Effects of repetition learning on upright, inverted and contrast-reversed face processing using ERPs

Altered face perception in amnestic mild cognitive impairment: Evidence from representational similarity analysis of event-related potential

BackgroundStructural changes in medial temporal lobes including the fusiform gyrus, a critical area in face recognition, precede the progression of amnestic mild cognitive impairment (aMCI) to Alzheimer's disease (AD). However, how the neural correlates of face processing altered in aMCI, as well as their association with cognitive impairments, remain unclear.ObjectiveUsing electroencephalogram (EEG), we explored the electrophysiological markers of face-specific visual processing alterations in aMCI and examined their relationship with cognitive deficits.MethodsWe recruited participants with aMCI (n = 32) and healthy controls (HC, n = 41) and used a passive viewing task to measure the event-related potential (ERP) in response to faces and non-face objects. To compare face processing in aMCI patients and HCs, we adopted mass univariate analysis and representational similarity analysis (RSA) to explore aMCI-related alterations in ERPs.ResultsWe found that face inversion effect (FIE) in P1 amplitudes was absent in aMCI patients. Also, compared to HCs, aMCI patients exhibited a lack of right hemisphere advantage in N170 in response to faces. Furthermore, representation similarity analysis of ERP in posterior-temporal regions revealed that aMCI patients represent face and non-face objects distinctively from HCs in the early processing stage. Additionally, the FIE in P1 amplitude positively correlated to aMCI patients' visuospatial functions.ConclusionsThese findings showed aMCI-related changes in the early perceptual processing of faces and highlights the potential of the FIE in P1 amplitude and ERP patterns over occipital-temporal regions as electrophysiological markers for aMCI and AD.

Saccade execution increases the preview effect with faces: An EEG and eye-tracking coregistration study

Under naturalistic viewing conditions, humans conduct about three to four saccadic eye movements per second. These dynamics imply that in real life, humans rarely see something completely new; there is usually a preview of the upcoming foveal input from extrafoveal regions of the visual field. In line with results from the field of reading research, we have shown with EEG and eye-tracking coregistration that an extrafoveal preview also affects postsaccadic visual object processing and facilitates discrimination. Here, we ask whether this preview effect in the fixation-locked N170, and in manual responses to the postsaccadic target face (tilt discrimination), requires saccade execution. Participants performed a gaze-contingent experiment in which extrafoveal face images could change their orientation during a saccade directed to them. In a control block, participants maintained stable gaze throughout the experiment and the extrafoveal face reappeared foveally after a simulated saccade latency. Compared with this no-saccade condition, the neural and the behavioral preview effects were much larger in the saccade condition. We also found shorter first fixation durations after an invalid preview, which is in contrast to reading studies. We interpret the increased preview effect under saccade execution as the result of the additional sensorimotor processes that come with gaze behavior compared with visual perception under stable fixation. In addition, our findings call into question whether EEG studies with fixed gaze capture key properties and dynamics of active, natural vision.

Effects of Inversion and Fixation Location on the Processing of Face and House Stimuli - A Mass Univariate Analysis

Most Event Related Potential studies investigating the time course of visual processing have focused mainly on the N170 component. Stimulus orientation affects the N170 amplitude for faces but not for objects, a finding interpreted as reflecting holistic/configural processing for faces and featural processing for objects. Furthermore, while recent studies suggest where on the face people fixate impacts the N170, fixation location effects have not been investigated in objects. A data-driven mass univariate analysis (all time points and electrodes) was used to investigate the time course of inversion and fixation location effects on the neural processing of faces and houses. Strong and widespread orientation effects were found for both faces and houses, from 100-350ms post-stimulus onset, including P1 and N170 components, and later, a finding arguing against a lack of holistic processing for houses. While no clear fixation effect was found for houses, fixation location strongly impacted face processing early, reflecting retinotopic mapping around the C2 and P1 components, and during the N170-P2 interval. Face inversion effects were also largest for nasion fixation around 120ms. The results support the view that facial feature integration (1) depends on which feature is being fixated and where the other features are situated in the visual field, (2) occurs maximally during the P1-N170 interval when fixation is on the nasion and (3) continues past 200ms, suggesting the N170 peak, where weak effects were found, might be an inflexion point between processes rather than the end of a feature integration into a whole process.

