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PubMed1983

Integration of schematic faces and other complex objects in schizophrenia.

Twenty-one acute schizophrenic patients and 26 neurotic patients sorted each of six sets of 15 objects into three groups. A set consisted either of schematic faces, nonsense objects, or histoforms, each composed of five independently varying features. For the faces and nonsense objects these features could be integrated into a whole, whereas for the histoforms they could not. The distribution of four of the features was such that a set could be divided into three groups. The fifth feature either remained constant and had no effect on sorting performance or it varied randomly and acted as a distractor. Performance was assessed from the variance in common between the grouping actually present in a set and the grouping produced by the subject. For the control patients faces were sorted much better than histoforms if no distractor was present. However, performance with faces was massively impaired by a distractor while performance with histoforms was not. For the schizophrenic patients faces were not sorted better than histoforms and the effect of distraction was similar for every type of material. The performance of the controls suggest that the gestalt quality of the faces dominated over their constituent details. This enabled more features to be handled at once, thus achieving better sorting with faces than histoforms. However, it also made it more difficult for subjects to ignore a distracting component in the faces. The performance of the schizophrenics suggests that for them the integrated gestalt of the face was not dominant over its components.

Attention↗

PubMedDate not supplied

Attitudes to face transplantation: results of a public engagement exercise at the Royal Society Summer Science Exhibition.

Hettiaratchy and Butler (Lancet 2002;360:5-6) framed face transplantation as the next logical step on the reconstructive ladder for severe facial injury, in particular, pan-facial burns. The procedure formed the basis for a Royal College of Surgeons of England working party report. Ethical, surgical, and psychological issues were identified as research priorities before face transplantation is attempted in the United Kingdom. Public engagement is a vital mechanism if people are to be informed about the risks and benefits of the technique and ultimately to be able to consent to either receiving or donating facial tissue. To sample public opinion about the procedure, 304 people attending the Royal Society Summer Science Exhibition were sampled by online questionnaire to determine their attitude toward face transplantation. Although people were more cautious about face transplantation when comparing this with solid-organ transplantation, most of the sample were in favor of the procedure, whether receiving a donor face or donating their own face after their death. Only 10% were against the idea in principle. Concerns about altered identity were not a barrier to face transplantation for 69% of the sample, with most people appropriately identifying the long-term problems of immunosuppression as the issue that most concerned them. There is a substantial population of people who, given the right circumstances, would contemplate face transplantation for themselves and would be willing to donate their own face for transplantation after their death.

Adolescent↗

PubMed2005

Face recognition in the elderly.

PURPOSE: The purpose of this study was to assess face recognition ability in a large sample of elders (n=572, mean age=78.1 years) and to identify factors that affect performance. METHODS: Face recognition was measured by presenting standardized faces of varying sizes to simulate normal-sized faces at different viewing distances. Subjects were asked to identify the name of the person and their facial expression. Threshold equivalent viewing distance (EVD) was calculated. High- and low-contrast acuity, contrast sensitivity, low-contrast/low-luminance acuity, disability glare, stereoacuity, and visual field measures (with and without an attentional task) were also measured. These vision measures, along with demographic information (age, sex, education) and cognitive status, were included in a multiple regression analysis to determine which factors predicted task performance. RESULTS: This cross-sectional sample of elders showed significant declines in face recognition with age. Mean threshold EVD ranged from 8.0 m for participants<or=70 years of age to 2.2 meters for those over 85 years. Multiple regression analysis revealed that age, sex, years of education, spatial vision, and cognitive status were all significant predictors of face recognition, accounting for approximately 46% of the variability. Spatial vision (high-contrast acuity) and age were the best predictors. Although each spatial vision measure was significantly correlated with face recognition, adding low-contrast or contrast sensitivity measures to the regression analysis explained no more variance than age and high-contrast acuity alone. CONCLUSIONS: The marked decline in face recognition ability in elders is related to declines in spatial vision and cognitive status. All spatial vision measures have similar predictive ability for face recognition.

