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Effects of geometric distortions on face-recognition performance.

The importance of 'configural' processing for face recognition is now well established, but it remains unclear precisely what it entails. Through four experiments we attempted to clarify the nature of configural processing by investigating the effects of various affine transformations on the recognition of familiar faces. Experiment 1 showed that recognition was markedly impaired by inversion of faces, somewhat impaired by shearing or horizontally stretching them, but unaffected by vertical stretching of faces to twice their normal height. In experiment 2 we investigated vertical and horizontal stretching in more detail, and found no effects of either transformation. Two further experiments were performed to determine whether participants were recognising stretched faces by using configural information. Experiment 3 showed that nonglobal vertical stretching of faces (stretching either the top or the bottom half while leaving the remainder undistorted) impaired recognition, implying that configural information from the stretched part of the face was influencing the process of recognition--ie that configural processing involves global facial properties. In experiment 4 we examined the effects of Gaussian blurring on recognition of undistorted and vertically stretched faces. Faces remained recognisable even when they were both stretched and blurred, implying that participants were basing their judgments on configural information from these stimuli, rather than resorting to some strategy based on local featural details. The tolerance of spatial distortions in human face recognition suggests that the configural information used as a basis for face recognition is unlikely to involve information about the absolute position of facial features relative to each other, at least not in any simple way.

Adult↗

Analyses of facial attractiveness on feminised and juvenilised faces.

We conducted two experiments to investigate the psychological factors affecting the attractiveness of composite faces. Feminised or juvenilised Japanese faces were created by morphing between average male and female adult faces or between average male (female) adult and boy (girl) faces. In experiment 1, we asked the participants to rank the attractiveness of these faces. The results showed moderately juvenilised faces to be highly attractive. In experiment 2, we analysed the impressions the participants had of the composite faces by the semantic-differential method and determined the factors that largely affected attractiveness. On the basis of the factor scores, we plotted the faces in factor spaces and analysed the locations of attractive faces. We found that most of the attractive juvenilised faces involved impressions corresponding to an augmentation of femininity, characterised by the factors of 'elegance', 'mildness', and 'youthfulness', which the attractive faces potentially had.

Adult↗

An encoding advantage for own-race versus other-race faces.

Studies have shown that individuals are better able to recognise the faces of people from their own race than the faces of people from other races. Although the so-called own-race effect has been generally regarded as an advantage in recognition memory, differences in the processing of the own-race versus other-race faces might also be found at the earlier stages of perceptual encoding. In this study, the perceptual basis of the own-race effect was investigated by generating a continuum of images by morphing an East Asian parent face with a Caucasian parent face. In a same/different discrimination task, East Asian and Caucasian participants judged whether the morph faces were physically identical to, or different from, their parent faces. The results revealed a significant race-of-participant by race-of-face interaction such that East Asian participants were better able to discriminate East Asian faces, whereas Caucasian participants were better able to discriminate Caucasian faces. These results indicate that an own-race advantage occurs at the encoding stage of face processing.

Adult↗

When feature information comes first! Early processing of inverted faces.

We investigated the early stages of face recognition and the role of featural and holistic face information. We exploited the fact that, on inversion, the alienating disorientation of the eyes and mouth in thatcherised faces is hardly detectable. This effect allows featural and holistic information to be dissociated and was used to test specific face-processing hypotheses. In inverted thatcherised faces, the cardinal features are already correctly oriented, whereas in undistorted faces, the whole Gestalt is coherent but all information is disoriented. Experiment 1 and experiment 3 revealed that, for inverted faces, featural information processing precedes holistic information. Moreover, the processing of contextual information is necessary to process local featural information within a short presentation time (26 ms). Furthermore, for upright faces, holistic information seems to be available faster than for inverted faces (experiment 2). These differences in processing inverted and upright faces presumably cause the differential importance of featural and holistic information for inverted and upright faces.

Adult↗

Neuropsychological impairment of face recognition units.

