Mechanisms Of Face Perception Research Articles

Real-life relevant face perception is not captured by the N170 but reflected in later potentials: A comparison of 2D and virtual reality stimuli.

The perception of faces is one of the most specialized visual processes in the human brain and has been investigated by means of the early event-related potential component N170. However, face perception has mostly been studied in the conventional laboratory, i.e., monitor setups, offering rather distal presentation of faces as planar 2D-images. Increasing spatial proximity through Virtual Reality (VR) allows to present 3D, real-life-sized persons at personal distance to participants, thus creating a feeling of social involvement and adding a self-relevant value to the presented faces. The present study compared the perception of persons under conventional laboratory conditions (PC) with realistic conditions in VR. Paralleling standard designs, pictures of unknown persons and standard control images were presented in a PC- and a VR-modality. To investigate how the mechanisms of face perception differ under realistic conditions from those under conventional laboratory conditions, the typical face-specific N170 and subsequent components were analyzed in both modalities. Consistent with previous laboratory research, the N170 lost discriminatory power when translated to realistic conditions, as it only discriminated faces and controls under laboratory conditions. Most interestingly, analysis of the later component [230-420 ms] revealed more differentiated face-specific processing in VR, as indicated by distinctive, stimulus-specific topographies. Complemented by source analysis, the results on later latencies show that face-specific neural mechanisms are applied only under realistic conditions (A video abstract is available in the Supplementary material and via YouTube: https://youtu.be/TF8wiPUrpSY).

ВОСПРИЯТИЕ СИММЕТРИЧНОСТИ ПРАВИЛЬНО ОРИЕНТИРОВАННОГО И ИНВЕРТИРОВАННОГО ЛИЦА

Background. X e uniqueness of human face perception mechanisms and their variability has become a subject for extensive investigation and wide discussion in the recent decades. While now the concept that human face is perceived as a whole is taken as a fact, the same cannot be said about the structure and methods to measure holistic processing. In the present study the factor of symmetry is investigated as one of the possible aspects of conW gural processing of facial perception. Objective. X e aim of the study was to apply the inversion method to the investigation of how distortion of facial conW guration perception impacts the rating of its symmetry/asymmetry Sample. 54 participants (24 female and 30 male) aged 18 to 68 (mean age 26) took part in the study. Method. An intra-individual experimental design was used. Participants rated asymmetry of normally oriented and inverted face-stimuli on a W ve-point scale. To set the symmetry level, leY eye and/or mouth regions were rotated around their W ducial points, there were three rotation angles for each feature region. Zero asymmetry faces were created by blending halves of normal and mirror images of the sample face-stimulus. X e mean asymmetry subjective ratings were submitted to repeated measures analysis of variance and paired samples t-test. Results. X e study revealed signiW cant diZ erences in the asymmetry ratings of upright and inverted faces: normal upright faces with rotated features were rated as more asymmetric compared to inverted. X us, we may conclude that symmetry perception is aZ ected by inversion. It was also revealed, that the eZ ect of the eye region and the lips region rotation were not equivalent: the higher the level rotation of the eye area was the more signiW cant the diZ erence between the rates of upright and inverted faces was, while rotation of the lips area did not result in higher diZ erence between the rates. Conclusion.X e observed face-inversion eZ ect in the perception of symmetry in facial stimuli suggests that (a)symmetry is a component of holistic (conW gurative) processing of human face perception. At the same time, the contributions of individual features to the overall facial conW guration may diZ er.

WildLab: A naturalistic free viewing experiment reveals previously unknown electroencephalography signatures of face processing.