Aged↗

PubMed1997

Are faces of different species perceived categorically by human observers?

What are the species boundaries of face processing? Using a face-feature morphing algorithm, image series intermediate between human, monkey (macaque), and bovine faces were constructed. Forced-choice judgement of these images showed sharply bounded categories for upright face images of each species. These predicted the perceptual discrimination boundaries for upright monkey-cow and cow-human images, but not human-monkey images. Species categories were also well-judged for inverted face images, but these did not give sharpened discrimination (categorical perception) at the category boundaries. While categorical species judgements are made reliably, only the distinction between primate faces and cow faces appears to be categorically perceived, and only in upright faces. One inference is that humans may judge monkey faces in terms of human characteristics, albeit distinctive ones.

Adult↗

PubMed2004

Face recognition by applying wavelet subband representation and kernel associative memory.

In this paper, we propose an efficient face recognition scheme which has two features: 1) representation of face images by two-dimensional (2-D) wavelet subband coefficients and 2) recognition by a modular, personalised classification method based on kernel associative memory models. Compared to PCA projections and low resolution "thumb-nail" image representations, wavelet subband coefficients can efficiently capture substantial facial features while keeping computational complexity low. As there are usually very limited samples, we constructed an associative memory (AM) model for each person and proposed to improve the performance of AM models by kernel methods. Specifically, we first applied kernel transforms to each possible training pair of faces sample and then mapped the high-dimensional feature space back to input space. Our scheme using modular autoassociative memory for face recognition is inspired by the same motivation as using autoencoders for optical character recognition (OCR), for which the advantages has been proven. By associative memory, all the prototypical faces of one particular person are used to reconstruct themselves and the reconstruction error for a probe face image is used to decide if the probe face is from the corresponding person. We carried out extensive experiments on three standard face recognition datasets, the FERET data, the XM2VTS data, and the ORL data. Detailed comparisons with earlier published results are provided and our proposed scheme offers better recognition accuracy on all of the face datasets.

Association Learning↗

PubMed2005

Face recognition using laplacianfaces.

We propose an appearance-based face recognition method called the Laplacianface approach. By using Locality Preserving Projections (LPP), the face images are mapped into a face subspace for analysis. Different from Principal Component Analysis (PCA) and Linear Discriminant Analysis (LDA) which effectively see only the Euclidean structure of face space, LPP finds an embedding that preserves local information, and obtains a face subspace that best detects the essential face manifold structure. The Laplacianfaces are the optimal linear approximations to the eigenfunctions of the Laplace Beltrami operator on the face manifold. In this way, the unwanted variations resulting from changes in lighting, facial expression, and pose may be eliminated or reduced. Theoretical analysis shows that PCA, LDA, and LPP can be obtained from different graph models. We compare the proposed Laplacianface approach with Eigenface and Fisherface methods on three different face data sets. Experimental results suggest that the proposed Laplacianface approach provides a better representation and achieves lower error rates in face recognition.

Algorithms↗

PubMed2005

Mechanisms of face perception in humans: a magneto- and electro-encephalographic study.

