Face recognition in preschool children: effects of familiarity, facial expression and angle of view]

The purpose of this study was to investigate the face recognition processes in preschool children. Two experiments were carried out to examine the effects, on face recognition, of familiarity, facial expression and angle of view of faces as well as changes or no changes in facial expression and/or angle of view occurring between the first presentation and the subsequent recognition test. The subjects were 188 five- and six-year old children. In Experiments 1 and 2, half of the faces were highly familiar to the subjects, and the remaining half unfamiliar to them. In Experiment 1, the facial expressions (e.g., smiling or serious) were either changed or unchanged. In Experiment 2, the facial expressions or angles of view (e.g., full-face views or three-quarter views of faces) were either changed or unchanged. The major findings were that the familiar faces and the smiling faces were recognized more correctly than the unfamiliar faces and the serious faces respectively. The results were discussed in terms of 'identity-specific semantic codes' and 'visually-derived semantic codes'.     

Face recognition failures in schizotypy

Introduction. Existing eye-tracking literature has shown that both adults and children with autism spectrum disorders (ASD) show fewer and slower fixations on faces. Despite this reduced saliency and processing of other faces, recognition of their own face is reported to be more “typical” in nature. This study uses eye-tracking to explore the typicality of gaze patterns when children with ASD attend their own faces compared to other familiar and unfamiliar faces.

Methods. Eye-tracking methodology was used to explore fixation duration and time taken to fixate on the Eye and Mouth regions of familiar, unfamiliar and Self Faces. Twenty-one children with ASD (9–16 years) were compared to typically developing matched groups.

Results. There were no significant differences between children with ASD and typically matched groups for fixation patterns to the Eye and Mouth areas of all face types (familiar, unfamiliar and self). Correlational analyses showed that attention to the Eye area of unfamiliar and Self Faces was related to socio-communicative ability in children with ASD.

Conclusions. Levels of socio-communicative ability in children with ASD were related to gaze patterns on unfamiliar and Self Faces, but not familiar faces. This lack of relationship between ability and attention to familiar faces may indicate that children across the autism spectrum are able to fixate these faces in a similar way. The implications for these findings are discussed.     

The effect of learning on the face selective responses of neurons in the cortex in the superior temporal sulcus of the monkey

Summary Neurophysiological studies have shown that some neurons in the cortex in the superior temporal sulcus and the inferior temporal gyrus of macaque monkeys respond to faces. These neurons provided a consistently identifiable substrate with which studies of the storage of visual information were performed. To determine whether face responsive neurons change how much they respond to different novel faces as they become familiar, neurons were tested with two experimental designs. In the first experiment, 22 neurons were tested on their responsiveness to the different members of a large set of novel faces as the set was presented repeatedly until the faces became familiar. 6 neurons altered the relative degree to which they responded to the different members of the set between the first two presentations and subsequent presentations. In a control condition, only 1 out of 17 neurons showed a significant response difference between the first two presentations and subsequent presentations when the experiment started with faces which were already familiar to the monkey. In the second experiment, 26 neurons were tested on their responsiveness to the different members of a set of familiar faces before and after the addition of a novel face to the set. 5 neurons altered the relative degree in which they responded to the different members of the set of familiar faces after addition of a novel face. It is suggested that these changes in neuronal responsiveness to different stimuli reflect the setting up of an ensemble encoded representation of face stimuli. This alteration of neuronal responsiveness as novel faces become familiar suggests that face responsive neurons may store information useful in visual recognition.In addition to this relatively long-term alteration of relative neuronal responsiveness to different stimuli, it was found that a large number of cells showed a higher mean response to the first presentation of a set of novel faces than to subsequent presentations of the faces. However, the response to the first presentation of a set of familiar faces was also higher than to subsequent presentations in that sequence. This pattern indicates a short term recency effect in the response of these neurons to visual stimuli which is similar to that previously reported (Baylis and Rolls 1987).     

The role of long-term and short-term familiarity in visual and haptic face recognition

Recent studies have suggested that the familiarity of a face leads to more robust recognition, at least within the visual domain. The aim of our study was to investigate whether face familiarity resulted in a representation of faces that was easily shared across the sensory modalities. In Experiment 1, we tested whether haptic recognition of a highly familiar face (one's own face) was as efficient as visual recognition. Our observers were unable to recognise their own face models from tactile memory alone but were able to recognise their faces visually. However, haptic recognition improved when participants were primed by their own live face. In Experiment 2, we found that short-term familiarisation with a set of previously unfamiliar face stimuli improved crossmodal recognition relative to the recognition of unfamiliar faces. Our findings suggest that familiarisation provides a strong representation of faces but that the nature of the information encoded during learning is critical for efficient crossmodal recognition.     

