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Isolating the special component of face recognition: peripheral identification and a Mooney face.

A previous finding argues that, for faces, configural (holistic) processing can operate even in the complete absence of part-based contributions to recognition. Here, this result is confirmed using 2 methods. In both, recognition of inverted faces (parts only) was removed altogether (chance identification of faces in the periphery; no perception of a particularly hard-to-see Mooney face). Recognition of upright faces (configural plus parts), however, remained good. The simplicity of these new "isolation" techniques makes them ideal for (a) assessing configural processing in specialist populations (e.g., children, object experts) and (b) exploring properties of configural processing for faces in detail. As an example of the latter, orientation tuning was tested. Results argue against models in which faces are rotated to upright prior to identification.

Cues↗

Recognising the ageing face: the role of age in face processing.

The effect of age-induced changes on face recognition were investigated as a means of exploring the role of age in the encoding of new facial memories. The ability of participants to recognise each of six previously learnt faces was tested with versions which were either identical to the learnt faces, the same age (but different in pose and expression), or younger or older in age. Participants were able to cope well with facial changes induced by ageing: their performance with older, but not younger, versions was comparable to that with faces which differed only in pose and expression. Since the large majority of different age versions were recognised successfully, it can be concluded that the process of recognition does not require an exact match in age characteristics between the stored representation of a face and the face currently in view. As the age-related changes explored here were those that occur during the period of growth, this in turn implies that the underlying structural physical properties of the face are (in addition to pose and facial expression) invariant to a certain extent.

Adolescent↗

Configural face processing develops more slowly than featural face processing.

Expertise in face processing takes many years to develop. To determine the contribution of different face-processing skills to this slow development, we altered a single face so as to create sets of faces designed to measure featural, configural, and contour processing. Within each set, faces differed only in the shape of the eyes and mouth (featural set), only in the spacing of the eyes and mouth (spacing set), or only in the shape of the external contour (contour set). We presented adults, and children aged 6, 8, and 10 years, with pairs of upright and inverted faces and instructed them to indicate whether the two faces were the same or different. Adults showed a larger inversion effect for the spacing set than for the featural and external contour sets, confirming that the spacing set taps configural processing. On the spacing set, all groups of children made more errors than adults. In contrast, on the external contour and featural sets, children at all ages were almost as accurate as adults, with no significant difference beginning at age 6 on the external contour set and beginning at age 10 on the featural set. Overall, the results indicate that adult expertise in configural processing is especially slow to develop.

Adolescent↗

Convolutional face finder: a neural architecture for fast and robust face detection.

In this paper, we present a novel face detection approach based on a convolutional neural architecture, designed to robustly detect highly variable face patterns, rotated up to +/-20 degrees in image plane and turned up to +/-60 degrees, in complex real world images. The proposed system automatically synthesizes simple problem-specific feature extractors from a training set of face and nonface patterns, without making any assumptions or using any hand-made design concerning the features to extract or the areas of the face pattern to analyze. The face detection procedure acts like a pipeline of simple convolution and subsampling modules that treat the raw input image as a whole. We therefore show that an efficient face detection system does not require any costly local preprocessing before classification of image areas. The proposed scheme provides very high detection rate with a particularly low level of false positives, demonstrated on difficult test sets, without requiring the use of multiple networks for handling difficult cases. We present extensive experimental results illustrating the efficiency of the proposed approach on difficult test sets and including an in-depth sensitivity analysis with respect to the degrees of variability of the face patterns.

Algorithms↗

Development of face processing: the effect of face inversion.

The present experiment examined the degree to which analytic and holistic modes of processing play a role in the way children and adults categorize upright and inverted faces. Seven-year-old children (n = 38), 10-year-old children (n = 40), and adults (n = 55) were instructed to classify upright and inverted faces into two categories. The construction of the categories allowed participants to categorize the faces either analytically (by focusing on a single attribute) or holistically (in terms of overall similarity). The results show both a developmental trend from analytic to holistic processing and an effect of face inversion with increasing age. Thus, it appears that 7-year-old children process upright and inverted faces in a way comparable to their processing of nonfacial visual stimuli, namely analytically, whereas a growing proportion of 10-year-olds and adults process only upright faces holistically by adopting a specific mode of face processing.

Adult↗

Expert face coding: configural and component coding of own-race and other-race faces.

Configural and holistic coding are hallmarks of face perception. Although recent studies have shown that own-race faces are coded more holistically than other-race faces, the evidence for better configural coding of own-race faces is equivocal. We directly measured configural and component coding of own- and other-race male faces in Caucasian and Chinese participants. We manipulated individual features (components) or their spatial relations (configurations) using a novel morphing method to vary difficulty parametrically and tested sensitivity to these changes in a sequential matching task. Both configural and component coding were better for upright own-race than for upright other-race faces. Inversion impaired detection of configural changes more than it did detection of component changes, but also impaired performance more for easier discriminations, independent of type of change. These results challenge explanations of face expertise that rely solely on configural and holistic processing, and also call into question the widespread interpretation of large inversion decrements as diagnostic of configural coding.