Neural mechanisms of face perception are predominantly studied in well-controlled experimental settings that involve random stimulus sequences and fixed eye positions. Although powerful, the employed paradigms are far from what constitutes natural vision. Here, we demonstrate the feasibility of ecologically more valid experimental paradigms using natural viewing behaviour, by combining a free viewing paradigm on natural scenes, free of photographer bias, with advanced data processing techniques that correct for overlap effects and co-varying non-linear dependencies of multiple eye movement parameters. We validate this approach by replicating classic N170 effects in neural responses, triggered by fixation onsets (fixation event-related potentials [fERPs]). Importantly, besides finding a strong correlation between both experiments, our more natural stimulus paradigm yielded smaller variability between subjects than the classic setup. Moving beyond classic temporal and spatial effect locations, our experiment furthermore revealed previously unknown signatures of face processing: This includes category-specific modulation of the event-related potential (ERP)'s amplitude even before fixation onset, as well as adaptation effects across subsequent fixations depending on their history.

That person is now with or without\xa0a\xa0mask: how encoding context modulates identity recognition

Previous research has mostly approached face recognition and target identification by focusing on face perception mechanisms, but memory mechanisms also appear to play a role. Here, we examined how the presence of a mask interferes with the memory mechanisms involved in face recognition, focusing on the dynamic interplay between encoding and recognition processes. We approach two known memory effects: (a) matching study and test conditions effects (i.e., by presenting masked and/or unmasked faces) and (b) testing expectation effects (i.e., knowing in advance that a mask could be put on or taken off). Across three experiments using a yes/no recognition paradigm, the presence of a mask was orthogonally manipulated at the study and the test phases. All data showed no evidence of matching effects. In Experiment 1, the presence of masks either at study or test impaired the correct identification of a target. But in Experiments 2 and 3, in which the presence of masks at study or test was manipulated within participants, only masks presented at test-only impaired face identification. In these conditions, test expectations led participants to use similar encoding strategies to process masked and unmasked faces. Across all studies, participants were more liberal (i.e., used a more lenient criterion) when identifying masked faces presented at the test. We discuss these results and propose that to better understand how people may identify a face wearing a mask, researchers should take into account that memory is an active process of discrimination, in which expectations regarding test conditions may induce an encoding strategy that enables overcoming perceptual deficits.

The involvement of monocular channels in the face pareidolia effect.

Studies examining the neural mechanisms of face perception in humans have mainly focused on cortical networks of face-selective regions. However, subcortical regions are known to play a significant role in face perception as well. For instance, upon presenting pairs of faces sequentially to the same eye or to different eyes, superior performance is observed in the former condition. This superiority was explained by monocular, pre-striate processing of face stimuli. One of the intriguing face-related effects is the face pareidolia phenomenon, wherein observers perceive faces in inanimate objects. In this study, we examined whether face pareidolia involves similar low-level neural substrates to those that are involved in face perception. We presented participants with pairs of houses or face-like houses using a stereoscope to manipulate the information presented to each eye and asked them to determine whether the stimuli were similar or different. We managed to examine the contribution of monocular channels (mostly subcortical) in processing face-like stimuli. We hypothesized that besides their involvement in actual face perception, subcortical structures are engaged in face pareidolia as well. To test our hypothesis, we conducted three experiments to replicate and strengthen the reliability of our results and rule out alternative explanations. We demonstrated a perceptual benefit when presenting similar face-like houses to the same eye in comparison to their presentation to different eyes. This finding matches previous results found for images of real faces and indicates subcortical involvement not only in face perception but also in processing face-like objects.

Brain connectivity measures for holistic mechanisms of face perception

Brain connectivity measures for holistic mechanisms of face perception

Speaker Abstracts Plenary Lectures (PL) PL1. Face Perception in Infants Using Near-Infrared Spectroscopy (NIRS)

We have been studying the underlying mechanisms of face perception in humans using magneto-(MEG), electroencephalography (EEG) and near-infrared spectroscopy (NIRS). In this lecture, I will mainly focus on the development of face perception in infants. NIRS is a spectroscopic method using the near-infrared region of the electromagnetic spectrum (from 780 nm to 2500 nm). The biggest advantages of NIRS compared with functional magnetic resonance imaging (fMRI) are as follows: (1) NIRS can be used when subjects are moving, for example, during walking and cooking. Therefore, NIRS can be used to measure brain activity of infants and children who cannot help moving; (2) It is much cheaper. We recently made a special light probe of NIRS for studying infants. I will mainly introduce our basic studies of face perception in infants using NIRS. In addition, I will introduce our latest clinical studies in patients with attention deficit hyperactivity disorder (ADHD) and anorexia nervosa.

