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PubMed2005

Dissociable roles of the bilateral anterior temporal lobe in face-name associations: an event-related fMRI study.

Previous studies have suggested the importance of bilateral anterior temporal regions in face-name associations, but there is little evidence concerning their precise role. In this fMRI study, we investigated the effects of person-related semantics (PS) and repeated learning (R) on activations in these regions during the retrieval of face-name associations. For encoding stimuli, we prepared four lists of faces. To control the factor of PS, people's and occupation names were attached to the faces in lists A and B, whereas only people's names were attached to the faces in lists C and D. To control the factor of R, the stimuli in lists A and C were learned twice, whereas the stimuli in lists B and D were learned seven times during encoding before fMRI. During fMRI after the encoding, subjects participated in the retrieval task of people's names from faces or in the retrieval task of faces from people's names. The left anterior temporal lobe was significantly activated during the retrieval of people's names from faces encoded with, compared to without, PS; whereas the right anterior temporal lobe was activated during the retrieval of people's faces from names, compared to without, this encoding. Also, activation of the left (but not the right) anterior temporal lobe was significantly reduced after R of face-name associations. These findings suggest that the three components of faces, names, and PS may be mutually mediated by the bilateral anterior temporal lobe, whose activity may be dynamically changed by the level of consolidation of face-name associations.

Adult↗
PubMed2005

Neural correlates of perceptual contributions to nondeclarative memory for faces.

Face priming is a nondeclarative memory phenomenon that can be observed when recognition is facilitated for a recently encountered face. This data-driven form of priming is distinct from conceptually driven priming. Moreover, it includes two dissociable components, the facilitated access to pre-existing representations and facilitation in perceptual processing of faces. In the present study, we measured neural correlates of perceptual contributions to face priming with event-related brain potentials. Faces appeared two times (separated by 7-17 s), while participants discriminated familiar from unfamiliar faces. Half of the initial face stimuli were inverted, thereby disrupting perceptual face processing and making possible an assessment of perceptual contributions to face priming. Whereas none of the brain waves previously linked to perceptual processing of faces showed indications of priming, such effects were observed between 200 and 600 ms at left occipito-parieto-temporal recording sites. This electrical activity was present for both unfamiliar and familiar faces. The scalp topography of this effect was consistent with sources within the temporal and occipital cortices of the left hemisphere (based on a LORETA source localization). These findings suggest that priming of perceptual face processing is subserved by prolonged neural activity from 200 to 600 ms primarily in the left hemisphere. We propose that this priming reflects facilitated selection based on second-order relations among facial features.

Adolescent↗
PubMed2006

Comparing neural correlates of configural processing in faces and objects: an ERP study of the Thatcher illusion.

In the Thatcher illusion, a face with inverted eyes and mouth looks abnormal when upright but not when inverted. Behavioral studies have shown that thatcherization of an upright face disrupts perceptual processing of the local configuration. We recorded high-density EEG from normal observers to study ERP correlates of the illusion during the perception of faces and nonface objects, to determine whether inversion and thatcherization affect similar neural mechanisms. Observers viewed faces and houses in four conditions (upright vs. inverted, and normal vs. thatcherized) while detecting an oddball category (chairs). Thatcherization delayed the N170 component over occipito-temporal cortex to faces, but not to houses. This modulation matched the illusion as it was larger for upright than inverted faces. The P1 over medial occipital regions was delayed by face inversion but unaffected by thatcherization. Finally, face thatcherization delayed P2 over occipito-temporal but not over parietal regions, while inversion affected P2 across categories. All effects involving thatcherization were face-specific. These results indicate that effects of face inversion and feature inversion (in thatcherized faces) can be distinguished on a functional as well as neural level, and that they affect configural processing of faces in different time windows.

Adult↗
PubMed2006

Distributed and interactive brain mechanisms during emotion face perception: evidence from functional neuroimaging.

