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PubMed1994

Event-related potentials to faces: the effects of priming and recognition.

Short-term visual memory, as in both implicit priming and explicit recognition tasks, can be demonstrated by decreased reaction times, the ability to preferentially select previously presented objects from lists and the ability to more readily complete previously exposed words from fragmented letters. The visual processing of faces occurs separately from the visual processing of non-face stimuli, within discrete areas of bilateral posterior inferotemporal cortices. While visual recognition and memory of faces are independent of those for non-faces, their processing appears to be similar. We have demonstrated an electrophysiologic correlate of short-term visual memory in a face-matching paradigm. We have observed a series of evoked potential components consisting predominantly of a C140, C180 and C240 with a posterior, bitemporal distribution. The priming effect is reflected by a diminution of C240 amplitude in the response to repeated pictures of faces compared to novel pictures of faces. These data reflect a previously unreported set of neurophysiological observations on short-term visual memory for faces.

Adult↗
PubMed1990

Order of feature recognition in familiar and unfamiliar faces.

Three experiments measured order of processing for single faces presented to the left or right visual field (VF) using a same-different matching task. In contrast to earlier studies, the stimuli in the present experiments were carefully matched for overall similarity prior to the actual experiments. Experiments 1 and 2 showed that a significant top-to-bottom order of processing occurred for line drawings of unfamiliar faces but not for line drawings of familiar faces. Experiment 3 found evidence supporting top-to-bottom processing for unfamiliar photographic face stimuli. The photographic stimuli in Experiment 3 were matched more quickly when presented in the left VF (right hemisphere); however, this VF asymmetry was not related to previously reported differences in order of processing. It is suggested that under some conditions faces presented to the right hemisphere may be processed more like familiar faces than faces presented to the left hemisphere; however, this difference is not critical for the left VF (right hemisphere) superiority often found in face recognition tasks.

Adult↗
PubMed2004

Association between vertical development of the cervical spine and the face in subjects with varying vertical facial patterns.

The upper cervical spine and face were compared longitudinally from 6 to 15 years of age in 2 groups of children with low (n = 16) and high (n = 14) MP-SN angles. The purpose of the study was to assess morphological and incremental associations between the vertical development of the cervical spine and the face in subjects with varying vertical facial patterns. Morphological associations were not detected during the observation period. Long faces were found on children with short necks, and short, square faces on those with long necks. Vertical growth of the upper cervical spine and face were weakly correlated in the 6-to-12-year period but strongly correlated later during puberty. The vertical distance between gonion and the body of the second cervical vertebra was remarkable for its constancy during childhood and puberty, indicating that gonion and the second cervical vertebra body were anatomically interrelated. This anatomical relationship strongly suggests that a mutual relationship also exists between vertical growth of the upper cervical spine and the face, especially the lower face. In addition, the lower face had the ability for independent vertical growth that was not coordinated with vertical cervical growth. This was the case in the 6-to-12-year period, but not later.

Adolescent↗
PubMed2006

What aspects of face processing are impaired in developmental prosopagnosia?

Developmental prosopagnosia (DP) is a severe impairment in identifying faces that is present from early in life and that occurs despite no apparent brain damage and intact visual and intellectual function. Here, we investigated what aspects of face processing are impaired/spared in developmental prosopagnosia by examining a relatively large group of individuals with DP (n = 8) using an extensive battery of well-established tasks. The tasks included measures of sensitivity to global motion and to global form, detection that a stimulus is a face, determination of its sex, holistic face processing, processing of face identity based on features, contour, and the spacing of features, and judgments of attractiveness. The DP cases showed normal sensitivity to global motion and global form and performed normally on our tests of face detection and holistic processing. On the other tasks, many DP cases were impaired but there was no systematic pattern. At least half showed deficits in processing of facial identity based on either the outer contour or spacing of the internal features, and/or on judgments of attractiveness. Three of the eight were impaired in processing facial identify based on the shape of internal features. The results show that DP is a heterogeneous condition and that impairment in recognizing faces cannot be predicted by poor performance on any one measure of face processing.

Adult↗
PubMed2006

Psychophysiological correlates of face processing in social phobia.