К ВОПРОСУ ОБ ОСОБЕННОСТЯХ АНАЛИЗА ДВИЖЕНИЙ ГЛАЗ В ПРОЦЕССЕ ВОСПРИЯТИЯ ЛИЦ

Background. The article is devoted to the study of the mechanisms of face perception when using the technology of eye-tracking. In the scientific literature, two processes are distinguished - analytical (perception of individual facial features) and holistic (perception of a general configuration of facial features). It is assumed that each of the mechanisms can be specifically manifested in patterns of eye movements during face perception. However, there is disagreement among the authors concerning the eye movements patterns which reflect the dominance of the holistic or analytic processing. We hypothesized that the contradictions in the interpretation of eye movement indicators in the studies of face perception may be associated with the features of the eye-tracker data processing, namely, with the specifics of identifying areas of interest (eyes, nose, bridge of the nose, lips), as well as with individual strategies of eye movements. Objective. Revealing the features of eye movements analysis in the process of facial perception. Method. A method for studying analytical and holistic processing in the task of assessing the attractiveness of upright and inverted faces using eye-tracking technology has been developed and tested. The eye-tracking data were analyzed for the entire sample using three types of processing, differing in the marking of the areas of interest (AOIs), and separately for two groups differing in eye movement strategies. The distinction of strategies was considered based on differences in the mean values of the fixation duration and the amplitude of saccades. Results. It was shown that: the presence of statistically significant differences of the dwell time in the AOIs between the condition of upright and inverted faces depended on the method of identifying these AOIs. It was shown that the distribution of the dwell time by zones is closely related to individual strategies of eye movements. Analysis of the data separately by groups showed significant differences in the distribution of the dwell time in the AOIs. Conclusion. When processing eye-tracking data obtained in the studies of face perception, it is necessary to consider individual strategies of eye movements, as well as the features associated with identifying AOIs. The absence of a single standard for identifying these areas can be the reason for inconsistency of the data about the holistic or analytical processing dominance. According to our data, the most effective for the analysis of holistic processing is a more detailed type of marking the AOIs, in which not only the main features (eyes, nose, mouth) are distinguished, but also the area of the nose bridge and nose.

Do intoxicated witnesses produce poor facial composite images?

RationaleThe effect of alcohol intoxication on witness memory and performance has been the subject of research for some time, however, whether intoxication affects facial composite construction has not been investigated.ObjectivesIntoxication was predicted to adversely affect facial composite construction.MethodsThirty-two participants were allocated to one of four beverage conditions consisting of factorial combinations of alcohol or placebo at face encoding, and later construction. Participants viewed a video of a target person and constructed a composite of this target the following day. The resulting images were presented as a full face composite, or a part face consisting of either internal or external facial features to a second sample of participants who provided likeness ratings as a measure of facial composite quality.ResultsIntoxication at face encoding had a detrimental impact on the quality of facial composites produced the following day, suggesting that alcohol impaired the encoding of the target faces. The common finding that external compared to internal features are more accurately represented was demonstrated, even following alcohol at encoding. This finding was moderated by alcohol and target face gender such that alcohol at face encoding resulted in reduced likeness of external features for male composite faces only.ConclusionsModerate alcohol intoxication impairs the quality of facial composites, adding to existing literature demonstrating little effect of alcohol on line-up studies. The impact of intoxication on face perception mechanisms, and the apparent narrowing of processing to external face areas such as hair, is discussed in the context of alcohol myopia theory.

Very small faces are easily discriminated under long and short exposure times.