Brain imaging studies in humans have shown that face processing in several areas is modulated by the affective significance of faces, particularly with fearful expressions, but also with other social signals such gaze direction. Here we review haemodynamic and electrical neuroimaging results indicating that activity in the face-selective fusiform cortex may be enhanced by emotional (fearful) expressions, without explicit voluntary control, and presumably through direct feedback connections from the amygdala. fMRI studies show that these increased responses in fusiform cortex to fearful faces are abolished by amygdala damage in the ipsilateral hemisphere, despite preserved effects of voluntary attention on fusiform; whereas emotional increases can still arise despite deficits in attention or awareness following parietal damage, and appear relatively unaffected by pharmacological increases in cholinergic stimulation. Fear-related modulations of face processing driven by amygdala signals may implicate not only fusiform cortex, but also earlier visual areas in occipital cortex (e.g., V1) and other distant regions involved in social, cognitive, or somatic responses (e.g., superior temporal sulcus, cingulate, or parietal areas). In the temporal domain, evoked-potentials show a widespread time-course of emotional face perception, with some increases in the amplitude of responses recorded over both occipital and frontal regions for fearful relative to neutral faces (as well as in the amygdala and orbitofrontal cortex, when using intracranial recordings), but with different latencies post-stimulus onset. Early emotional responses may arise around 120ms, prior to a full visual categorization stage indexed by the face-selective N170 component, possibly reflecting rapid emotion processing based on crude visual cues in faces. Other electrical components arise at later latencies and involve more sustained activities, probably generated in associative or supramodal brain areas, and resulting in part from the modulatory signals received from amygdala. Altogether, these fMRI and ERP results demonstrate that emotion face perception is a complex process that cannot be related to a single neural event taking place in a single brain regions, but rather implicates an interactive network with distributed activity in time and space. Moreover, although traditional models in cognitive neuropsychology have often considered that facial expression and facial identity are processed along two separate pathways, evidence from fMRI and ERPs suggests instead that emotional processing can strongly affect brain systems responsible for face recognition and memory. The functional implications of these interactions remain to be fully explored, but might play an important role in the normal development of face processing skills and in some neuropsychiatric disorders.

Animals↗
PubMed2006

Learning alters local face space geometry.

The effects of learning on the geometry of face space were investigated by measuring thresholds for discrimination and recognition of synthetic faces. This was based on a novel experimental technique that permitted measurement of psychometric functions for face recognition. Two major results were obtained. First, thresholds for face recognition were significantly better than thresholds for discrimination among novel faces. Second, rapid discrimination in the neighborhood of learned faces was better than discrimination near novel faces. Control experiments showed that this discrimination improvement occurred only with learned faces, and it could not be explained by generalized discrimination learning. Thus, face learning selectively alters or distorts face space in the vicinity of learned faces. This alteration may be due to an improvement in the signal/noise ratio as a result of face learning.

Discrimination, Psychological↗
PubMed2002

Domain specificity versus expertise: factors influencing distinct processing of faces.

To explore face specificity in visual processing, we compared the role of task-associated strategies and expertise on the N170 event-related potential (ERP) component elicited by human faces with the ERPs elicited by cars, birds, items of furniture, and ape faces. In Experiment 1, participants performed a car monitoring task and an animacy decision task. In Experiment 2, participants monitored human faces while faces of apes were the distracters. Faces elicited an equally conspicuous N170, significantly larger than the ERPs elicited by non-face categories regardless of whether they were ignored or had an equal status with other categories (Experiment 1), or were the targets (in Experiment 2). In contrast, the negative component elicited by cars during the same time range was larger if they were targets than if they were not. Furthermore, unlike the posterior-temporal distribution of the N170, the negative component elicited by cars and its modulation by task were more conspicuous at occipital sites. Faces of apes elicited an N170 that was similar in amplitude to that elicited by the human face targets, albeit peaking 10 ms later. As our participants were not ape experts, this pattern indicates that the N170 is face-specific, but not specie-specific, i.e. it is elicited by particular face features regardless of expertise. Overall, these results demonstrate the domain specificity of the visual mechanism implicated in processing faces, a mechanism which is not influenced by either task or expertise. The processing of other objects is probably accomplished by a more general visual processor, which is sensitive to strategic manipulations and attention.

Adult↗
PubMed2003

Covert matching of unfamiliar faces in a case of prosopagnosia: an ERP study.