Social phobia has been associated with abnormal processing of angry faces, which directly signal disapproval--a situation that social phobics fear. This study investigated the electrophysiological correlates of emotional face processing in socially phobic and non-phobic individuals. Subjects identified either the gender (modified emotional Stroop task) or the expression of angry, happy, or neutral faces. Social phobics showed no deviations from controls in reaction times, heart rates, P1, or P2 amplitudes in response to angry faces, although elevated FSS scores were associated with higher P1 amplitudes in social phobic persons. In addition, social phobic persons showed enhanced right temporo-parietal N170 amplitudes in response to angry faces in the emotion identification task. Furthermore, higher scores on the Social Phobia and Anxiety Inventory (SPAI) were associated as a trend with larger N170 amplitudes in response to angry faces in the emotion identification task. Thus, the present results suggest that social phobics show abnormalities in the early visual processing of angry faces, as reflected by the enhanced right-hemispheric N170 when the emotion of the angry face was the focus of attention, while behavioral responses and heart rates showed no evidence for preferred processing of angry facial expressions.

Adult↗
PubMed2004

Familiar-face recognition and comparison: source analysis of scalp-recorded event-related potentials.

OBJECTIVE: We studied the event-related potentials elicited by categorical matching of faces. The purpose was to find cortical sources responsible for face recognition and comparison. METHODS: Nineteen healthy volunteers participated in the study. Each trial began with one of the two cues (S1) followed by consecutive pictures (S2 and S3). Each picture was a photograph of a familiar face with a superimposed abstract dot pattern. One cue directed attention to compare faces and another to compare patterns. 128-channel electroencephalogram was recorded. Spatio-temporal multiple dipole source models were generated using Brain Electromagnetic Source Analysis 2000, for the window of 80-600 ms from S3 onset. RESULTS: The obtained model for face recognition and comparison contained 8 dipoles explaining 97% of grand average and about 90% of individual data and showing temporal and spatial separation of sources: in the frontal region, in the occipital cortex, and in the bilateral medial temporal and inferotemporal regions. Different faces elicited larger components than same person's faces around 400 ms, mainly explained by frontal dipoles. CONCLUSIONS: The sources in our models estimate the activity common for both Face task conditions (the recognition of a familiar person) and also differential activity, related to the match/mismatch item processing.

Adult↗
PubMed2005

Hemispheric metacontrol and cerebral dominance in healthy individuals investigated by means of chimeric faces.

Cerebral dominance and hemispheric metacontrol were investigated by testing the ability of healthy participants to match chimeric, entire, or half faces presented tachistoscopically. The two hemi-faces compounding chimeric or entire stimuli were presented simultaneously or asynchronously at different exposure times. Participants did not consciously detect chimeric faces for simultaneous presentations lasting up to 40 ms. Interestingly, a 20 ms separation between each half-chimera was sufficient to induce detection of conflicts at a conscious level. Although the presence of chimeric faces was not consciously perceived, performance on chimeric faces was poorer than on entire- and half-faces stimuli, thus indicating an implicit processing of perceptual conflicts. Moreover, the precedence of hemispheric stimulation over-ruled the right hemisphere dominance for face processing, insofar as the hemisphere stimulated last appeared to influence the response. This dynamic reversal of cerebral dominance, however, was not caused by a shift in hemispheric specialization, since the level of performance always reflected the right hemisphere specialization for face recognition. Thus, the dissociation between hemispheric dominance and specialization found in the present study hints at the existence of hemispheric metacontrol in healthy individuals.

Adult↗
PubMed2005

Strength of visual percept generated by famous faces perceived without awareness: effects of affective valence, response latency, and visual field.

Participants who were unable to detect familiarity from masked 17 ms faces (Stone and Valentine, 2004 and Stone and Valentine, in press-b) did report a vague, partial visual percept. Two experiments investigated the relative strength of the visual percept generated by famous and unfamiliar faces, using masked 17 ms exposure. Each trial presented simultaneously a famous and an unfamiliar face, one face in LVF and the other in RVF. In one task, participants responded according to which of the faces generated the stronger visual percept, and in the other task, they attempted an explicit familiarity decision. The relative strength of the visual percept of the famous face compared to the unfamiliar face was moderated by response latency and participants' attitude towards the famous person. There was also an interaction of visual field with response latency, suggesting that the right hemisphere can generate a visual percept differentiating famous from unfamiliar faces more rapidly than the left hemisphere. Participants were at chance in the explicit familiarity decision, confirming the absence of awareness of facial familiarity.

Adult↗
PubMed2004

Scale invariant adaptation in fusiform face-responsive regions.