Despite the absence of "conscious", overt identification, some patients with face recognition impairments continue covertly to process information regarding face familiarity. The fact that by no means all patients show these covert effects has led to the suggestion that indirect recognition tasks may help in identifying different types of face recognition impairment. The present report describes a number of experiments with the patient NR, who, after a closed head injury, has been severely impaired at recognizing familiar faces. Investigations mostly failed to show overt or covert face recognition, but NR performed at an above-chance level in selecting the familiar face on a task requiring a forced-choice between a familiar and an unfamiliar face. This discrepancy between a degree of rudimentary overt recognition and absence of covert effects on most indirect tests was addressed using a cross-domain identity priming paradigm. This examined separately the possibility of preserved recognition for faces that NR consistently chose correctly in a forced-choice familiarity decision and those on which he performed at chance level. Priming effects were apparent only for the faces that were consistently chosen as "familiar" in forced-choice. We suggest that NR's stored representations of familiar faces are degraded, so that face recognition is possible only via a limited set of relatively preserved representations able to support a rudimentary form of overt recognition and to facilitate performance in matching and priming tasks.

Adult↗

Short article one's own face is hard to ignore.

One's own face possesses two properties that make it prone to grab attention: It is a face, and, in addition, it is a self-referential stimulus. The question of whether the self-face is actually an especially attention-grabbing stimulus was addressed by using a face-name interference paradigm. We investigated whether interference from a flanking self-face on the processing of a target classmate's name was stronger than interference from a classmate's flanking face on the processing of one's own name as the target. In a control condition a third familiar face served as the flanker for both decisions from the participant's own name and from the classmate's name. The presentation of the self-face as a flanker produced significantly more interference on the identification of a classmate's name than the presentation of that classmate's face did on the identification of one's own name. This result was due to the interfering power of the self-face and not to a particular resistance of one's name to interfering facial stimuli. We argue that the emotional value or the high familiarity of one's own face may explain its attention-grabbing property.

Adolescent↗

Identification of famous faces and famous names in early Alzheimer's disease. Relationship to anterograde episodic and general semantic memory.

We assessed remote memory in 33 patients with dementia of Alzheimer's type (DAT) with Mini-Mental State Examination (MMSE) scores between 17 and 30, and 30 matched controls using a Famous Faces Test and Famous Names Test designed to assess face recognition, identification and naming, and name recognition and identification, respectively, together with a range of anterograde episodic and semantic memory tests. Patients with DAT were impaired on all components of the remote memory tests, i.e. famous face recognition, identification and naming, and famous name recognition and identification. There was also evidence of a modest temporal gradient, with relatively greater impairment of more recent memory, which may be artefactual resulting from the very insidious onset of their anterograde amnesia. In contrast to the uniform impairment of anterograde memory, there was considerable heterogeneity in performance on remote memory. Although the DAT patient group's performance on remote memory measures was impaired with respect to controls, some patients had significant impairment on all measures, whereas others had intact remote memory. Overall, there was only a weak correlation between dementia severity and remote memory, and no correlation between performance on the Faces and Names tests and measures of anterograde memory. At a cognitive level, the deficit in face and name processing in DAT involved recognition, identification and naming. This would suggest that so called 'face and name recognition units', semantic knowledge of famous persons and post-semantic processing are all affected by the disease. There was also supporting evidence for the concept that recognition of famous faces and names both draw on common sources. Similar results were found for face and name identification. This suggests that face and name recognition units are closely linked, and that identification of a face or name accesses the same central pool of semantic knowledge regarding the famous person. Performance on famous names tests correlated, to a limited degree, with that on general semantic tests, suggesting that knowledge of famous people, at least as accessed by names, is associated with general semantic memory. By contrast, no correlation was found between performance on the famous faces and on other general semantic tasks.

Aged↗

Direct comparison of the neural substrates of recognition memory for words and faces.