Stimulus Inversion and Emotional Expressions Independently Affect Face and Body Perception: An ERP Study

Faces and bodies provide critical cues for social interaction and communication. Their structural encoding depends on configural processing, as suggested by the detrimental effect of stimulus inversion for both faces (i.e., face inversion effect - FIE) and bodies (body inversion effect - BIE). An occipito-temporal negative event-related potential (ERP) component peaking around 170 ms after stimulus onset (N170) is consistently elicited by human faces and bodies and is affected by the inversion of these stimuli. Albeit it is known that emotional expressions can boost structural encoding (resulting in larger N170 components for emotional than for neutral faces), little is known about body emotional expressions. Thus, the current study investigated the effects of different emotional expressions on structural encoding in combination with FIE and BIE. Three ERP components (P1, N170, P2) were recorded using a 128-channel electroencephalogram (EEG) when participants were presented with (upright and inverted) faces and bodies conveying four possible emotions (happiness, sadness, anger, fear) or no emotion (neutral). Results demonstrated that inversion and emotional expressions independently affected the Accuracy and amplitude of all ERP components (P1, N170, P2). In particular, faces showed specific effects of emotional expressions during the structural encoding stage (N170), while P2 amplitude (representing top-down conceptualisation) was modified by emotional body perception. Moreover, the task performed by participants (i.e., implicit vs. explicit processing of emotional information) differently influenced Accuracy and ERP components. These results support integrated theories of visual perception, thus speaking in favour of the functional independence of the two neurocognitive pathways (one for structural encoding and one for emotional expression analysis) involved in social stimuli processing. Results are discussed highlighting the neurocognitive and computational advantages of the independence between the two pathways.

Altered dynamic network interactions in children with ASD during face recognition revealed by time-varying EEG networks

Although the electrophysiological event-related potential in face processing (e.g. N170) is widely accepted as a face-sensitivity biomarker that is deficient in children with autism spectrum disorders, the time-varying brain networks during face recognition are still awaiting further investigation. To explore the social deficits in autism spectrum disorder, especially the time-varying brain networks during face recognition, the current study analyzed the N170, cortical activity, and time-varying networks under 3 tasks (face-upright, face-inverted, and house-upright) in autism spectrum disorder and typically developing children. The results revealed a smaller N170 amplitude in autism spectrum disorder compared with typically developing, along with decreased cortical activity mainly in occipitotemporal areas. Concerning the time-varying networks, the atypically stronger information flow and brain network connections across frontal, parietal, and temporal regions in autism spectrum disorder were reported, which reveals greater effort was exerted by autism spectrum disorder to obtain comparable performance to the typically developing children, although the amplitude of N170 was still smaller than that of the typically developing children. Different brain activation states and interaction patterns of brain regions during face processing were discovered between autism spectrum disorder and typically developing. These findings shed light on the face-processing mechanisms in children with autism spectrum disorder and provide new insight for understanding the social dysfunction of autism spectrum disorder.

A randomized cross-over trial investigating the neurocognitive effects of acute exercise on face recognition in children with autism spectrum disorder

Difficulties in face recognition contribute to social-cognitive problems in autistic children. Evidence on behavioral interventions targeting this cognitive domain is limited. In non-autistic individuals, a single exercise session is known to elicit temporary benefits for several cognitive functions. Our study investigates whether acute aerobic exercise influences face recognition in autistic children. In a randomized order, 29 participants completed a 20-min moderately-intense cycling bout on an ergometer and a control condition. Before and after each condition, participants categorized Mooney faces and instruments during a computerized cognitive task. Simultaneously, the N170 component of event-related potentials and pupil size were recorded using electroencephalography and eyetracking, respectively. As indicated by a greater increase of reaction time in the exercise compared to the control condition, the results revealed impaired face recognition following aerobic exercise. This effect was accompanied by a lower decrease of the positive N170 amplitude and a trend towards a greater constriction of the pupil size in the exercise compared to the control condition. Our findings highlight the interplay of the physiological state and face recognition in autistic children. Exercise-induced impairments in this social-cognitive ability may be due to an interference with the learning effect that is typically seen for the structural encoding of faces.