Several functional neuroimaging studies have observed response adaptation in face-sensitive regions when repeating identical face stimuli. To address whether this was due to low-level stimulus properties or facial identity, we decomposed pictures of faces into pictures preserving only the lower or higher parts of the normal frequency spectrum. In an event-related functional neuroimaging study, pairs of such pictures were sequentially presented that showed the same or different persons in the same or different frequency bands. This factorial design allowed to separate effects related to repetition of personal identity from those related to identical stimulus properties. In a random effects group analysis, activation in the right fusiform region was affected by repetition of personal identity regardless of changing or constant spatial scale. Responses in the more medial and posterior fusiform and lingual regions adapted with repetition of the same frequency band. An analysis in regions of interest determined individually as face responsive showed that repetition decreases for the same faces in fusiform face-responsive regions generalized across spatial frequency bands. Our results therefore point to a role of this area in discriminating individual faces at a level of representation that is invariant to changes in low-level stimulus properties, as spatial scale. The same invariance could not be detected in more posterior occipital face-responsive regions.

Adaptation, Physiological↗
PubMed2005

fMRI activity in the medial temporal lobe during famous face processing.

The current event-related fMRI study examined the relative involvement of different parts of the medial temporal lobe (MTL), particularly the contribution of hippocampus and perirhinal cortex, in either intentional or incidental recognition of famous faces in contrast to unfamiliar faces. Our intention was to further explore the controversial contribution of MTL in the processing of semantic memory tasks. Subjects viewed a sequence of famous and unfamiliar faces. Two tasks were used encouraging attention to either fame or gender. In the fame task, the subjects were requested to identify the person when seeing his/her face and also to try to generate the name of this person. In the gender task, the subjects were asked to conduct a judgement of a person's gender when seeing his/her face. The visual processing was hence directed to gender and thereby expected to diminish attention to semantic information leading only to a "passive" registration of famous and non-familiar faces. Recognition of famous faces, in both contrasts, produced significant activations in the MTL. First, during the intentional recognition (the person identification task) increased activity was observed in the anterolateral part of left hippocampus, in proximity to amygdala. Second, during the incidental recognition of famous faces (the gender classification task), there was increased activity in the left posterior MTL with focus in the perirhinal cortex. Our results suggest that the hippocampus may be centrally involved in the intentional retrieval of semantic memories while the perirhinal cortex is associated with the incidental recognition of semantic information.

Adult↗
PubMed2005

Are the perceptual biases found in chimeric face processing reflected in eye-movement patterns?

Studies of patients with focal brain lesions and neuroimaging indicate that face processing is predominantly based on right hemisphere function. Additionally, experiments using chimeric faces, where the left and the right-hand side of the face are different, have shown that observers tend to bias their responses toward the information on the left. Here, we monitored eye-movements during a gender identification task using blended face images for both whole and chimeric (half female, half male) faces [Neuropsychologia 35 (1997) 685]. As expected, we found a left perceptual bias: subjects based their gender decision significantly more frequently on the left side of the chimeric faces. Analysis of the first saccade showed a significantly greater number of left fixations independent of perceptual bias presumably reflecting the tendency to first inspect the side of the face better suited to face analysis (left side of face/right hemisphere). On top of this though, there was a relationship between response and fixation pattern. On trials where participants showed a left perceptual bias they produced significantly more left saccades and fixated for longer on the left. In contrast, for trials where participants showed a right perceptual bias there was no reliable difference between the number, or total fixation duration, on the left or the right. These results demonstrate that on a trial-by-trial basis subtle differences in the extent of left or right side scanning are related to the perceptual response of the participant, although an overall initial fixation bias to the left occurs irrespective of response bias.

Adult↗
PubMed2005

Progressive N170 habituation to unattended repeated faces.

This study utilized a location-matching task to investigate whether the face-sensitive N170 event-related potential component would habituate in its response to the repeated presentation of same face stimuli when face identity was irrelevant to the experimental task. N170 amplitude decreased progressively with repeated presentation of the same face vs. sequential presentation of novel faces. This N170 habituation to face identity repetition occurred only for faces at unattended spatial locations, likely representing a relatively pure observation of automatic early face processing.

Adolescent↗
PubMed2005

Orientation tuning of human face processing estimated by contrast matching in transparency displays.

Upright images of faces appear more salient than faces of other orientations. We exploited this effect in a titration experiment where faces were superimposed in transparency. By manipulating the physical contrast of the component images, we measured the degree of perceptual dominance as function of the orientation of the face in the image plane. From these measurements, we obtain the orientation tuning of face processing, which is well approximated by a Gaussian function with a SD of about 45 deg and mean centered on upright. Faces predominantly lit from above and from below produced very similar results. However, when presented with scrambled faces observers showed no orientation preference. We argue that these results can be explained by the existence of specialized face processing mechanisms with an orientation tuning with a bandwidth of approximately 90 deg, predominantly centered on the upright orientation and easily disrupted by alterations of the normal facial configuration.

Contrast Sensitivity↗
PubMed2006

Flash-lag chimeras: the role of perceived alignment in the composite face effect.