Acuity measures related to overall face size that can be perceived have not been studied quantitatively. Consequently, experimenters use a wide range of sizes (usually large) without always providing a rationale for their choices. I studied thresholds for face discrimination by presenting both long (500 ms)- and short (17, 33, 50 ms)-duration stimuli. Face width threshold for the long presentation was ~0.2°, and thresholds for the flashed stimuli ranged from ~0.3° for the 17-ms flash to ~0.23° for the 33- and 50-ms flashes. Such thresholds indicate that face stimuli used in physiological or psychophysical experiments are often too large to tap human fine spatial capabilities, and thus interpretations of such experiments should take into account face discrimination acuity. The 0.2° threshold found in this study is incompatible with the prevalent view that faces are represented by a population of specialized "face cells" because those cells do not respond to <1° stimuli and are optimally tuned to >4° faces. Also, the ability to discriminate small, high-spatial frequency flashed face stimuli is inconsistent with models suggesting that fixational drift transforms retinal spatial patterns into a temporal code. It seems therefore that the small image motions occurring during fixation do not disrupt our perception, because all relevant processing is over with before those motions can have significant effects. NEW & NOTEWORTHY Although face perception is central to human behavior, the minimally perceived face size is not known. This study shows that humans can discriminate very small (~0.2°) faces. Furthermore, even when flashed for tens of milliseconds, ~0.25° faces can be discriminated. Such fine acuity should impact modeling of physiological mechanisms of face perception. The ability to discriminate flashed faces where there is almost no eye movement indicates that eye drift is not essential for visibility.

Attitudes about race predict individual differences in face adaptation aftereffects

This study examined whether category boundaries between Black and White faces relate to individual attitudes about race. Fifty-seven (20 Black, 37 White) participants completed measures of explicit racism, implicit racism, collective self-esteem (CSE), and racial centrality. Category boundaries between Black and White faces were measured in three separate conditions: following adaptation to (1) a neutral gray background, a sequence of (2) Black or (3) White faces. Two additional conditions measured category boundaries for facial distortion to investigate whether attitudes relate to mechanisms of racial identity alone, or to more global mechanisms of face perception. Using a two-alternative forced-choice staircase procedure, participants indicated whether a test image appeared to be Black or White (or contracted or expanded). Following neutral adaptation, participants with higher CSE showed category boundaries shifted toward faces with a higher percentage of Black features. In addition, the strength of short-term sensitivity shifts following adaptation to Black and White faces was related to explicit and implicit attitudes about race. Sensitivity shifts were weaker when participants scored higher on explicit racism, but were stronger when participants scored higher on implicit but lower on explicit racism. The results of this study indicate that attitudes about race account for some individual differences in natural category boundaries between races as well as the strength of identity aftereffects following face adaptation.

Neural mechanisms of face perception, their emergence over development, and their breakdown

Face perception is probably the most developed visual perceptual skill in humans, most likely as a result of its unique evolutionary and social significance. Much recent research has converged to identify a host of relevant psychological mechanisms that support face recognition. In parallel, there has been substantial progress in uncovering the neural mechanisms that mediate rapid and accurate face perception, with specific emphasis on a broadly distributed neural circuit, comprised of multiple nodes whose joint activity supports face perception. This article focuses specifically on the neural underpinnings of face recognition, and reviews recent structural and functional imaging studies that elucidate the neural basis of this ability. In addition, the article covers some of the recent investigations that characterize the emergence of the neural basis of face recognition over the course of development, and explores the relationship between these changes and increasing behavioural competence. This paper also describes studies that characterize the nature of the breakdown of face recognition in individuals who are impaired in face recognition, either as a result of brain damage acquired at some point or as a result of the failure to master face recognition over the course of development. Finally, information regarding similarities between the neural circuits for face perception in humans and in nonhuman primates is briefly covered, as is the contribution of subcortical regions to face perception. WIREs Cogn Sci 2016, 7:247-263. doi: 10.1002/wcs.1388 For further resources related to this article, please visit the WIREs website.