For the purpose of identifying the relatively specific brain regions related to word and face recognition memory on the one hand and the regions common to both on the other, regional cerebral blood flow associated with different cognitive tasks for recognition memory was examined using [H215O]PET in healthy volunteers. The tasks consisted of recognizing two types of stimuli (faces and words) in two conditions (novel and familiar), and two baseline tasks (reading words and gender classification). The statistical analyses used to identify the specific regions consisted of three subtractions: novel words minus novel faces, familiar words minus familiar faces, and reading words minus gender classification. These analyses revealed relative differences in the brain circuitry used for recognizing words and for recognizing faces within a defined level of familiarity. In order to find the regions common to both face and word recognition, overlapping areas in four subtractions (novel words minus reading words, novel faces minus gender classification, familiar words minus reading words, and familiar faces minus gender classification) were identified. The results showed that the activation sites in word recognition tended to be lateralized to the left hemisphere and distributed as numerous small loci, and particularly included the posterior portion of the left middle and inferior temporal gyri. These regions may be related to lexical retrieval during written word recognition. In contrast, the activated regions for face recognition tended to be lateralized to the right hemisphere and located in a large aggregated area, including the right lingual and fusiform gyri. These findings suggest that strikingly different neural pathways are engaged during recognition memory for words and for faces, in which a critical role in discrimination is played by semantic cueing and perceptual loading, respectively. In addition, the investigation of the regions common to word and face recognition indicates that the anterior and posterior cingulate have dissociable functions in recognition memory that vary with familiarity, and that the cerebellum may serve as the co-ordinator of all four types of recognition memory processes.

Adult↗

N170 or N1? Spatiotemporal differences between object and face processing using ERPs.

The ERP component N170 is face-sensitive, yet its specificity for faces is controversial. We recorded ERPs while subjects viewed upright and inverted faces and seven object categories. Peak, topography and segmentation analyses were performed. N170 was earlier and larger to faces than to all objects. The classic increase in amplitude and latency was found for inverted faces on N170 but also on P1. Segmentation analyses revealed an extra map found only for faces, reflecting an extra cluster of activity compared to objects. While the N1 for objects seems to reflect the return to baseline from the P1, the N170 for faces reflects a supplement activity. The electrophysiological 'specificity' of faces could lie in the involvement of extra generators for face processing compared to objects and the N170 for faces seems qualitatively different from the N1 for objects. Object and face processing also differed as early as 120 ms.

Adult↗

Electrophysiological evidence for temporal dissociation between spatial attention and sensory competition during human face processing.

Scalp event-related potential (ERP) studies in humans indicate that face processes taking place between 130 and 170 ms after stimulus onset at posterior sites (N170) are strongly reduced when another face stimulus is processed concurrently or has been presented shortly before for a prolonged period. These observations suggest that neural representations of individual faces compete in the occipitotemporal cortex as early as 130 ms. Here, we tested the respective role of spatial attention and sensory competition in accounting for the amplitude reduction of the N170 during concurrent face stimulation. ERPs time locked to a lateralized face stimulus were recorded while subjects were fixating either a face or a controlled scrambled-face stimulus (context factor) and were engaged in either a high- or a low-attentional load task at fixation (task factor). The N170 amplitude to the lateralized face stimulus was reduced both when the central stimulus was a face compared with a scrambled face and when the attentional load at fixation was high. However, these effects of context and task factors were largely additive. Most importantly, spatial attention modulated visual processes as early as 80 ms after stimulus onset, whereas sensory competition effects started at about 130 ms. These results provide strong evidence that the N170 in response to faces is modulated by spatial attention, and also that spatial attention and sensory competition do not reflect the same mechanisms of early selection of visual information in the extrastriate cortex.

Adult↗

Developmental prosopagnosia: should it be taken at face value?