The effects of inversion and eye displacements of familiar and unknown faces on early and late-stage ERPs.

OBJECTIVES: The objective of this study is to examine whether configural alterations of faces affect early or late processing stages as a function of their familiarity and their level of representation in memory. We then sought to verify whether the structural encoding stage is susceptible to top-down influences. METHODS: Electrophysiologic and behavioral studies were undertaken, during which unknown and familiar faces were presented upright or upside-down with or without feature alterations. The subjects were asked to determine whether the faces were familiar or not. RESULTS: N170 and N360 amplitudes were larger for familiar faces as well as altered ones. A higher degree of familiarity decreased reaction times (RTs) and N360 latencies, but increased N170 latencies, whereas face alterations increased RTs and latencies of both components examined. However, familiarity interacted with altered face configurations only for RTs and the N170. SIGNIFICANCE: In the perceptual stage, familiar faces seem to develop a more elaborate type of processing because of top-down influences linked to the robust nature of their representations in memory. The more elaborate type of processing for familiar faces has advantageous consequences for the following steps of information processing, by facilitating access to structural representations in memory (N360) as well as the final step reflected by RTs. The fact that configural alterations cause different effects for familiar as opposed to unfamiliar faces indicate that these stimuli are processed in a qualitatively different manner and solicit different representations in memory.     

Structural encoding and identification in face processing: erp evidence for separate mechanisms

The present study had two aims. The first aim was to explore the possible top-down effect of face-recognition and/or face-identification processes on the formation of structural representation of faces, as indexed by the N170 ERP component. The second aim was to examine possible ERP manifestations of face identification processes as an initial step for assessing their time course and functional neuroanatomy. Identical N170 potentials were elicited by famous and unfamiliar faces in Experiment 1, when both were irrelevant to the task, suggesting that face familiarity does not affect structural encoding processes. Small but significant differences were observed, however, during later-occurring epochs of the ERPs. In Experiment 2 the participants were instructed to count occasionally occurring portraits of famous politicians while rejecting faces of famous people who were not politicians and faces of unfamiliar people. Although an attempt to identify each face was required, no differences were found in the N170 elicited by faces of unfamiliar people and faces of familiar non-politicians. Famous faces, however, elicited a negative potential that was significantly larger than that elicited by unfamiliar faces between about 250 and 500msec from stimulus onset. This negative component was tentatively identified as an N400 analogue elicited by faces. Both the absence of an effect of familiarity on the N170 and the familiarity face-N400 effect were replicated in Experiment 3, in which the participants made speeded button-press responses in each trial, distinguishing among faces of politicians and faces of famous and unfamiliar non-politicians. In addition, ERP components later than the N400 were found to be associated with the speed of the response but not with face familiarity. We concluded that (1) although reflected by the N170, the structural encoding mechanism is not influenced by the face recognition and identification processes, and (2) the negative component modulated by face familiarity is associated with the semantic activity involved in the identification of familiar faces.     

STRUCTURAL ENCODING AND IDENTIFICATION IN FACE PROCESSING: ERP EVIDENCE FOR SEPARATE MECHANISMS

The present study had two aims. The first aim was to explore the possible top-down effect of face-recognition and/or face-identification processes on the formation of structural representation of faces, as indexed by the N170 ERP component. The second aim was to examine possible ERP manifestations of face identification processes as an initial step for assessing their time course and functional neuroanatomy. Identical N170 potentials were elicited by famous and unfamiliar faces in Experiment 1, when both were irrelevant to the task, suggesting that face familiarity does not affect structural encoding processes. Small but significant differences were observed, however, during later-occurring epochs of the ERPs. In Experiment 2 the participants were instructed to count occasionally occurring portraits of famous politicians while rejecting faces of famous people who were not politicians and faces of unfamiliar people. Although an attempt to identify each face was required, no differences were found in the N170 elicited by faces of unfamiliar people and faces of familiar non-politicians. Famous faces, however, elicited a negative potential that was significantly larger than that elicited by unfamiliar faces between about 250 and 500msec from stimulus onset. This negative component was tentatively identified as an N400 analogue elicited by faces. Both the absence of an effect of familiarity on the N170 and the familiarity face-N400 effect were replicated in Experiment 3, in which the participants made speeded button-press responses in each trial, distinguishing among faces of politicians and faces of famous and unfamiliar non-politicians. In addition, ERP components later than the N400 were found to be associated with the speed of the response but not with face familiarity. We concluded that (1) although reflected by the N170, the structural encoding mechanism is not influenced by the face recognition and identification processes, and (2) the negative component modulated by face familiarity is associated with the semantic activity involved in the identification of familiar faces.     