Что исследования работы мозга позволили узнать о восприятии лица человека и его экспрессий

The models of face perception mechanisms have been substantially extended recently by the results obtained with functional brain mapping studies. The current paper reviews the studies that help to define more precisely the functional organization of the distributed facial system. We explore the issue of independence versus interrelation of face identification and expression recognition; compare the mechanisms of static and dynamic faces perception, as well as face-in-context perception. We emphasize the importance of higher ecological validity of face perception and its brain mechanisms.

How distinct is the coding of face identity and expression? Evidence for some common dimensions in face space

Traditional models of face perception emphasize distinct routes for processing face identity and expression. These models have been highly influential in guiding neural and behavioural research on the mechanisms of face perception. However, it is becoming clear that specialised brain areas for coding identity and expression may respond to both attributes and that identity and expression perception can interact. Here we use perceptual aftereffects to demonstrate the existence of dimensions in perceptual face space that code both identity and expression, further challenging the traditional view. Specifically, we find a significant positive association between face identity aftereffects and expression aftereffects, which dissociates from other face (gaze) and non-face (tilt) aftereffects. Importantly, individual variation in the adaptive calibration of these common dimensions significantly predicts ability to recognize both identity and expression. These results highlight the role of common dimensions in our ability to recognize identity and expression, and show why the high-level visual processing of these attributes is not entirely distinct.

Transfer of figural face aftereffects suggests mature orientation selectivity in 8-year-olds’ face coding

Adult face perception mechanisms are tuned to upright faces, and this orientation selectivity is central to adult expertise with upright faces. Children are less expert than adults, and it has been argued that their face mechanisms are less orientation selective than those of adults. Here we used face aftereffects to test this hypothesis by examining whether children’s aftereffects show greater transfer across changes in orientation than do adults’ aftereffects. We adapted 7- to 8-year-old children and adults to figural face distortions in both upright and inverted orientations and examined the size of resulting aftereffects in both upright and inverted test faces. If children’s face mechanisms are less orientation selective than those of adults, then children’s aftereffects should transfer more strongly across changes in orientation. We found no evidence to support this prediction. Children’s and adults’ aftereffects were similarly reduced by orientation differences between adapt and test. These results indicate that children, like adults, show a high degree of orientation selectivity in face shape coding and suggest that neural tuning to face orientation may be mature by 8years of age. Our findings are consistent with an emerging view that many of the key attributes of specialized face perception emerge much earlier in development than previously thought.

An Eye-tracking Research on Featural, Configural and Holistic Processing Strategies in Face Perception

There were two main hypotheses attempting to explain the mechanisms of face perception. One was the holistic approach which claimed that faces were stored as relatively undifferentiated wholes, without explicitly representing the facial parts. The other was the dual-code view which claimed that faces were processed on the basis of featural and configural information and that the respective representations were stored in isolation. Indeed, neither of the two approaches could provide a detailed explanation of the mechanisms of face perception. Therefore integrated approaches were proposed. The present study in favor of these integrated systems aims at exploring featural, configural and holistic strategies during face perception. The presence of different eye movement patterns would imply how important information is extracted from facial stimuli. In the two experiments we explored the scanning behavior during face perception. In experiment 1, modified faces with primarily featural(scrambled faces) or configural(blurred faces) information were used as cue stimuli so as to manipulate the way participants processed intact faces which were presented soon afterwards. In a series of matching-to-sample tasks, participants decided whether the identity of an intact test face matched a precedent scrambled or blurred cue face. Analysis of eye movements for test faces showed more interfeatural saccades when preceded by blurred faces, and longer gaze duration within the same feature when preceded by scrambled faces. In experiment 2, a similar paradigm was used except that test faces were cued by intact faces, low-level blurred faces, or slightly scrambled faces. The results suggested that in the intact condition participants performed fewer interfeatural saccades than in low-level blurred condition and had shorter gaze duration than in slightly scrambled condition. Moreover, a few fixations in the center of the face were performed to grasp the information from the whole face. The results suggest a differentiation between featural, configural, and holistic processing strategies, which can be associated with specific patterns of eye movements. By inducing different processing strategies in experiment 1, we provided further evidence that faces can be recognized on the basis of both featural and configural information. In experiment 2 a holistic strategy characterized by the grasp of the whole face was applied, while in experiment 1 a configural strategy was adopted when the information from different locations was integrated by performing a high number of saccades between different features. In conclusion, the present study shows that three modes of face processing strategies coexist in face perception.

