Neural Face Processing Research Articles

Brain activity underlying face and face pareidolia processing: an ERP study.

Face pareidolia is described as an interpretation of any unrelated object seen for the first time as a face. It is still unclear how to face pareidolia is processed. In this study, the neural basis of face and face pareidolia processing was investigated through recording event-related potentials (ERPs). The ERPs were recorded from 35 right-handed and healthy participants in response to faces and face pareidolia. Amplitudes and latencies of N170, vertex-positive potential (VPP), and N250 components were analyzed, and current source density (CSD) maps relevant to these components were obtained. N170 response was earlier and larger in response to faces compared to face pareidolias. VPP is also evoked earlier in response to faces as in the case of N170; however, the VPP amplitude was larger for face pareidolias than for faces. Statistical analyses did not reveal any differences between faces and face pareidolias in terms of N250 component. The results indicated that faces and face pareidolias are processed in the early stages of visual perception. In addition, the N250 component does not reflect the neural processing of faces and face pareidolias.

Spatio-temporal dynamics of face perception

The temporal and spatial neural processing of faces has been investigated rigorously, but few studies have unified these dimensions to reveal the spatio-temporal dynamics postulated by the models of face processing. We used support vector machine decoding and representational similarity analysis to combine information from different locations (fMRI), time windows (EEG), and theoretical models. By correlating representational dissimilarity matrices (RDMs) derived from multiple pairwise classifications of neural responses to different facial expressions (neutral, happy, fearful, angry), we found early EEG time windows (starting around 130 ​ms) to match fMRI data from primary visual cortex (V1), and later time windows (starting around 190 ​ms) to match data from lateral occipital, fusiform face complex, and temporal-parietal-occipital junction (TPOJ). According to model comparisons, the EEG classification results were based more on low-level visual features than expression intensities or categories. In fMRI, the model comparisons revealed change along the processing hierarchy, from low-level visual feature coding in V1 to coding of intensity of expressions in the right TPOJ. The results highlight the importance of a multimodal approach for understanding the functional roles of different brain regions in face processing.

Own-race and other-race face recognition problems without visual expertise problems in dyslexic readers

Both intact and deficient neural processing of faces has been found in dyslexic readers. Similarly, behavioral studies have shown both normal and abnormal face processing in developmental dyslexia. We tested whether dyslexic adults are impaired in tests of own-race and other-race face recognition. As both face and word recognition rely considerably on visual expertise, we wished to investigate whether face recognition problems of dyslexic readers might stem from difficulties with experience-driven expert visual processing. We utilized the finding that people tend to be worse at discriminating other-race faces compared to own-race faces, the so-called other-race effect, thought to reflect greater experience with own-race faces. If visual expertise is compromised in dyslexic readers, so that their visual system is not effectively shaped by experience, then they might show a diminished other-race effect. Matched dyslexic and typical readers completed two tests of own- and other-race face recognition. The results show that dyslexic readers have problems with recognizing faces, and these difficulties are not fully accounted for by general problems with attention or memory. However, recognition is compromised for both own- and other-race faces, and the strength of the other-race effect does not differ between dyslexic and typical readers. There was individual variability in both groups, and an exploratory analysis revealed that while dyslexic readers with no university education showed deficits in face recognition, the dyslexic participants with higher education did not. We conclude that dyslexic readers as a group have face recognition problems. These are potentially modulated by educational level but compromised visual expertise cannot demonstrably account for the face recognition problems associated with dyslexia. We discuss the implications of these findings for theoretical accounts of dyslexia and for theories of word and face recognition.

An intergenerational family study on the impact of experienced and perpetrated child maltreatment on neural face processing

Altered processing of emotional faces due to childhood maltreatment has repeatedly been reported, and may be a key process underlying the intergenerational transmission of maltreatment. The current study is the first to examine the role of neural reactivity to emotional and neutral faces in the transmission of maltreatment, using a multi-generational family design including 171 participants of 51 families of two generations with a large age range (8–69 years). The impact of experienced and perpetrated maltreatment (abuse and neglect) on face processing was examined in association with activation in the amygdala, hippocampus, inferior frontal gyrus (IFG) and insula in response to angry, fearful, happy and neutral faces. Results showed enhanced bilateral amygdala activation in response to fearful faces in older neglected individuals, whereas reduced amygdala activation was found in response to these faces in younger neglected individuals. Furthermore, while experienced abuse was associated with lower IFG activation in younger individuals, experience of neglect was associated with higher IFG activation in this age group, pointing to potentially differential effects of abuse and neglect and significant age effects. Perpetrated abusive and neglectful behavior were not related to neural activation in any of these regions. Hence, no indications for a role of neural reactivity to emotional faces in the intergenerational transmission of maltreatment were found.