In addition to their deficit in overt face recognition, patients with prosopagnosia also have difficulties in matching sequentially presented unfamiliar faces. Here we assessed the possibility that covert matching of faces was present in a case with prosopagnosia using event-related potentials (ERPs). The participants (patient FE and normal controls) were challenged with a face-identity matching task, in which they decided whether two sequentially presented photographs of unfamiliar faces represented the same person. Only internal face features were used and the two faces in a pair differed in emotional expression. FE failed to overtly match these stimuli. In contrast, the ERPs revealed evidence of covert matching. If the two faces within a pair of stimuli depicted different posers, then the response to the second face contained an enhanced N300 compared to the situation where the identity of the faces was the same. The latency of the N300 was the same as a similar component found in controls. These results suggest that some cases with prosopagnosia have a covert ability to match unfamiliar faces, with similar temporal dynamics as controls, which in contrast with the idea that a generalized slowing of face processing occurs in all cases of prosopagnosia.

Aged↗
PubMed2000

Hand response differences in a self-face identification task.

Evidence has indicated that the right frontal cortex is preferentially involved in self-face recognition. To test this further, we employed a face identification task and examined hand response differences (N=10). Pictures of famous faces were combined with pictures of the participants' faces (self) and their co-workers' faces (familiar). These images were presented as a 'movie' in which one face transformed into another. Under the first instruction set, the movies began with either the participant's face or a co-worker's face, and the sequences gradually morphed into a famous face. When told to stop the movie when the face in the sequence became famous, a significantly later 'frame' was identified when the movies were composed of self-faces and the participants responded with their left hand. When the movies started with the famous faces and participants had to stop the movie when it became their own or their familiar co-worker's image (Instruction set 2), a significantly earlier frame was identified in the 'Self: Left hand' condition. The data suggest that participants are inclined to identify images as their own when the right hemisphere is preferentially accessed.

Adult↗
PubMed2000

Event-related brain potentials distinguish processing stages involved in face perception and recognition.

OBJECTIVES: An event-related brain potential (ERP) study investigated how different processing stages involved in face identification are reflected by ERP modulations, and how stimulus repetitions and attentional set influence such effects. METHODS: ERPs were recorded in response to photographs of familiar faces, unfamiliar faces, and houses. In Part I, participants had to detect infrequently presented targets (hands), in Part II, attention was either directed towards or away from the pictorial stimuli. RESULTS: The face-specific N170 component elicited maximally at lateral temporal electrodes was not affected by face familiarity. When compared with unfamiliar faces, familiar faces elicited an enhanced negativity between 300 and 500 ms ('N400f') which was followed by an enhanced positivity beyond 500 ms post-stimulus ('P600f'). In contrast to the 'classical' N400, these effects were parietocentrally distributed. They were attenuated, but still reliable, for repeated presentations of familiar faces. When attention was directed to another demanding task, no 'N400f' was elicited, but the 'P600f' effect remained to be present. CONCLUSIONS: While the N170 reflects the pre-categorical structural encoding of faces, the 'N400f' and 'P600f' are likely to indicate subsequent processes involved in face recognition. Impaired structural encoding can result in the disruption of face identification. This is illustrated by a neuropsychological case study, demonstrating the absence of the N170 and later ERP indicators of face recognition in a prosopagnosic patient.

Adolescent↗
PubMed1985

Matching familiar and unfamiliar faces on internal and external features.

Two experiments are reported in which subjects were asked to match a photograph of a complete face and a simultaneously presented photograph of internal or external features of a face, deciding whether or not the two photographs were pictures of the same person. In experiment 1 'same' pairs were derived from different pictures of the same face, so that subjects had to match the faces and not the particular photographs used. Matches based on internal features were found to be faster for familiar than for unfamiliar faces, whereas there was no difference in reaction time between matches based on the external features of familiar and unfamiliar faces. Faster matching of internal features of familiar faces was found to hold equally for pairs of photographs that differed in orientation of the face or in facial expression. In experiment 2 'same' pairs were derived from the same photographs, which gave subjects the choice of matching on the basis of the features of the depicted faces or matching the photographs. Reaction times were faster than in experiment 1, and there were no differences between familiar and unfamiliar faces. The study confirms reports of differential saliency of the internal features of familiar faces, and shows that this only holds when stimuli are treated as faces. The finding thus reflects properties of structural rather than pictorial codes.

Face↗
PubMed2000

The face-inversion effect as a deficit in the encoding of configural information: direct evidence.