An MEG neuroimaging study on the developmental changes of face processing in pre-school aged children

Event Abstract Back to Event An MEG neuroimaging study on the developmental changes of face processing in pre-school aged children Wei He1*, Jon Brock1 and Blake W. Johnson1 1 Macquarie University, Department of Cognitive Science, Australia Introduction: An important research question in developmental neuroscience concerns how the underlying neural mechanisms of face perception develop in early childhood. Magnetoencephalography (MEG) holds great promise for examining this question, because it measures a well-known face sensitive brain response, termed the M170, from young children in an entirely passive manner. The M170 and its electrical equivalent N170 discriminate faces from other non-face objects based on larger amplitudes to face stimuli around 170 ms from stimulus onsets in adults (Rossion & Jacques, 2011). The current study measured the M170 from pre-schoolers using a unique child custom-sized magnetoencephalography (MEG) system (Johnson et al., 2010). Furthermore, we evaluated the effective connectivity of cortical networks underlying the M170 using dynamic causal modelling (DCM); and compared the connectivity patterns in children to those of adults. Methods: Brain responses were measured from 15 young children (aged 4.46 ± 0.93 years) and 15 adults (aged 27.6 ± 6.46 years) during flashing pictures of faces, cars, as well as their phase-scrambled counterparts (Kuefner et al, 2010). There were 64 channels in the child MEG system and 160 channels in the adult MEG system. Surface waveforms were analysed by averaging the strongest response across occipital and temporal sensors separately on each hemisphere based on the time window determined by visual checking on individual data. DCM analyses assumed that the M170 was mediated by sources in the occipital face area (OFA), fusiform face area (FFA), and superior temporal sulcus (STS). Using Bayesian model selection, we evaluated three models of the interconnections between these regions based on previous studies using DCM (Fairhall & Ishai, 2007; Chen, et al., 2009; David et al., 2006). Results: In the surface waveform analysis, the child M170 was slower than the adult M170, but it already showed an adult function pattern (i.e., faster and stronger to faces than cars). Analyses of DCM models showed that the first and simplest model with only forward intra-hemispheric connections from OFA to FFA and STS had the largest model evidence in adults, while in children, the second model with extra inter-hemispheric connections between OFA and contralateral FFA showed the largest model evidence. Conclusions: Early face sensitive brain responses indexed by the M170 are present and functioning in the adult pattern in children as young as 4 years old. However, the functional neural mechanism underlying the M170 undergoes further development and fine-tuning before it reaches adult capacities. Acknowledgements This work was supported by Australian Research Council Linkage Infrastructure Equipment and Facilities Grant LEO668421, Australian Research Council Linkage Project Grant LP0669471, and the Australian Research Council Centre of Excellence for Cognition and its Disorders (CE110001021), http://www.ccd.edu.au. The authors thank Romina Polermo and Douglas Cheyne for helpful comments during the design of the experiment and Bruno Russion for providing the picture stimuli.