Adult↗

Sex differences in face recognition--women's faces make the difference.

Sex differences favoring women have been found in face recognition tasks as well as in verbal episodic memory tasks. Women's higher face recognition performance was hypothesized to be related to either their higher verbal ability or to their superiority in recognizing female faces, rather than faces in general. Results showed that whereas there were no differences between men and women in the recognition of male faces, or in verbal ability, women performed at a higher level than men in the recognition of female faces. Verbal ability did not influence women's face recognition performance. Potential explanations for this pattern of data, such as sex differences in interest and prior knowledge, are discussed.

Adult↗

Perceived eye size is larger in happy faces than in surprised faces.

We demonstrated that perceived eye size is affected by facial expression. Stimuli were composite photographs generated from happy, surprised, and neutral faces. The top halves of the original photographs were separated from the bottom halves by a horizontal line below the eyes, and were pasted onto the superior areas of the happy and the surprised faces. Thus, the composites were happy faces and surprised faces with happy eyes, neutral eyes, and surprised eyes. When the eyes of the happy and the surprised face composites with the same top halves were compared by 142 naïve observers, the happy face composites were judged to have larger eyes than the surprised face composites.

Emotions↗

Functional asymmetry in the human face: perception of health in the left and right sides of the face.

The expression of health on the human face, like beauty or emotions, is an important biological display. Previous findings of left-right functional asymmetry in facial attractiveness and the linkage of attractiveness and health in evolutionary biology notions have prompted the present study. A total of 38 pairs of left-left and right-right facial composites were viewed by 24 subjects on a computer screen, and the task was to decide which member of the pair looked healthier or there was no difference. The results revealed a significant interaction between face side and sex of face. Right-right composites of women's faces were judged significantly healthier than left-left, whereas in men's faces, no significant left-right difference emerged. As these results parallel previous findings of attractiveness in the identical set of faces, we propose that evolutionary biology notions linking the appearance of health and of attractiveness apply to the human face as well.

Journal Article↗

Right N170 modulation in a face discrimination task: an account for categorical perception of familiar faces.

Behavioral studies have shown that two different morphed faces belonging to the same identity are harder to discriminate than two faces stemming from two different identities. The temporal course of this categorical perception effect has been explored through event-related potentials. Three kinds of pairs were presented in a matching task: (1) two different morphed faces representing the same identity (within), (2) two other faces representing two different identities (between), and (3) two identical morphed faces (same). Following the second face onset in the pair, the amplitude of the right occipitotemporal negativity (N170) was reduced for within and same pairs as compared with between pairs, suggesting an identity priming effect. We also observed a modulation of the P3b wave, as the amplitude of the responses for within pairs was higher than for between and same pairs, suggesting a higher complexity of the task for within pairs. These results indicate that categorical perception of human faces has a perceptual origin in the right occipitotemporal hemisphere.

Adult↗

Cortical specialisation for face processing: face-sensitive event-related potential components in 3- and 12-month-old infants.

The adult N170 is considered to be an electrophysiological marker of specialised mechanisms for face processing, but little is known about its developmental origin. Previous work has identified two face-sensitive infant ERP components (N290 and P400) (J. Cog. Neurosci. 14 (2002), 199). In the present study, we assessed the specificity (to upright human faces) of these infant components at 3 and 12 months. At 12 months the degree of specificity observed in both components was similar to that seen in the adult N170. In contrast, at 3 months of age the N290 and P400 did not show the same level of specificity for human faces as that observed at 12 months. Our findings suggest that (1) both face-sensitive components increase in their specificity for upright human faces during development, and (2) the adult N170 is not preceded by a single developmental precursor, but rather emerges as a consequence of the integration of two functionally and morphologically distinct components (N290 and P400).

Animals↗

Glucose enhancement of face recognition is unaffected by alterations of face features.

Glucose improves memory on a variety of tasks has been well established in both the animal and human literature. Of particular relevance to the present experiment is the finding that administration of glucose improves face recognition performance in both healthy, young adults and in Alzheimer's patients. This experiment attempted to expand on these findings to determine if glucose-enhanced performance for face recognition is specific to certain face features (e.g., nose, eyes, or hair). In a between subjects experiment that tested healthy, young adults, a pre-training administration of glucose (50 g) was shown to improve face recognition performance relative to placebo (27.3mg saccharin); however, the significant improvement on the task was not specific to a particular feature. This result suggests that glucose did not enhance memory for individual face features, but rather enhanced overall memory for face stimuli.

Adolescent↗

The influence of face similarity in the case of the perception of morphed self-face.