We report four experiments leading to conclusions that: (i) the face-inversion effect is mainly due to the deficits in processing of configural information from inverted faces; and (ii) this effect occurs primarily at the encoding stage of face processing, rather than at the storage stage. In experiment 1, participants discriminated upright faces differing primarily in configuration with 81% accuracy. Participants viewing the same faces presented upside down scored only 55%. In experiment 2, the corresponding discrimination rates for faces differing mainly in featural information were 91% (upright) and 90% (inverted). In experiments 3 and 4, the same faces were used in a memory paradigm. In experiment 3, a delayed matching-to-sample task was used, in which upright-face pairs differed either in configuration or features. Recognition rates were comparable to those for the corresponding upright faces in the discrimination tasks in experiments 1 and 2. However, there was no effect of delay (1 s, 5 s, or 10 s). In experiment 4, we repeated experiment 3, this time with inverted faces. Results were comparable to those of inverted conditions in experiments 1 and 2, and again there was no effect of delay. Together these results suggest that an 'encoding bottleneck' for configural information may be responsible for the face-inversion effect in particular, and memory for faces in general.

Face↗
PubMed2005

The respective role of low and high spatial frequencies in supporting configural and featural processing of faces.

One distinctive feature of processing faces, as compared to other categories, is thought to be the large dependence on configural cues such as the metric relations among features. To test the role of low spatial frequencies (LSFs) and high spatial frequencies (HSFs) in configural and featural processing, subjects were presented with triplets of faces that were filtered to preserve either LSFs (below 8 cycles per face width), HSFs (above 32 cycles per face width), or the full frequency spectrum. They were asked to match one of two probe faces to a target face. The distractor probe face differed from the target either configurally, featurally, or both featurally and configurally. When the difference was at the configural level, performance was better with LSF faces than with HSF faces. In contrast, with a featural difference, a strong performance advantage was found for HSF faces as compared to LSF faces. These results support the dominant role that LSFs play in the configural processing of faces, whereas featural processing is largely dependent on HSFs.

Adult↗
PubMed1995

On the modularity of face recognition: the riddle of domain specificity.

The present paper focuses on the modular attributes of face recognition, defined in terms of domain specificity. Domain specificity is examined by looking into the innate nature of face recognition, the special effects related to the recognition of inverted faces, the specificity of electrophysiological responsivity to facial stimuli, and the specific impairment in face recognition associated with localized brain damage. Converging evidence from these sources seems to consistently show that face recognition is not qualitatively unique, as it proceeds in a manner similar to the recognition of other visuospatial objects. However, it seems to be special in that it may involve specific mechanisms dedicated to face recognition. Among infants, differential responsivity to faces and to other objects in terms of age of onset, attraction and course of development, seems to indicate the operation of a special process. Unusual inversion effects in face recognition might be due to the special expertise that humans develop for recognizing upright faces. Face-selective single unit responses in the monkey's brain implies the existence in the visual system of cells which are exclusively dedicated to the processing of facial stimuli. Finally, in prosopagnosia localized brain damage is linked to a specific inability to recognize familiar faces. Taken together, the data seem to show that some elements in the process of face recognition are domain specific, and in that sense, modular.

Agnosia↗
PubMedDate not supplied

An anthropological model for automatic recognition of the male human face.

The human face is a characteristic pattern most familiar to us when distinguishing people. Although recognizing human faces is one of our everyday activities, we are mostly not aware how the mechanisms of recognition actually work. Attempts to recognize the human face by machine are rarer (less frequent) than those of the recognition of some other phenomena in everyday life. This paper describes the automated analysis of a human face from the grey level picture, defined as an individual description of a face, given in the form of its sub-objects and the relations among them. The model-based analysis is founded on the anthropological model of a human face that incorporates 19 facial parameters of a male face in norma facialis. On the basis of these parameters it is possible to analyse, recognize and identify the human face. The contour image is used as an input to the pattern analysis program. Some algorithms for the search of characteristic face areas are presented. The Hough transform for an ellipse is used to determine the position of the head in a grey image, and to define the eye region within a face. The integral projections of the contour picture are proved to be useful techniques for picture processing to define the nose and the mouth regions within a face. Furthermore, a few algorithms for the precise determination of the facial parameters based on sharp edge transitions are developed. The method is illustrated using photographs of human faces from our data base and the results obtained are also given. The system is realized on a PC/AT computer.