Semantic satiation of emotional words impedes facial expression processing in two stages

To explore the mechanism of emotional words semantic satiation effect on facial expression processing, participants were asked to judge the facial expression (happiness or sadness) after an emotional word ((cry) or (smile)) or a neutral word ((Ah), baseline condition) was presented for 20 s. The results revealed that participants were slower in judging valence-congruent facial expressions and reported a more enlarged (Experiment 1) and prolonged (Experiment 2) N170 component than the baseline condition. No significant difference in behavior and N170 appeared between the valence-incongruent and the baseline condition. However, the amplitude of LPC (Late Positive Complex) under both valence-congruent/incongruent conditions was smaller than the baseline condition. It indicates that, in the early stage, the impeding effect of satiated emotional words is specifically constrained to facial expressions with the same emotional valence; in the late stage, such an impeding effect might spread to facial expressions with the opposite valence of the satiated emotional word.

Face recognition ability is manifest in early dynamic decoding of face-orientation selectivity-Evidence from multi-variate pattern analysis of the neural response

Although humans are considered to be face experts, there is a well-established reliable variation in the degree to which neurotypical individuals are able to learn and recognise faces. While many behavioural studies have characterised these differences, studies that seek to relate the neuronal response to standardised behavioural measures of ability remain relatively scarce, particularly so for the time-resolved approaches and the early response to face stimuli. In the present study we make use of a relatively recent methodological advance, multi-variate pattern analysis (MVPA), to decode the time course of the neural response to faces compared to other object categories (inverted faces, objects). Importantly, for the first time, we directly relate metrics of this decoding assessed at the individual level to gold-standard measures of behavioural face processing ability assessed in an independent task. Thirty-nine participants completed the behavioural Cambridge Face Memory Test (CFMT), then viewed images of faces and houses (presented upright and inverted) while their neural activity was measured via electroencephalography. Significant decoding of both face orientation and face category were observed in all individual participants. Decoding of face orientation, a marker of more advanced face processing, was earlier and stronger in participants with higher levels of face expertise, while decoding of face category information was earlier but not stronger for individuals with greater face expertise. Taken together these results provide a marker of significant differences in the early neuronal response to faces from around 100 ms post stimulus as a function of behavioural expertise with faces.

Electrophysiological Studies of Reception of Facial Communication in Autism Spectrum Disorder and Schizophrenia

Autism spectrum disorder (ASD) and schizophrenia spectrum disorders (SZ) are characterized by difficulty with social cognition and atypical reception of facial communication - a key area in the Research Domain Criteria framework. To identify areas of overlap and dissociation between ASD and SZ, we review studies of event-related potentials (ERP) to faces across ASD and SZ populations, focusing on ERPs implicated in social perception: P100, N170, N250, and P300. There were many inconsistent findings across studies; however, replication was strongest for delayed N170 latency in ASD and attenuated N170 amplitude in SZ. These results highlight the challenges of replicating research findings in heterogeneous clinical populations and the need for transdiagnostic research that continuously quantifies behavior and neural activity across neurodevelopmental disorders.

Contrast reversal of the iris and sclera increases the face sensitive N170

Previous research has demonstrated that reversing the contrast of the eye region, which includes the eyebrows, affects the N170 ERP. To selectively assess the impact of just the eyes, the present study evaluated the N170 in response to reversing contrast polarity of just the iris and sclera in upright and inverted face stimuli. Contrast reversal of the eyes increased the amplitude of the N170 for upright faces, but not for inverted faces, suggesting that the contrast of eyes is an important contributor to the N170 ERP.

Neural sensitivity to faces is increased by immersion into a novel ethnic environment: Evidence from ERPs

Previous reports suggest that East-Asians may show larger face-elicited N170 components in the ERP as compared to Caucasian participants. Since the N170 can be modulated by perceptual expertise, such group differences may be accounted for by differential experience, for example, with logographic versus alphabetic scripts (script system hypothesis) or by exposure to abundant novel faces during the immersion into a new social and/or ethnic environment (social immersion hypothesis). We conducted experiments in Hong Kong and Berlin, recording ERPs in a series of one-back tasks, using same- and other-ethnicity face stimuli in upright and inverted orientation and doodle stimuli. In Hong Kong we tested local Chinese residents and foreign guest students who could not read the logographic script; in Berlin we tested German residents who could not read the logographic script and foreign Chinese visitors. In both experiments, we found significantly larger N170 amplitudes to faces, regardless of ethnicity, in the foreign than in the local groups. Moreover, this effect did not depend on stimulus orientation, suggesting that the N170 group differences do not reflect differences in configural visual processing. A group of short-term German residents in Berlin did not differ in N170 amplitude from long-term residents. Together, these findings indicate that the extensive confrontation with novel other-ethnicity faces during immersion in a foreign culture may enhance the neural response to faces, reflecting the short-term plasticity of the underlying neural system.