The purpose of the study was to examine if differences in behavioral effects in terms of facial self-recognition, compared to other identity recognition (familiar, strange) exist. Morphed versions of three facial identities were used in the experiment. The subject's own face was morphed with an unknown identity. A face of a highly familar person and of a stranger were also morphed in the same manner. This morphing procedure was repeated six times for each identity, but with six different unknown faces, in which three of the unknown faces were rated as being similar and the other three as dissimilar. The reaction times and categorical boundaries were then measured. The major finding of the study was that there were significant delayed mean reaction times for the morphed images of version "self versus similarly rated unknown faces" in contrast to the images of "self versus dissimilarly rated unknown faces" only. No significant differences were found in any of the other morphed versions. The authors interpret this result as being uniquely associated to the facial self-recognition and suggest that this association might be related to the "self effect."

Adult↗

The role of familiarity in a face classification task using thatcherized faces.

Two experiments are reported to test the proposition that facial familiarity influences processing on a face classification task. Thatcherization was used to generate distorted versions of familiar and unfamiliar individuals. Using both a 2AFC (which is "odd"?) task to pairs of images (Experiment 1) and an "odd/normal" task to single images (Experiment 2), results were consistent and indicated that familiarity with the target face facilitated the face classification decision. These results accord with the proposal that familiarity influences the early visual processing of faces. Results are evaluated with respect to four theoretical developments of Valentine's (1991) face-space model, and can be accommodated with the two models that assume familiarity to be encoded within a region of face space.

Adolescent↗

When inverted faces are recognized: the role of configural information in face recognition.

The identification of upright faces seems to involve a special sensitivity to "configural" information, the processing of which is less effective when the face is inverted. However the precise meaning of "configural" remains unclear. Five experiments are presented, which showed that the disruption of the processing of relational, rather than holistic, information largely determines the occurrence as well as the size of the face-inversion effect. In Experiment 1, faces could be identified either by unique combinations of local information (e.g. a specific eye colour plus hair colour) or by unique relational information (e.g. nose-mouth distance). The former showed no inversion effect, whereas the latter did. A combination of local and relational information (Experiment 2) again produced an inversion effect, although this effect was smaller than that found when only relational information was used. The results were replicated in Experiment 3 when differences in the brightness of local features were used instead of specific colour combinations. Experiment 4 used different retrieval conditions to distinguish relational from holistic processing, and demonstrated again that spatial relations between single features appeared to provide crucial information for face recognition. In Experiment 5, the importance of relational information was confirmed using faces that also varied in the shapes of local features.

Adult↗

Are face-responsive regions selective only for faces?

To examine the specificity of face-responsive regions for face processing, we used fMRI to measure the response of the fusiform gyrus and the superior temporal sulcus (STS) to pictures of human faces, animals, faceless animals, and houses. Results indicate that faces, animals, and faceless animals all elicited greater activity than houses, and had identical peaks of activation in the lateral fusiform gyrus, bilaterally, and in the right posterior STS. Moreover, within the lateral fusiform gyrus the responses to faces, animals and faceless animals were all greater than the responses to these stimuli in the medial aspect of the fusiform gyrus, a region that responds more strongly to other objects (e.g. houses). These findings suggest that the neural representation of animals in the fusiform gyrus and the posterior STS relies strongly on the same neural substrates that represent faces.

Adult↗

An earlier component of face perception detected by seeing-as-face task.

To investigate the time sequence of the neural processes underlying face perception, magnetoencephalography was performed using a seeing-as-face task, in which visual inputs were identical across two conditions, but subject perceptions differed: one being a non-specific pattern of geographical shapes, the other being a percept of a face. Subtraction between the two conditions revealed a response occurring 120 ms after stimulus onset in right occipital, approximately 50 ms earlier than previously reported response at a latency of 170 ms at the right fusiform gyrus. As our novel task completely excluded differences in low-level properties of visual stimuli between control and face conditions, these two responses were considered specific to face perception. The result supported the two-stage theory of face processing.

Adult↗

Behavioural and neurophysiological evidence for face identity and face emotion processing in animals.

Visual cues from faces provide important social information relating to individual identity, sexual attraction and emotional state. Behavioural and neurophysiological studies on both monkeys and sheep have shown that specialized skills and neural systems for processing these complex cues to guide behaviour have evolved in a number of mammals and are not present exclusively in humans. Indeed, there are remarkable similarities in the ways that faces are processed by the brain in humans and other mammalian species. While human studies with brain imaging and gross neurophysiological recording approaches have revealed global aspects of the face-processing network, they cannot investigate how information is encoded by specific neural networks. Single neuron electrophysiological recording approaches in both monkeys and sheep have, however, provided some insights into the neural encoding principles involved and, particularly, the presence of a remarkable degree of high-level encoding even at the level of a specific face. Recent developments that allow simultaneous recordings to be made from many hundreds of individual neurons are also beginning to reveal evidence for global aspects of a population-based code. This review will summarize what we have learned so far from these animal-based studies about the way the mammalian brain processes the faces and the emotions they can communicate, as well as associated capacities such as how identity and emotion cues are dissociated and how face imagery might be generated. It will also try to highlight what questions and advances in knowledge still challenge us in order to provide a complete understanding of just how brain networks perform this complex and important social recognition task.

Animals↗