We have been studying the underlying mechanisms of face perception in humans using magneto- (MEG) and electro-encephalography (EEG) including (1) perception by viewing the static face, (2) differences in perception by viewing the eyes and whole face, (3) the face inversion effect, (4) the effect of gaze direction, (5) perception of eye motion, (6) perception of mouth motion, and (7) the interaction between auditory and visual stimuli related to the vowel sounds. In this review article, we mainly summarize our results obtained on 3, 5, and 6 above. With the presentation of both upright and inverted unfamiliar faces, the inferior temporal cortex (IT) centered on the fusiform gyrus, and the lateral temporal cortex (LT) near the superior temporal sulcus were activated simultaneously, but independently, between 140 and 200 ms post-stimulus. The right hemisphere IT and LT were both active in all subjects, and those in the left hemisphere in half of the subjects. Latencies with inverted faces relative to those with upright faces were longer in the right hemisphere, and shorter in the left hemisphere. Since the activated regions under upright and those under inverted face stimuli did not show a significant difference, we consider that differences in processing upright versus inverted faces are attributable to temporal processing differences rather than to processing of information by different brain regions. When viewing the motion of the mouth and eyes, a large clear MEG component, 1M (mean peak latency of approximately 160 ms), was elicited to both mouth and eye movement, and was generated mainly in the occipito-temporal border, at human MT/V5. The 1M to mouth movement and the 1M to eye movement showed no significant difference in amplitude or generator location. Therefore, our results indicate that human MT/V5 is active in the perception of both mouth and eye motion, and that the perception of movement of facial parts is probably processed similarly.

Adult↗

PubMed2006

Effects of personal familiarity on early neuromagnetic correlates of face perception.

This study investigated effects of familiarity and orientation on face processing by means of magnetoencephalography. Participants were presented with photographs of personally familiar, famous and unfamiliar faces in both upright and inverted orientation. They had to decide whether faces were familiar by means of manual yes/no responses. Independent of orientation, we observed a clear modulation of the M170 by familiarity, with personally familiar faces evoking larger amplitudes than unknown faces. The M170 was also sensitive to orientation, with larger amplitudes for inverted than upright faces. Moreover, the M170 exhibited larger amplitudes over the right than over the left hemisphere, but this asymmetry was present for upright faces only. The present data suggest that at least for personally familiar faces, neural correlates of identification start no later than approximately 170 ms, and underline a special role of the right hemisphere for faces in their typical upright orientation.

Adult↗

PubMed2006

Probing the visual representation of faces with adaptation: A view from the other side of the mean.

Sensory adaptation and visual aftereffects have long given insight into the neural codes underlying basic dimensions of visual perception. Recently discovered perceptual adaptation effects for complex shapes like faces can offer similar insight into high-level visual representations. In the experiments reported here, we demonstrated first that face adaptation transfers across a substantial change in viewpoint and that this transfer occurs via processes unlikely to be specific to faces. Next, we probed the visual codes underlying face recognition using face morphs that varied selectively in reflectance or shape. Adaptation to these morphs affected the perception of "opposite" faces both from the same viewpoint and from a different viewpoint. These results are consistent with high-level face representations that pool local shape and reflectance patterns into configurations that specify facial appearance over a range of three-dimensional viewpoints. These findings have implications for computational models of face recognition and for competing neural theories of face and object recognition.

Discrimination, Psychological↗

PubMed2006

Face memory in MRI-positive and MRI-negative temporal lobe epilepsy.

PURPOSE: Effects of MRI-positive (MRI(+)) as compared to MRI-negative (MRI(-)) temporal lobe epilepsy (TLE) on face memory are not yet known. METHODS: We studied 24 MRI(-) (11 right/13 left) and 20 MRI(+) (13 right/7 left) TLE patients, 12 generalized epilepsy patients, and 12 healthy subjects undergoing diagnostic workup with 24-72-h Video-EEG-monitoring. Twenty faces were shown, and had to be recognized from 40 faces immediately and after a 24-h delay. RESULTS: MRI(+) and MRI(-) right TLE (RTLE) patients showed deficits in face recognition compared to controls or generalized epilepsy, consistent with right temporal lobe dominance for face recognition. MRI(+) RTLE patients had deficits in both immediate and delayed recognition, while MRI(-) RTLE patients showed delayed recognition deficits only. The RTLE groups showed comparable delayed recognition deficits. Separate analyses in which the MRI(+) group included patients with hippocampal sclerosis only, did not alter results. Furthermore, MRI(-) RTLE had a worse delayed recognition than MRI(-) left TLE (LTLE). On the other hand, MRI(+) RTLE did not differ from MRI(+) LTLE in delayed recognition. Combining MRI(-) and MRI(+) TLE groups, we found differences between RTLE and LTLE in delayed, but not immediate face recognition. CONCLUSIONS: Our results suggest that a delayed recognition condition might be superior to immediate recognition tests in detecting face memory deficits in MRI(-) RTLE patients. This might explain why former studies in preoperative patients did not observe an immediate face recognition dominance of the right temporal lobe when combining MRI(-) and MRI(+) TLE patients. Our data further point to an important role of the right mesial temporal region in face recognition in TLE.