COMTVal158Met Genotype Affects Complex Emotion Recognition in Healthy Men and Women.

The catechol-o-methyltransferase (COMT) gene has repeatedly been shown to change amygdala activity and amygdala-prefrontal connectivity during face processing. Although the COMT gene appears to induce a negativity bias during the neural processing of faces, it is currently unclear whether a similar negativity bias emerges during the behavioral processing of faces. To address this issue, we investigated differences in complex emotion recognition between participants (n = 181) that had been a priori genotyped for functional polymorphisms of the COMT (Val158Met) and serotonin transporter (5-HTTLPR) gene. We were, thus, able to analyze differences in face processing on basis of participants’ COMT genotype while controlling for participants’ 5-HTTLPR genotype. Variations of participants’ COMT but not 5-HTTLPR genotype accounted for differences in participants’ emotion recognition performance: Met/Met carriers and Met/Val carriers were more accurate in the recognition of negative, but not neutral or positive, expressions than Val/Val carriers. We, therefore, revealed a similar negativity bias during the behavioral processing of faces that has already been demonstrated during the neural processing of faces, indicating that genotype-dependent changes in catecholamine metabolism may affect face processing on the behavioral and neural level.

Threat-conditioned contexts modulate the late positive potential to faces-A mobile EEG/virtual reality study.

In everyday life, the motivational value of faces is bound to the contexts in which faces are perceived. Electrophysiological studies have demonstrated that inherent negatively valent contexts modulate cortical face processing as assessed with ERP components. However, it is not well understood whether learned (rather than inherent) and three-dimensional aversive contexts similarly modulate the neural processing of faces. Using full immersive virtual reality (VR) and mobile EEG techniques, 25 participants underwent a differential fear conditioning paradigm, in which one virtual room was paired with an aversive noise burst (threat context) and another with a nonaversive noise burst (safe context). Subsequently, avatars with neutral or angry facial expressions were presented in the threat and safe contexts while EEG was recorded. Analysis of the late positive potential (LPP), which presumably indicates motivational salience, revealed a significant interaction of context (threat vs. safe) and face type (neutral vs. angry). Neutral faces evoked increased LPP amplitudes in threat versus safe contexts, while angry faces evoked increased early LPP amplitudes regardless of context. In addition to indicating that threat-conditioned contexts alter the processing of ambiguous faces, the present study demonstrates the successful integration of EEG and VR with particular relevance for affective neuroscience research.

Brain Activity Related to the Judgment of Face-Likeness: Correlation between EEG and Face-Like Evaluation.

Faces represent important information for social communication, because social information, such as face-color, expression, and gender, is obtained from faces. Therefore, individuals' tend to find faces unconsciously, even in objects. Why is face-likeness perceived in non-face objects? Previous event-related potential (ERP) studies showed that the P1 component (early visual processing), the N170 component (face detection), and the N250 component (personal detection) reflect the neural processing of faces. Inverted faces were reported to enhance the amplitude and delay the latency of P1 and N170. To investigate face-likeness processing in the brain, we explored the face-related components of the ERP through a face-like evaluation task using natural faces, cars, insects, and Arcimboldo paintings presented upright or inverted. We found a significant correlation between the inversion effect index and face-like scores in P1 in both hemispheres and in N170 in the right hemisphere. These results suggest that judgment of face-likeness occurs in a relatively early stage of face processing.

Changes in face-specific neural processing explain reduced cuteness and approachability of infants with cleft lip

ABSTRACTThe current study investigated whether changes in the neural processing of faces of infants with a facial abnormality – a cleft lip – mediate effects of the cleft lip on judgments of infant cuteness and approachability. Event-related potentials (ERPs) in response to pictures of faces of healthy infants and infants with a cleft lip, and ratings of cuteness and approachability of these infant faces, were obtained from 30 females. Infants with a cleft lip were rated as less attractive (less cute and approachable) than healthy infants, and both the N170 and P2 components of the ERP were of reduced amplitude in response to pictures of infants with a cleft lip. Importantly, decreased configural processing of infant faces with a cleft lip, as evidenced by reduced N170 amplitudes, mediated the reduced attractiveness ratings for infants with a cleft lip compared to healthy infants. Our findings help elucidate the mechanisms behind the less favorable responses to infants with a cleft lip, highlighting the role of face-specific rather than domain-general neural processes.