Face recognition without awareness

PH has been completely unable to recognise faces since sustaining a closed head injury some four years ago, but can recognise familiar people from their names. His performance on face processing tasks is, however, comparable to that of normal subjects if explicit recognition is not required. Thus he can make same/different identity judgements more quickly for familiar than unfamiliar face photographs, and faster matching of familiar faces is only found for identity matches involving the face's internal features. When making semantic categorisation decisions to printed names he shows interference from distractor faces belonging to an incorrect category, even when the faces in each category are matched on physical appearance. When learning to associate the occupation or the name with photographs of faces, his performance is better with true (face and person's actual name or occupation) than untrue (face and another person's name or occupation) pairings. Covert recognition can also be demonstrated for faces of people PH has only met since his accident. These findings show that in prosopagnosia, much of the processing of familiar faces can remain intact despite absence of awareness that recognition has occurred.     

What's special about personally familiar faces? A multimodal approach

Dual-route models of face recognition suggest separate cognitive and affective routes. The predictions of these models were assessed in recognition tasks with unfamiliar, famous, and personally familiar faces. Whereas larger autonomic responses were only triggered for personally familiar faces, priming effects in reaction times to these faces, presumably reflecting cognitive recognition processes, were equal to those of famous faces. Activation of stored structural representations of familiar faces (face recognition units) was assessed by recording the N250r component in event-related brain potentials. Face recognition unit activation increased from unfamiliar over famous to personally familiar faces, suggesting that there are stronger representations for personally familiar than for famous faces. Because the topographies of the N250r for personally and famous faces were indistinguishable, a similar network of face recognition units can be assumed for both types of faces.     

Interaction of facial expressions and familiarity: ERP evidence

There is mounting evidence that under some conditions the processing of facial identity and facial emotional expressions may not be independent; however, the nature of this interaction remains to be established. By using event-related brain potentials (ERP) we attempted to localize these interactions within the information processing system. During an expression discrimination task (Experiment 1) categorization was faster for portraits of personally familiar vs. unfamiliar persons displaying happiness. The peak latency of the P300 (trend) and the onset of the stimulus-locked LRP were shorter for familiar than unfamiliar faces. This implies a late perceptual but pre-motoric locus of the facilitating effect of familiarity on expression categorization. In Experiment 2 participants performed familiarity decisions about portraits expressing different emotions. Results revealed an advantage of happiness over disgust specifically for familiar faces. The facilitation was localized in the response selection stage as suggested by a shorter onset of the LRP. Both experiments indicate that familiarity and facial expression may not be independent processes. However, depending on the kind of decision different processing stages may be facilitated for happy familiar faces.     

Automatic without autonomic responses to familiar faces: Differential components of covert face recognition in a case of Capgras delusion

Introduction. This study was designed to elucidate the relationship between different types of covert face recognition. Some patients with prosopagnosia (i.e., the profound inability to recognise previously familiar faces) nonetheless evince autonomic face recognition (elevated skin-conductance levels to familiar faces) or behavioural indices of covert recognition (i.e., priming; interference effects; matching effects; face-name learning). One prosopagnosic patient revealed both autonomic and behavioural covert face recognition-which suggests they may arise from some common basis. Method. To test this claim a patient with the Capgras delusion (i.e., holding the belief that others have been replaced by impostors, etc.) was tested on each type of covert face recognition and her results compared with agematched controls. We know that the Capgras delusion is characterised by good overt or conscious face recognition coupled with the absence of autonomic discrimination between familiar and unfamiliar faces. The question addressed here was whether, compared with age- and gender-matched controls, the patient, B.P., would show neither autonomic nor behavioural covert face recognition. Results. The answer was that, although she showed no autonomic discrimination, her performance on a priming task and a test of face/name interference were normal. The controls, as expected, revealed covert face recognition on both the autonomic and behavioural measures. Conclusions. The results imply in B.P. a clear dissociation between autonomic and behavioural measures of covert face recognition. The theoretical implications of these results are discussed.     