Epilepsy, Temporal Lobe↗

PubMed1984

An investigation into component and configural processes underlying face perception.

The nature of the processes underlying face perception was examined in two different paradigms using the same set of stimuli varying on three dimensions of two values each. In a simultaneous matching task, both latencies and errors were found to decrease as the number of differences between stimuli increased. Regression analyses showed that the manipulated features interactively contributed to these variations when the faces were presented in their normal upright orientation, whereas no evidence of an interactive processing was found when the faces were inverted. A multidimensional scaling analysis of dissimilarity judgements between pairs of different upright faces revealed that the overall impression of a face was not simply the sum of subimpressions, and that a configuration typical of each face emerged from the relationship among their particular features, giving each face its individuality. The results suggest that faces have both component and configural properties and lend themselves to different processing strategies that are not mutually exclusive and can unfold simultaneously. Some implications of these results for current research on face perception and recognition are outlined.

Adult↗

PubMed1997

Putting faces to names.

An experiment is reported which investigated participants' ability to remember a person's face when they were presented with the person's name. During the learning phase, participants were shown 18 unfamiliar faces together with a name and occupation. At test, participants were presented with a name and were asked to indicate the face and occupation that had been presented with that name at learning. Results showed that participants' ability to remember the face was contingent upon their ability to remember the occupation that had been presented with the name. When participants were presented with a face and were asked to remember the name, performance was also contingent upon correctly remembering the associated occupation, consistent with the findings of McWeeny, Young, Hay & Ellis (1987). No such contingencies were apparent when participants were given an occupation and were asked to remember the associated name and face; participants frequently remembered the name but not the face, or the face without the name. These results are consistent with the serial access model of person identification proposed by Bruce & Young (1986), and with more recent developments proposed by Valentine, Brédart, Lawson & Ward (1991) and Craigie & Hanley (1993) in which there are no direct links between the representation of a person's name in memory and visual information about their facial appearance. The mnemonic strategies that were used by the participants during the learning phase of the experiment were also examined. These strategies help explain those few occasions on which participants appear to be able to link names to faces without identity-specific semantic information.

Adolescent↗

PubMed1993

The effect of bilateral cold block of the primate face primary somatosensory cortex on the performance of trained tongue-protrusion task and biting tasks.

1. Studies using ablation, intracortical microstimulation (ICMS) and surface stimulation, and single-neuron recordings have suggested that the primate primary somatosensory cortex (SI) may play an important role in movement control. Our aim was to determine whether bilateral inactivation of face SI would indeed interfere with the control of tongue or jaw-closing movements. 2. Effects of reversible inactivation by cooling of face SI was investigated in two monkeys trained to perform both a tongue-protrusion task and a biting task. The cooling experiments were carried out after the orofacial representation within SI was identified by systematically defining the mechanoreceptive field of single neurons recorded in face SI. The deficits in the tongue or jaw-closing movement were evaluated by the success rates for the monkeys' performance of both tasks and by the force and electromyographic (EMG) activity recorded from the masseter, genioglossus, and digastric muscles associated with the tasks. 3. During bilateral cooling of face SI, there was a statistically significant reduction in the success rates for the performance of the tongue-protrusion task in comparison with control series of trials while the thermodes used to cool face SI were kept at 37 degrees C. Detailed analyses of force and EMG activity showed that the principal deficit was the inability of the monkeys to maintain a steady tongue-protrusive force in the force holding period during each trial and to exert a consistent tongue-protrusion force between different trials. The task performance returned to control protocol levels at 4 min after commencement of rewarming. 4. Identical cooling conditions did not significantly affect the success rates for the performance of the biting task. Although the extent of the deficit was not severe enough to cause a significant reduction in successful rates for the biting task, cooling did significantly affect the ability of the monkeys to maintain a steady force in the holding period during each trial and to exert a consistent force between different trials. In one monkey the success rate of the biting task was also not affected by bilaterally cooling of face SI with a pair of larger thermodes placed on the dura over most of the face SI, face primary motor cortex (face MI), and adjacent cortical regions.(ABSTRACT TRUNCATED AT 400 WORDS)