The light-makeup advantage in facial processing: Evidence from event-related potentials

The effects of makeup on attractiveness have been evaluated using mainly subjective measures. In this study, event-related brain potentials (ERPs) were recorded from a total of 45 Japanese women (n = 23 and n = 22 for Experiment 1 and 2, respectively) to examine the neural processing of faces with no makeup, light makeup, and heavy makeup. To have the participants look at each face carefully, an identity judgement task was used: they were asked to judge whether the two faces presented in succession were of the same person or not. The ERP waveforms in response to the first faces were analyzed. In two experiments with different stimulus probabilities, the amplitudes of N170 and vertex positive potential (VPP) were smaller for faces with light makeup than for faces with heavy makeup or no makeup. The P1 amplitude did not differ between facial types. In a subsequent rating phase, faces with light makeup were rated as more attractive than faces with heavy makeup and no makeup. The results suggest that the processing fluency of faces with light makeup is one of the reasons why light makeup is preferred to heavy makeup and no makeup in daily life.

Spatial Frequency Training Modulates Neural Face Processing: Learning Transfers from Low- to High-Level Visual Features.

Perception of visual stimuli improves with training, but improvements are specific for trained stimuli rendering the development of generic training programs challenging. It remains unknown to which extent training of low-level visual features transfers to high-level visual perception, and whether this is accompanied by neuroplastic changes. The current event-related potential (ERP) study showed that training-induced increased sensitivity to a low-level feature, namely low spatial frequency (LSF), alters neural processing of this feature in high-level visual stimuli. Specifically, neural activity related to face processing (N170), was decreased for low (trained) but not high (untrained) SF content in faces following LSF training. These novel results suggest that: (1) SF discrimination learning transfers from simple stimuli to complex objects; and that (2) training the use of specific SF information affects neural processing of facial information. These findings may open up a new avenue to improve face recognition skills in individuals with atypical SF processing, such as in cataract or Autism Spectrum Disorder (ASD).

The special status of sad infant faces: age and valence differences in adults' cortical face processing.

Understanding the relative and joint prioritization of age- and valence-related face characteristics in adults’ cortical face processing remains elusive because these two characteristics have not been manipulated in a single study of neural face processing. We used electroencephalography to investigate adults’ P1, N170, P2 and LPP responses to infant and adult faces with happy and sad facial expressions. Viewing infant vs adult faces was associated with significantly larger P1, N170, P2 and LPP responses, with hemisphere and/or participant gender moderating this effect in select cases. Sad faces were associated with significantly larger N170 responses than happy faces. Sad infant faces were associated with significantly larger N170 responses in the right hemisphere than all other combinations of face age and face valence characteristics. We discuss the relative and joint neural prioritization of infant face characteristics and negative facial affect, and their biological value as distinct caregiving and social cues.

Face processing in adolescents with positive and negative threat bias.

Individuals with anxiety disorders exhibit a 'vigilance-avoidance' pattern of attention to threatening stimuli when threatening and neutral stimuli are presented simultaneously, a phenomenon referred to as 'threat bias'. Modifying threat bias through cognitive retraining during adolescence reduces symptoms of anxiety, and so elucidating neural mechanisms of threat bias during adolescence is of high importance. We explored neural mechanisms by testing whether threat bias in adolescents is associated with generalized or threat-specific differences in the neural processing of faces. Subjects were categorized into those with (n = 25) and without (n = 27) threat avoidance based on a dot-probe task at average age 12.9 years. Threat avoidance in this cohort has previously been shown to index threat bias. Brain response to individually presented angry and neutral faces was assessed in a separate session using functional magnetic resonance imaging. Adolescents with threat avoidance exhibited lower activity for both angry and neutral faces relative to controls in several regions in the occipital, parietal, and temporal lobes involved in early visual and facial processing. Results generalized to happy, sad, and fearful faces. Adolescents with a prior history of depression and/or an anxiety disorder had lower activity for all faces in these same regions. A subset of results replicated in an independent dataset. Threat bias is associated with generalized, rather than threat-specific, differences in the neural processing of faces in adolescents. Findings may aid in the development of novel treatments for anxiety disorders that use attention training to modify threat bias.