The effects of identity of facial expression and person on face recognition: a study using priming paradigm

Three experiments investigated the effects of identity of facial expression and person of two successively presented faces on face recognition. In each experiment, a combination of a familiar/unfamiliar person with neutral/smile expression was presented. Four different groups of 8 or 12 undergraduates were asked to judge the facial expression or the familiarity of the second face. The results showed that reaction times in both judgments were shorter when the same person repeatedly appeared than when two different people were presented. This repetition effect was not affected by facial expression of the stimulus for expression judgments, while it depended on the expression and familiarity of the first and second faces for familiarity judgments. In facial expression judgments, reaction times to smile faces were shorter than those to the neutral faces, only when subjects were familiar with those faces. This facial expression effect appeared only when the identical familiar and smile person was repeatedly presented for familiarity judgments. These results suggested the interdependency between analysis of facial expression and that of person information in face recognition processes.     

Neuronal correlates of repetition priming of frequently presented objects: insights from induced gamma band responses

The activation of cortical object representations requires the integration of dispersed cortical areas, signified by induced oscillatory bursts of activity > 20 Hz (induced Gamma Band Responses; iGBRs) at approximately 300 ms after stimulus onset. A well established marker of the functional dynamics within such cell assemblies is the suppression of iGBR amplitudes after the repetition of familiar stimuli. This effect is commonly interpreted as a signature of 'sharpening' processes within conceptual networks, which are behaviourally mirrored in repetition priming effects. Furthermore, it was demonstrated that the repetition of unfamiliar stimuli leads to iGBR increases indicating the 'formation' of a new cell assembly. A limitation of previous experiments was that only small numbers of repetitions were used. Thus, in the present EEG study we presented familiar and unfamiliar stimuli 10 times. We were able to replicate sharpening effects within conceptual networks representing familiar stimuli. Furthermore, we observed a gradual increase of iGBRs elicited by repeated unfamiliar stimuli. Interestingly, this formation effect did not turn into a sharpening effect after many repetitions (i.e. after an unfamiliar stimulus became familiar). Thus, we conclude that sharpening and formation effects rely on qualitatively different networks representing familiar and unfamiliar material.     

Differentiated Brain Activity in Response to Faces of “Own” Versus “Unfamiliar” Babies in Primipara Mothers: An Electrophysiological Study

Experiences with one's own infant attune the parent nervous system to infant stimuli. To explore the effects of motherhood on brain activity patterns, electroencephalogram (EEG) was recorded while primipara mothers of 3- and 6-month-olds viewed images of faces of their own child and an unfamiliar but appearance-matched child. Mothers of 3- and 6-month-olds showed equivalent early-wave (N/P1 “visual” and N170 “face-sensitive”) responses to own and unfamiliar baby faces but differentiating late-wave (N/P600 “familiar/?novel”) activity to own versus unfamiliar infant faces. Based on 3 months experience with their own infant's face, mothers' brain patterns give evidence of distinctive late-wave (recognition) sensitivity.     

Neural Correlates of Familiar and Unfamiliar Face Processing in Infants at Risk for Autism Spectrum Disorders

Examining the neural correlates associated with processing social stimuli offers a viable option to the challenge of studying early social processing in infants at risk for autism spectrum disorders (ASDs). The present investigation included 32 12-month olds at high risk for ASD and 24 low-risk control infants, defined on the basis of family history. Infants were presented with familiar and unfamiliar faces, and three components of interest were explored for amplitude and latency differences. The anticipated developmental effects of emerging hemispheric asymmetry for face-sensitive components (the N290 and P400) were observed, as were familiarity effects for a component related to attention (the Nc). Although there were no striking group differences in the neural response to faces, there was some evidence for a developmental lag in an attentional component for the high-risk group. The infant ASD endophenotype, though elusive, may be better defined through expanding the age of study and addressing change over time in response to varied stimuli.     

Detecting a viewer’s familiarity with a face: Evidence from event-related brain potentials and classifier analyses

Human observers recognize the faces of people they know efficiently and without apparent effort. Consequently, recognizing a familiar face is often assumed to be an automatic process beyond voluntary control. However, there are circumstances in which a person might seek to hide their recognition of a particular face. The present study therefore used event-related potentials (ERPs) and a classifier based on logistic regression to determine if it is possible to detect whether a viewer is familiar with a particular face, regardless of whether the participant is willing to acknowledge it or not. In three experiments, participants were presented with highly variable “ambient” images of personally familiar and unfamiliar faces, while performing an incidental butterfly detection task (Experiment 1), an explicit familiarity judgment task (Experiment 2), and a concealed familiarity task in which they were asked to deny familiarity with one truly known facial identity while acknowledging familiarity with a second known identity (Experiment 3). In all three experiments, we observed substantially more negative ERP amplitudes at occipito-temporal electrodes for familiar relative to unfamiliar faces starting approximately 200 ms after stimulus onset. Both the earlier N250 familiarity effect, reflecting visual recognition of a known face, and the later sustained familiarity effect, reflecting the integration of visual with additional identity-specific information, were similar across experiments and thus independent of task demands. These results were further supported by the classifier analysis. We conclude that ERP correlates of familiar face recognition are largely independent of voluntary control and discuss potential applications in forensic settings.     