Afferent Pathways↗

PubMed1994

Functional properties of single neurons in the primate face primary somatosensory cortex. III. Modulation of responses to peripheral stimuli during trained orofacial motor behaviors.

1. In previous papers we have demonstrated that most single neurons in the face primary somatosensory cortex (SI) alter their firing rate during a trained tongue-protrusion task and some also during a trained biting task. Although the data suggest that some of the task-related activity in face SI might conceivably come from reafferent inputs from moving orofacial structures, it is possible that orofacial inputs are modulated during the trained orofacial movements. This study was initiated to investigate the possible modulation of evoked orofacial somatosensory responses of face SI neurons during trained tongue-protrusion and biting tasks. 2. Two monkeys were trained to perform a tongue-protrusion and a biting task and to accept stimulation applied to the facial skin or the lingual nerve during the tasks. For SI neurons with a tongue mechanoreceptive field (RF), electrical stimulation was applied to the lingual nerve to elicit neuronal activity; for SI neurons with a RF at the other locations, electrical or mechanical stimulation was applied to the RF to elicit neuronal activity. Modulation of neuronal activity evoked by low-threshold stimulation of the RF was tested, during the tongue-protrusion and/or biting tasks, in 44 face SI neurons and an additional 3 forelimb SI neurons with a palm RF (palm RF neurons). The 44 face SI neurons included 13 with a tongue RF (tongue RF neurons), 29 with a lip RF (lip RF neurons), and 2 with a lateral face RF (face RF neurons). 3. For face SI neurons tested during both force dynamic and holding phases of the task period, the evoked activity (i.e., the number of evoked spikes in 50 ms after the onset of stimulation) was decreased in at least one of the two phases for the majority (90%) of 31 neurons studied during the tongue-protrusion task and 61% of 23 studied during the biting task. The proportion of neurons modulated during the tongue-protrusion task was significantly higher than that during the biting task. For the 18 face SI tested during both tasks, a decrease in evoked activity occurred in 10 lip RF neurons for both tasks and in the remaining 5 lip RF and 3 tongue RF neurons for the tongue-protrusion task only. No neurons tested showed a clear facilitation of evoked activity during the task period of either task.(ABSTRACT TRUNCATED AT 400 WORDS)

Afferent Pathways↗

PubMed1995

Face-sensitive regions in human extrastriate cortex studied by functional MRI.

1. We have previously identified face-selective areas in the mid-fusiform and inferior temporal gyri in electrophysiological recordings made from chronically implanted subdural electrodes in epilepsy patients. In this study, functional magnetic resonance imaging (fMRI) was used to study the anatomic extent of face-sensitive brain regions and to assess hemispheric laterality. 2. A time series of 128 gradient echo echoplanar images was acquired while subjects continuously viewed an alternating series of 10 unfamiliar faces followed by 10 equiluminant scrambled faces. Each cycle of this alternating sequence lasted 12 s and each experimental run consisted of 14 cycles. The time series of each voxel was transformed into the frequency domain using Fourier analysis. Activated voxels were defined by significant peaks in their power spectra at the frequency of stimulus alternation and by a 180 degrees phase shift that followed changes in stimulus alternation order. 3. Activated voxels to faces were obtained in the fusiform and inferior temporal gyri in 9 of 12 subjects and were approximately coextensive with previously identified face-selective regions. Nine subjects also showed activation in the left or right middle occipital gyri, or in the superior temporal or lateral occipital sulci. Cortical volumes activated in the left and right hemispheres were not significantly different. Activated voxels to scrambled faces were observed in six subjects at locations mainly in the lingual gyri and collateral sulci, medial to the regions activated by faces. 4. Face stimuli activated portions of the midfusiform and inferior temporal gyri, including adjacent cortex within occipitotemporal sulci.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed1998