Hippocampal Brain Volume Is Associated with Faster Facial Emotion Identification in Older Adults: Preliminary Results.

Quick correct identification of facial emotions is highly relevant for successful social interactions. Research suggests that older, compared to young, adults experience increased difficulty with face and emotion processing skills. While functional neuroimaging studies suggest age differences in neural processing of faces and emotions, evidence about age-associated structural brain changes and their involvement in face and emotion processing is scarce. Using structural magnetic resonance imaging (MRI), this study investigated the extent to which volumes of frontal and temporal brain structures were related to reaction time in accurate identification of facial emotions in 30 young and 30 older adults. Volumetric segmentation was performed using FreeSurfer and gray matter volumes from frontal and temporal regions were extracted. Analysis of covariances (ANCOVAs) models with response time (RT) as the dependent variable and age group and regional volume, and their interaction, as independent variables were conducted, controlling for total intracranial volume (ICV). Results indicated that, in older adults, larger hippocampal volumes were associated with faster correct facial emotion identification. These preliminary observations suggest that greater volume in brain regions associated with face and emotion processing contributes to improved facial emotion identification performance in aging.

The time course of individual face recognition: A pattern analysis of ERP signals

An extensive body of work documents the time course of neural face processing in the human visual cortex. However, the majority of this work has focused on specific temporal landmarks, such as N170 and N250 components, derived through univariate analyses of EEG data. Here, we take on a broader evaluation of ERP signals related to individual face recognition as we attempt to move beyond the leading theoretical and methodological framework through the application of pattern analysis to ERP data. Specifically, we investigate the spatiotemporal profile of identity recognition across variation in emotional expression. To this end, we apply pattern classification to ERP signals both in time, for any single electrode, and in space, across multiple electrodes. Our results confirm the significance of traditional ERP components in face processing. At the same time though, they support the idea that the temporal profile of face recognition is incompletely described by such components. First, we show that signals associated with different facial identities can be discriminated from each other outside the scope of these components, as early as 70ms following stimulus presentation. Next, electrodes associated with traditional ERP components as well as, critically, those not associated with such components are shown to contribute information to stimulus discriminability. And last, the levels of ERP-based pattern discrimination are found to correlate with recognition accuracy across subjects confirming the relevance of these methods for bridging brain and behavior data. Altogether, the current results shed new light on the fine-grained time course of neural face processing and showcase the value of novel methods for pattern analysis to investigating fundamental aspects of visual recognition.

Measuring the face-sensitive N170 with a gaming EEG system: A validation study

BackgroundThe N170 is a “face-sensitive” event-related potential (ERP) that occurs at around 170ms over occipito-temporal brain regions. The N170's potential to provide insight into the neural processing of faces in certain populations (e.g., children and adults with cognitive impairments) is limited by its measurement in scientific laboratories that can appear threatening to some people. New methodThe advent of cheap, easy-to-use portable gaming EEG systems provides an opportunity to record EEG in new contexts and populations. This study tested the validity of the face-sensitive N170 ERP measured with an adapted commercial EEG system (the Emotiv EPOC) that is used at home by gamers. ResultsThe N170 recorded through both the gaming EEG system and the research EEG system exhibited face-sensitivity, with larger mean amplitudes in response to the face stimuli than the non-face stimuli, and a delayed N170 peak in response to face inversion. Comparison with existing methodThe EPOC system produced very similar N170 ERPs to a research-grade Neuroscan system, and was capable of recording face-sensitivity in the N170, validating its use as research tool in this arena. ConclusionsThis opens new possibilities for measuring the face-sensitive N170 ERP in people who cannot travel to a traditional ERP laboratory (e.g., elderly people in care), who cannot tolerate laboratory conditions (e.g., people with autism), or who need to be tested in situ for practical or experimental reasons (e.g., children in schools)

Neural Correlates of Face Familiarity in Institutionally Reared Children With Distinctive, Atypical Social Behavior.