Algorithms↗
PubMed2006

Higher face recognition ability in girls: Magnified by own-sex and own-ethnicity bias.

Earlier studies on adults have shown sex differences in face recognition. Women tend to recognise more faces of other women than men do, whereas there are no sex differences with regard to male faces. In order to test the generality of earlier findings and to examine potential reasons for the observed pattern of sex differences, two groups of Swedish 9-year-old children (n = 101 and n = 96) viewed faces of either Swedish or Bangladeshi children and adults for later recognition. Results showed that girls outperformed boys in recognition of female faces, irrespective of ethnicity and age of the faces. Boys and girls recognised Swedish male faces to an equal extent, whereas girls recognised more Bangladeshi male faces than boys did. These results indicate that three factors explain the magnitude of sex differences in face recognition: an overall female superior face recognition ability, the correspondence between the sex of viewer and the gender of the face, and prior knowledge of the ethnicity of the face.

Adult↗
PubMed1999

Recognizing unfamiliar faces: the effects of distinctiveness and view.

Three experiments are reported in which the effects of viewpoint on the recognition of distinctive and typical faces were explored. Specifically, we investigated whether generalization across views would be better for distinctive faces than for typical faces. In Experiment 1 the time to match different views of the same typical faces and the same distinctive faces was dependent on the difference between the views shown. In contrast, the accuracy and latency of correct responses on trials in which two different faces were presented were independent of viewpoint if the faces were distinctive but were view-dependent if the faces were typical. In Experiment 2 we tested participants' recognition memory for unfamiliar faces that had been studied at a single three-quarter view. Participants were presented with all face views during test. Finally, in Experiment 3, participants' were tested on their recognition of unfamiliar faces that had been studied at all views. In both Experiments 2 and 3 we found an effect of distinctiveness and viewpoint but no interaction between these factors. The results are discussed in terms of a model of face representation based on an inter-item similarity in which the representations are view specific.

Adult↗
PubMed2006

Sub-exemplar shape tuning in human face-related areas.

Although human face recognition performance shows high selectivity, even for unfamiliar faces, the neuronal circuitry underlying this high performance is poorly understood. Two extreme alternatives can be considered: either a "labeled-line" principle, in which subtle changes in face images lead to activation of differently tuned neuronal populations, or a coarse coding principle, where the high face selectivity is coded by the relative activation of broadly tuned neurons. In this study, we set to parametrically examine the shape and selectivity profile of face-related visual areas. To that end, we applied the functional magnetic resonance (fMR)-adaptation paradigm. Unfamiliar face stimuli were morphed into sets ranging from identical faces, through subtle morphing, to completely different exemplars. The fusiform face area (FFA) revealed high face sensitivity, so that even facial images perceived as belonging to the same individual (<35%) were sufficient to produce full recovery from adaptation. Interestingly, the psychophysical detectability of facial differences paralleled the release from fMR-adaptation. These results support the labeled-line model where high sensitivity to face changes is paralleled by narrow tuning of neuronal populations selective to each face image, and they suggest that fMR-adaptation is closely related to behavior. The results bear strong implications to the nature of face-related neuronal responses.

Adaptation, Physiological↗
PubMed1992

Cognitive mechanisms of face processing.

Evidence from natural and induced errors of face recognition, from the effects of different cues on resolving errors, and from the latencies to make different decisions about seen faces, all suggest that familiar face recognition involves a fixed, invariant sequence of stages. To recognize a familiar face, a perceptual description of a seen face must first activate a long-standing representation of the appearance of the face of the familiar person. 'Semantic' knowledge about such things as the person's occupation and personality are accessed next, followed, in the final stage, by the name. Certain factors affect the ease of familiar face recognition. Faces seen in the recent past are recognized more readily (repetition priming), as are distinctive faces, and faces preceded by those of related individuals (associative priming). Our knowledge of these phenomena is reviewed for the light it can shed upon the mechanisms of face recognition. Four aspects of face recognition--graded similarity effects and part-to-whole completion in repetition priming, prototype extraction with simultaneous retention of information about individual exemplars, and distinctiveness effects in classification and identification--are proposed as being compatible with distributed memory accounts of cognitive representations.

Association Learning↗