in the sense that items perceived more quickly tend to be identified as familiar. If studied items are identified more fluently, due to perceptual priming, and fluency leads to familiarity, why do severely amnesic patients perform no better than chance on recognition memory tasks? One possibility is that severely amnesic patients do not exhibit normal fluency. Another possibility is that fluency is not a sufficiently strong cue for familiarity. In two experiments, 2 severely amnesic patients, 3 moderately amnesic patients, and 8 controls saw words slowly clearing from a mask. The participants identified each word as quickly as possible and then made a recognition (old/new) judgment. All the participants exhibited fluency, in that old responses were associated with shorter identification times than new responses were. In addition, for the severely amnesic patients, priming was intact, and recognition memory performance was at chance. We next calculated how much priming and fluency should elevate the probability of accurate recognition. The tendency to identify studied words rapidly (.6) and the tendency to label these rapidly identified words old (.6) would result in 36% of the studied words being labeled old. Other studied words were identified slowly (.4) but were still labeled old (.4), resulting in an additional 16% of studied words labeled old. Thus, the presence of fluency increases the probability of accurate recognition judgments to only 52% (chance = 50%). This finding explains why amnesic patients can exhibit both priming and fluency yet still perform at chance on recognition tests.