Visual Gnosis and Face Perception

There are two major parallel pathways in humans: the parvocellular (P) and magnocellular (M) pathways. The former has excellent spatial resolution with color selectivity, while the latter shows excellent temporal resolution with high contrast sensitivity. Visual stimuli should be tailored to answer specific clinical and/or research questions. This chapter examines the neural mechanisms of face perception using event-related potentials (ERPs). Face stimuli of different spatial frequencies were used to investigate how low-spatial-frequency (LSF) and high-spatial-frequency (HSF) components of the face contribute to the identification and recognition of the face and facial expressions. The P100 component in the occipital area (Oz), the N170 in the posterior temporal region (T5/T6) and late components peaking at 270-390 ms (T5/T6) were analyzed. LSF enhanced P100, while N170 was augmented by HSF irrespective of facial expressions. This suggested that LSF is important for global processing of facial expressions, whereas HSF handles featural processing. There were significant amplitude differences between positive and negative LSF facial expressions in the early time windows of 270-310 ms. Subsequently, the amplitudes among negative HSF facial expressions differed significantly in the later time windows of 330–390 ms. Discrimination between positive and negative facial expressions precedes discrimination among different negative expressions in a sequential manner based on parallel visual channels. Interestingly, patients with schizophrenia showed decreased spatial frequency sensitivities for face processing. Taken together, the spatially filtered face images are useful for exploring face perception and recognition.

A steady-state visual evoked potential approach to individual face perception: Effect of inversion, contrast-reversal and temporal dynamics

Presentation of a face stimulus for several seconds at a periodic frequency rate leads to a right occipito-temporal evoked steady-state visual potential (SSVEP) confined to the stimulation frequency band. According to recent evidence (Rossion and Boremanse, 2011), this face-related SSVEP is largely reduced in amplitude when the exact same face is repeated at every stimulation cycle as compared to the presentation of different individual faces. Here this SSVEP individual face repetition effect was tested in 20 participants stimulated with faces at a 4 Hz rate for 84 s, in 4 conditions: faces upright or inverted, normal or contrast-reversed (2×2 design). To study the temporal dynamics of this effect, all stimulation sequences started with 15s of identical faces, after which, in half of the sequences, different faces were introduced. A larger response to different than identical faces at the fundamental (4 Hz) and second harmonic (8 Hz) components was observed for upright faces over the right occipito-temporal cortex. Weaker effects were found for inverted and contrast-reversed faces, two stimulus manipulations that are known to greatly affect the perception of facial identity. Addition of the two manipulations further decreased the effect. The phase of the fundamental frequency SSVEP response was delayed for inverted and contrast-reversed faces, to the same extent as the latency delay observed at the peak of the face-sensitive N170 component observed at stimulation sequence onset. Time-course analysis of the entire sequence of stimulation showed an immediate increase of 4Hz amplitude at the onset (16th second) of different face presentation, indicating a fast, large and frequency-specific release to individual face adaptation in the human brain. Altogether, these observations increase our understanding of the characteristics of the human steady-state face potential response and provide further support for the interest of this approach in the study of the neurofunctional mechanisms of face perception.

Same but different: 9-month-old infants at average and high risk for autism look at the same facial features but process them using different brain mechanisms.

The study examined whether 9-month-old infants at average vs. high risk for autism spectrum disorder (ASD) process facial features (eyes, mouth) differently and whether such differences are related to infants' social and communicative skills. Eye tracking and visual event-related potentials (ERPs) were recorded in 35 infants (20 average-risk typical infants, 15 high-risk siblings of children with ASD) while they viewed photographs of a smiling unfamiliar female face. On 30% of the trials, the eyes or the mouth of that face was replaced with corresponding features from a different female. There were no group differences in the number, duration, or distribution of fixations, and all infants looked at the eyes and mouth regions equally. However, increased attention to the mouth was associated with weaker receptive communication skills and increased attention to the eyes correlated with better interpersonal skills. ERP results revealed that all infants detected eye and mouth changes but did so using different brain mechanisms. Changes in facial features were associated with changes in activity of the face perception mechanisms (N290) for the average-risk group but not for the high-risk infants. For all infants, correlations between ERP and eye-tracking measures indicated that larger and faster ERPs to feature changes were associated with fewer fixations on the irrelevant regions of stimuli. The size and latency of the ERP responses also correlated with parental reports of receptive and expressive communication skills, suggesting that differences in brain processing of human faces are associated with individual differences in social-communicative behaviors.