Although the impact of early adverse experience on neural processing of face familiarity has been studied, research has not taken into account disordered child behavior. This work compared the neural processing of familiar versus strangers' faces in 47 institutionalized children with a mean age of 54months to determine the effects of (a) the presence versus absence of atypical social behavior and (b) inhibited versus indiscriminant atypical behavior. Results revealed a pattern of cortical hypoactivation in institutionalized children manifesting atypical social behavior and that inhibited children displayed larger neural response to a caregiver's face than to the stranger's, while indiscriminant children did not discriminate between stimuli. These findings suggest that neural correlates of face familiarity are associated with social functioning in institutionalized children.

Differential Early Processing for Faces and Characters: N170 Inversion and Mirror Effects

In the current study we compared the inversion and mirror effects on the N170 component, an event-related potential related to the neural processing of faces, in Chinese characters and faces. Faces displayed an obvious inversion effect on N170 latency and amplitude, whereas characters only showed a slight inversion effect on N170 latency. Moreover, both faces and characters were tolerant to mirror reversal for the N170 component despite a robust behavioral mirror cost for characters. These data indicate dissociation between processing faces and characters during the early perceptual stage.

Situation-based social anxiety enhances the neural processing of faces: evidence from an intergroup context.

Social anxiety is the intense fear of negative evaluation by others, and it emerges uniquely from a social situation. Given its social origin, we asked whether an anxiety-inducing social situation could enhance the processing of faces linked to the situational threat. While past research has focused on how individual differences in social anxiety relate to face processing, we tested the effect of manipulated social anxiety in the context of anxiety about appearing racially prejudiced in front of a peer. Visual processing of faces was indexed by the N170 component of the event-related potential. Participants viewed faces of Black and White males, along with nonfaces, either in private or while being monitored by the experimenter for signs of prejudice in a 'public' condition. Results revealed a difference in the N170 response to Black and Whites faces that emerged only in the public condition and only among participants high in dispositional social anxiety. These results provide new evidence that anxiety arising from the social situation modulates the earliest stages of face processing in a way that is specific to a social threat, and they shed new light on how anxiety effects on perception may contribute to the regulation of intergroup responses.

Neural processing of high and low spatial frequency information in faces changes across development: qualitative changes in face processing during adolescence

Face perception in adults depends on skilled processing of interattribute distances ('configural' processing), which is disrupted for faces presented in inverted orientation (face inversion effect or FIE). Children are not proficient in configural processing, and this might relate to an underlying immaturity to use facial information in low spatial frequency (SF) ranges, which capture the coarse information needed for configural processing. We hypothesized that during adolescence a shift from use of high to low SF information takes place. Therefore, we studied the influence of SF content on neural face processing in groups of children (9-10years), adolescents (14-15years) and young adults (21-29years) by measuring event-related potentials (ERPs) to upright and inverted faces which varied in SF content. Results revealed that children show a neural FIE in early processing stages (i.e. P1; generated in early visual areas), suggesting a superficial, global facial analysis. In contrast, ERPs of adults revealed an FIE at later processing stages (i.e. N170; generated in face-selective, higher visual areas). Interestingly, adolescents showed FIEs in both processing stages, suggesting a hybrid developmental stage. Furthermore, adolescents and adults showed FIEs for stimuli containing low SF information, whereas such effects were driven by both low and high SF information in children. These results indicate that face processing has a protracted maturational course into adolescence, and is dependent on changes in SF processing. During adolescence, sensitivity to configural cues is developed, which aids the fast and holistic processing that is so special for faces.

Direct Gaze Elicits Atypical Activation of the Theory-of-Mind Network in Autism Spectrum Conditions

Eye contact plays a key role in social interaction and is frequently reported to be atypical in individuals with autism spectrum conditions (ASCs). Despite the importance of direct gaze, previous functional magnetic resonance imaging in ASC has generally focused on paradigms using averted gaze. The current study sought to determine the neural processing of faces displaying direct and averted gaze in 18 males with ASC and 23 matched controls. Controls showed an increased response to direct gaze in brain areas implicated in theory-of-mind and gaze perception, including medial prefrontal cortex, temporoparietal junction, posterior superior temporal sulcus region, and amygdala. In contrast, the same regions showed an increased response to averted gaze in individuals with an ASC. This difference was confirmed by a significant gaze direction × group interaction. Relative to controls, participants with ASC also showed reduced functional connectivity between these regions. We suggest that, in the typical brain, perceiving another person gazing directly at you triggers spontaneous attributions of mental states (e.g. he is “interested” in me), and that such mental state attributions to direct gaze may be reduced or absent in the autistic brain.