Covert visual attention modulates face-specific activity in the human fusiform gyrus: fMRI study.

Several lines of evidence demonstrate that faces undergo specialized processing within the primate visual system. It has been claimed that dedicated modules for such biologically significant stimuli operate in a mandatory fashion whenever their triggering input is presented. However, the possible role of covert attention to the activating stimulus has never been examined for such cases. We used functional magnetic resonance imaging to test whether face-specific activity in the human fusiform face area (FFA) is modulated by covert attention. The FFA was first identified individually in each subject as the ventral occipitotemporal region that responded more strongly to visually presented faces than to other visual objects under passive central viewing. This then served as the region of interest within which attentional modulation was tested independently, using active tasks and a very different stimulus set. Subjects viewed brief displays each comprising two peripheral faces and two peripheral houses (all presented simultaneously). They performed a matching task on either the two faces or the two houses, while maintaining central fixation to equate retinal stimulation across tasks. Signal intensity was reliably stronger during face-matching than house matching in both right- and left-hemisphere predefined FFAs. These results show that face-specific fusiform activity is reduced when stimuli appear outside (vs. inside) the focus of attention. Despite the modular nature of the FFA (i.e., its functional specificity and anatomic localization), face processing in this region nonetheless depends on voluntary attention.

Adolescent↗

PubMed2003

Face-selective activation in a congenital prosopagnosic subject.

Congenital prosopagnosia is a severe impairment in face identification manifested from early childhood in the absence of any evident brain lesion. In this study, we used fMRI to compare the brain activity elicited by faces in a congenital prosopagnosic subject (YT) relative to a control group of 12 subjects in an attempt to shed more light on the nature of the brain mechanisms subserving face identification. The face-related activation pattern of YT in the ventral occipito-temporal cortex was similar to that observed in the control group on several parameters: anatomical location, activation profiles, and hemispheric laterality. In addition, using a modified vase-face illusion, we found that YT's brain activity in the face-related regions manifested global grouping processes. However, subtle differences in the degree of selectivity between objects and faces were observed in the lateral occipital cortex. These data suggest that face-related activation in the ventral occipito-temporal cortex, although necessary, might not be sufficient by itself for normal face identification.

Adult↗

PubMed2005

Structural encoding of body and face in human infants and adults.

Most studies on visual perception of human beings have focused on perception of faces. However, bodies are another important visual element, which help us to identify a member of our species in the visual scene. In order to study whether similar configural information processing is used in body and face perception, we recorded high-density even-related potentials (ERPs) to normal and distorted faces and bodies in adults and 3-month-old infants. In adults, the N1 responses evoked by bodies and faces were similar in amplitude but differed slightly in latency. The voltage topography of N1 also differed in concordance with fMRI data showing that two distinct areas are involved in face and body perception. Distortion affected ERPs to faces and bodies similarly from N1 on, although the effect was significant earlier for bodies than for faces. These results suggest that fast processing of configural information is not specific to faces but it also occurs for bodies. In 3-month-old infants, distortion decreased the amplitude of P400 around 450 msec, showing no interaction with image category. This result demonstrates that infants are not only able to recognize the normal configuration of faces, but also that of bodies. This could either be related to an innate knowledge of this particular type of biological object, or to fast learning through intense exposure during the first months of life.

Adult↗