This study presents a rare case of developmental prosopagnosia. Structural magnetic resonance imaging (MRI) revealed no overt brain abnormalities. EP's basic visual skills and visual memory were intact, as was his ability to judge age, sex and expression from faces, identify facial parts, and make face/non-face decisions. EP was impaired at recognizing famous and very familiar faces and describing visual images of famous faces. He also displayed an anterograde memory impairment for recently studied faces, and performed poorly on tests of unfamiliar face matching, most notably for chimeric faces. It is suggested that EP may be deficient at encoding configural representations of faces. EP appears to have a "pure" (i.e. specific to faces) prosopagnosia, as he shows normal object recognition from unusual viewpoints, good gestalt completion for objects, but not for faces, normal visual imagery for objects but not for faces, a disruption of the inversion effect for faces but not for houses, and performs within the normal range on tests of within-category discriminations, even with unique exemplars of object categories such as famous buildings.

Adult↗

Transient inability to distinguish between faces: electrophysiologic studies.

It is not known with certainty at which level of face processing by the cortex the distinction between a familiar and an unfamiliar face is made. Subdural electrodes were implanted under the fusiform gyrus of the right temporal lobe in a patient who developed an unusual inability to distinguish differences between faces as part of the epileptic aura ("all faces looked the same"). A cortical region located posterior to the epileptic focus was identified that exhibited a maximum evoked response to the presentation of facial images (N165), but not to objects, scenes, or character strings. Evoked potentials elicited by a variety of visual images indicated that any perturbation away from novel whole-face stimuli produced submaximal responses from this region of the right temporal lobe. Electrical stimulation of this region resulted in an impairment of face discrimination. It was found that presentation of familiar faces (grandmother, treating physician) produced a different response from that observed for novel faces. These observations demonstrate that within 165 msec of face presentation, and before the conscious precept of face familiarity has formed, this cortical region has already begun to distinguish between a familiar and an unfamiliar face.

Adult↗

Perception of age in adult Caucasian male faces: computer graphic manipulation of shape and colour information.

This study investigated visual cues to age by using facial composites which blend shape and colour information from multiple faces. Baseline measurements showed that perceived age of adult male faces is on average an accurate index of their chronological age over the age range 20-60 years. Composite images were made from multiple images of different faces by averaging face shape and then blending red, green and blue intensity (RGB colour) across comparable pixels. The perceived age of these composite or blended images depended on the age bracket of the component faces. Blended faces were, however, rated younger than their component faces, a trend that became more marked with increased component age. The techniques used provide an empirical definition of facial changes with age that are biologically consistent across a sample population. The perceived age of a blend of old faces was increased by exaggerating the RGB colour differences of each pixel relative to a blend of young faces. This effect on perceived age was not attributable to enhanced contrast or colour saturation. Age-related visual cues defined from the differences between blends of young and old faces were applied to individual faces. These transformations increased perceived age.

Adult↗

The face behind the mask: a developmental study.

Faces are a rich and available source of social information, and the representation for faces is robust in adults (i.e. the face detection effect; Purcell & Stewart, 1988). The current study compared the developmental trajectory of the robustness of face perception against the trajectory for a non-face object. Participants (5-35 years old) were presented with rapid (17 and 33 millisecond) presentations of face and house stimuli and were instructed to identify the object category of the stimulus (face or house). There was an interaction between object type and age such that the developmental slope for face identification was steeper than the slope for house identification for the 17-millisecond presentation. These data show that faces are processed in a different way than a non-face object during the period from middle childhood through adolescence and adulthood, and this differential processing may involve the massive amount of exposure we have to faces.

Adolescent↗

Right cerebral hemisphere superiority for recognizing the internal and external features of famous faces.

Right-handed male and female subjects were asked to identify bilaterally presented famous faces from an upright display of all the faces used in the experiment, under four conditions: these involved presentation of upright external features, upright internal features, upright whole faces, and inverted whole faces. The task was one of identification in the sense of picking out presented faces from a display of all the possible faces, and did not require explicit naming of the famous people. Left visual hemifield superiorities were found for upright external features, upright internal features, and upright whole faces, which did not vary across these three conditions. Overall performance levels did vary, with whole faces better identified than internal features, which were in turn better identified than external features. The presentation of inverted whole faces led to poorer overall performance than for upright faces, and no visual hemifield asymmetry. These results show that the right cerebral hemisphere is better able than the left to recognize known faces from both internal and external features.