Racial distinction of the unknown facial identity recognition mechanism by event-related fMRI

A body of evidence exists indicating that the function of the fusiform area of the face is selectively involved in the perception of faces, and in particular, in perceiving racial differences. In the present study, we investigated the neural substrates of the face-selective region (the fusiform face area, FFA) in the ventral occipital-temporal cortex and examined their role in case of same-racial face recognition by employing event-related fMRI. Twelve healthy subjects (Oriental-Koreans) performed the familiarity judgment tasks while they were being presented with familiar and unknown faces of Oriental-Koreans and Caucasian-Americans. The results indicate that there are significant differences in perceiving unfamiliar faces between Oriental-Koreans and Caucasian-Americans in the FFA, whereas no significant difference was found between familiar Oriental-Korean and Caucasian-American faces in the same area. This suggests that an effect of same-race superiority exists when the perceived identity is only unfamiliar. The neural responses to Oriental-Koreans versus Caucasian-Americans in Oriental-Korean subjects likely reflect cultural evaluations of social groups as modified by individual experience.     

An electrophysiological index of stimulus unfamiliarity

This study investigated the functional significance of the N2 response to novel stimuli. In one condition, background, target, and deviant stimuli were simple geometric figures. In a second condition, all stimulus types were unfamiliar/unusual figures. In a third condition, background and target stimuli were unusual figures and deviant stimuli were simple shapes. Unusual figures, whether they were deviant, target, or background stimuli, evoked larger N2 responses than their simple, familiar counterparts. N2 elicited by an unusual background stimulus was larger than that evoked by simple, deviant stimuli, a pattern opposite that exhibited by the subsequent P3. Deviance from immediate context had limited influence over N2 amplitude. The results suggest that novelty N2 and novelty P3 reflect the processing of different aspects of "novel" visual stimuli. The novelty P3 is particularly sensitive to deviation from immediate context. In contrast, the novelty N2 is sensitive to deviation from long-term context that renders a stimulus unfamiliar and difficult to encode.     

Wired for Her Face? Male Attentional Bias for Female Faces

Under conditions of inattention or deficits in orienting attention, special classes of stimuli (e.g. faces, bodies) are more likely to be perceived than other stimuli. This suggests that biologically salient visual stimuli automatically recruit attention, even when they are task-irrelevant or ignored. Here we report results from a behavioral experiment with female and male subjects and two magnetoencephalography (MEG) experiments with male subjects only, in which we investigated attentional capture with face and hand stimuli. In both the behavioral and MEG experiments, subjects were required to count the number of gender-specific targets from either face or hand categories within a block of stimuli. In the behavioral experiment, we found that male subjects were significantly more accurate in response to female than male face target blocks. There was no corresponding effect found in response to hand target blocks. Female subjects did not show a gender-based difference in response to face or hand target blocks. MEG results indicated that the male subjects’ responses to face stimuli in primary visual cortex (V1) and the face-selective part of the fusiform gyrus (FG) were reduced when male face stimuli were not relevant to the task, whereas female faces maintained a strong response in these areas in both task-relevant and task-irrelevant conditions. These results suggest that within the male brain, female face stimuli are more resilient to suppression than male faces, once attention is drawn to the part of the visual field where the face appears.     

Memory-related ERP components for experimentally learned faces and names: characteristics and parallel-test reliabilities

Previous research with preexperimentally familiar faces and names has identified several memory-related components in the event-related potential (ERP). Here we aimed to characterize these components while controlling the quality of long-term memory with a standardized learning procedure for unfamiliar faces and names. After 1 week, recognition was tested in a repetition priming paradigm. Both early repetition effects (ERE/N250r) and old/new effects had very similar time course and domain-related scalp topographies as has been reported for preexperimentally familiar stimuli. The late repetition effects (LRE/N400) showed domain-specific scalp topographies, possibly reflecting the greater ease of deriving semantic codes from faces. Importantly, parallel-test reliabilities of performance and memory-related ERP components were high, thus demonstrating the utility of face learning for formal assessment procedures in person recognition.