Spatial alignment of different face halves results in a configuration that mars the recognition of the identity of either face half (). What would happen to the recognition performance for face halves that were aligned on the retina but were perceived as misaligned, or were misaligned on the retina but were perceived as aligned? We used the 'flash-lag' effect () to address these questions. We created chimeras consisting of a stationary top half-face initially aligned with a moving bottom half-face. Flash-lag chimeras were better recognized than their stationary counterparts. However when flashed face halves were presented physically ahead of moving halves thereby nulling the flash-lag effect, recognition was impaired. This counters the notion that relative movement between the two face halves per se is sufficient to explain better recognition of flash-lag chimeras. Thus, the perceived spatial alignment of face halves (despite retinal misalignment) impairs recognition, while perceived misalignment (despite retinal alignment) does not.

Face↗
PubMed2006

Representations of familiar and unfamiliar faces as revealed by viewpoint-aftereffects.

A viewpoint-dependent aftereffect occurs after prolonged viewing of a stimulus of a particular orientation, with the result that the test image is perceived to be facing away from the adapting orientation. Prior psychophysical work has led to the suggestion that the visual brain encodes a limited range of viewpoint information with regard to complex images. In this study, we investigated whether familiar faces were susceptible to a viewpoint aftereffect. Familiar faces are believed to be represented in a view-invariant manner, whereas unfamiliar faces are represented in a viewpoint-dependent manner. Adaptation to both familiar and unfamiliar faces influenced the perception of viewpoint of subsequent face images. However, category-specific transfer of a repulsive viewpoint-dependent aftereffect was observed with unfamiliar faces. Our results suggest that neural networks that mediate viewpoint information are also involved in view-invariant representation of familiar faces.

Adult↗
PubMed2004

Face and facial expression memory in temporal lobe epilepsy patients: preliminary results.

Right temporal lobe structures are involved in face and facial expression processing and in mnestic functions. Face and facial expression memory was investigated in 15 patients with left (LTLE) and 18 patients with right (RTLE) temporal lobe epilepsy as well as 13 healthy controls. Pairs of pictures combining four faces and four emotions had to be matched according to face identity or facial expression. In the memory tasks, the two pictures of a pair were divided by a memory interval of 2000 milliseconds, whereas in the perception tasks (control condition) both pictures were presented simultaneously. RTLE patients had significantly lower scores than healthy controls in face memory. LTLE patients had significantly lower scores than healthy controls in face and facial expression memory. The data confirm impaired face memory in RTLE patients and show that LTLE patients display deficits in face as well as in facial expression memory. Results are discussed according to functional reorganization, memory strategies, perception performance, naming problems, and group characteristics.

Adult↗
PubMed2006

Sex differences in face recognition memory in patients with temporal lobe epilepsy, patients with generalized epilepsy, and healthy controls.

The influence of sex on face recognition memory was studied in 49 patients with temporal lobe epilepsy, 20 patients with generalized epilepsy, and 32 healthy controls. After learning 20 faces, serially presented for 5 seconds each, subjects had to recognize the 20 among 40 faces (including 20 new faces) immediately and 24 hours later. Women had better face recognition than men, with no significant differences between groups. Women's advantage was due mainly to superior delayed recognition. Taken together, the results suggest that sex has a similar impact on face recognition in patients with epilepsy and healthy controls, and that testing delayed face recognition raises sensitivity for sex differences. The influence of sex on face recognition in patients with epilepsy should be acknowledged when evaluating individuals or comparing groups.

Adult↗
PubMed2003

Can holistic processing be learned for inverted faces?

The origin of "special" processing for upright faces has been a matter of ongoing debate. If it is due to generic expertise, as opposed to having some innate component, holistic processing should be learnable for stimuli other than upright faces. Here we assess inverted faces. We trained subjects to discriminate identical twins using up to 1100 exposures to each twin in different poses and images. In the upright orientation, twin discrimination was supported by holistic processing. Removal of a single face feature had no effect on performance, and a composite effect (Young, A. W., Hellawell, D., & Hay, D.C. (1987). Configurational information in face perception. Perception 16 (6), 747-759) was obtained. In the inverted orientation, however, above chance identification ability relied on (a) image specific learning, or (b) tiny local feature differences not noticed in the upright faces. The failure to learn holistic processing for inverted faces indicates that, in contrast to the situation for objects (Tarr, M.J., & Pinker, S. (1989). Mental rotation and orientation-dependence in shape recognition. Cognitive Psychology 21 (2), 233-282), orientation specificity of face processing is highly stable against practice.

Adolescent↗