Cerebral Cortex↗

Neuronal correlates of face identification in the monkey anterior temporal cortical areas.

To investigate the neuronal basis underlying face identification, the activity of face neurons in the anterior superior temporal sulcus (STS) and the anterior inferior temporal gyrus (ITG) of macaque monkeys was analyzed during their performance of a face-identification task. The face space was composed by the activities of face neurons during the face-identification task, based on a multidimensional scaling (MDS) method; the face space composed by the anterior STS neurons represented facial views, whereas that composed by the anterior ITG neurons represented facial identity. The temporal correlation between the behavioral reaction time of the animal and the latency of face-related neuronal responses was also analyzed. The response latency of some of the face neurons in the anterior ITG exhibited a significant correlation with the behavioral reaction time, whereas this correlation was not significant in the anterior STS. The correlation of the latency of face-related neuronal responses in the anterior ITG with the behavioral reaction time was not found to be attributed to the correlation between the response latency and the magnitude of the neuronal responses. The present results suggest that the anterior ITG is closely related to judgments of facial identity, and that the anterior STS is closely related to analyses of incoming perceptual information; face identification in monkeys might involve interactions between the two areas.

Action Potentials↗

Neural responses to facial expression and face identity in the monkey amygdala.

The amygdala is purported to play an important role in face processing, yet the specificity of its activation to face stimuli and the relative contribution of identity and expression to its activation are unknown. In the current study, neural activity in the amygdala was recorded as monkeys passively viewed images of monkey faces, human faces, and objects on a computer monitor. Comparable proportions of neurons responded selectively to images from each category. Neural responses to monkey faces were further examined to determine whether face identity or facial expression drove the face-selective responses. The majority of these neurons (64%) responded both to identity and facial expression, suggesting that these parameters are processed jointly in the amygdala. Large fractions of neurons, however, showed pure identity-selective or expression-selective responses. Neurons were selective for a particular facial expression by either increasing or decreasing their firing rate compared with the firing rates elicited by the other expressions. Responses to appeasing faces were often marked by significant decreases of firing rates, whereas responses to threatening faces were strongly associated with increased firing rate. Thus global activation in the amygdala might be larger to threatening faces than to neutral or appeasing faces.

Aggression↗

III. Electrophysiological studies of face processing in Williams syndrome.

Williams Syndrome (WMS) is a genetically based disorder characterized by pronounced variability in performance across different domains of cognitive functioning. This study examined brain activity linked to face-processing abilities, which are typically spared in individuals with WMS. Subjects watched photographic pairs of upright or inverted faces and indicated if the second face matched or did not match the first face. Results from a previous study with normal adults showed dramatic differences in the timing and distribution of ERP effects linked to recognition of upright and inverted faces. In normal adults, upright faces elicited ERP differences to matched vs. mismatched faces at approximately 320 msec (N320) after the onset of the second stimulus. This "N320" effect was largest over anterior regions of the right hemisphere. In contrast, the mismatch/match effect for inverted faces consisted of a large positive component between 400 and 1000 msec (P500) that was largest over parietal regions and was symmetrical. In contrast to normal adults, WMS subjects showed an N320-mismatch effect for both upright and inverted faces. Additionally, the WMS subjects did not display the N320 right-hemisphere asymmetry observed in the normal adults. WMS subjects also displayed an abnormally small negativity at 100 msec (N100) and an abnormally large negativity at 200 msec (N200) to both upright and inverted faces. This ERP pattern was observed in all subjects with WMS but was not observed in the normal controls. These results may be linked to increased attention to faces in subjects with WMS and might be specific to the disorder. These results were consistent with our ERP studies of language processing in WMS, which suggested abnormal cerebral specialization for spared cognitive functions in individuals with WMS.

Adolescent↗