Event-Related Potential Assessment of Visual Perception Abnormality in Patients With Obstructive Sleep Apnea: A Preliminary Study

This study investigated the effect of obstructive sleep apnea (OSA) on the neural mechanism of visual perception. A preliminary case-control study was conducted. Seventeen patients with moderate to severe OSA in the sleep center of Civil Aviation General Hospital and 20 healthy controls matched for age, sex, and education were recruited. The participants accepted the perceptual contour integration task, compared the differences in behavioral indicators between the two groups, and compared the differences in electroencephalography (EEG) data between the two groups through event-related potential (ERP) technology. The groups did not differ significantly in age and gender, but they differed significantly in body mass index (BMI) (OSA higher than healthy controls, p < 0.05). The groups were not statistically different in terms of sleep structure and total sleep time. AHI, sleep efficiency, and minimal SaO2 value in the OSA group were significantly different from those of the control group. The results showed that the average reaction time of the OSA group was significantly longer than that of the healthy control group in the contour integration task. There was no significant difference in the accuracy rate. The results of EEG showed that the amplitudes of N100 of the OSA group were significantly higher than those of the control group at O1, Oz, and O2 electrodes. There was no significant difference in latency between the two groups. At the FCz electrode, the amplitudes of N200 of the OSA group were significantly higher than those of the control group. Therefore, we concluded that in the early stage of the perceptual integration task, although the neural response activity of patients with moderate and severe OSA was not accelerated, they need to call on more psychological resources, activate more neurons in the contour global recognition processing stage, and the compensatory effect of frontal lobe appeared in the stage of visual perception.

Twenty years of investigation with the case of prosopagnosia PS to understand human face identity recognition. Part II: Neural basis

Patient PS sustained her dramatic brain injury in 1992, the same year as the first report of a neuroimaging study of human face recognition. The present paper complements the review on the functional nature of PS's prosopagnosia (part I), illustrating how her case study directly, i.e., through neuroimaging investigations of her brain structure and activity, but also indirectly, through neural studies performed on other clinical cases and neurotypical individuals, inspired and constrained neural models of human face recognition. In the dominant right hemisphere for face recognition in humans, PS's main lesion concerns (inputs to) the inferior occipital gyrus (IOG), in a region where face-selective activity is typically found in normal individuals ('Occipital Face Area', OFA). Her case study initially supported the criticality of this region for face identity recognition (FIR) and provided the impetus for transcranial magnetic stimulation (TMS), intracerebral electrical stimulation, and cortical surgery studies that have generally supported this view. Despite PS's right IOG lesion, typical face-selectivity is found anteriorly in the middle portion of the fusiform gyrus, a hominoid structure (termed the right 'Fusiform Face Area', FFA) that is widely considered to be the most important region for human face recognition. This finding led to the original proposal of direct anatomico-functional connections from early visual cortices to the FFA, bypassing the IOG/OFA (lulu), a hypothesis supported by further neuroimaging studies of PS, other neurological cases and neuro-typical individuals with original visual stimulation paradigms, data recordings and analyses. The proposal of a lack of sensitivity to face identity in PS's right FFA due to defective reentrant inputs from the IOG/FFA has also been supported by other cases, functional connectivity and cortical surgery studies. Overall, neural studies of, and based on, the case of prosopagnosia PS strongly question the hierarchical organization of the human neural face recognition system, supporting a more flexible and dynamic view of this key social brain function.

The spatiotemporal characteristics of N170s for faces and words: A meta-analysis study

N170 is a negative event-related potential (ERP) component in response to visual stimuli, such as faces. It remains controversial whether N170 reflects the specific processing of faces or can also be elicited by objects of expertise (e.g., words). In this research, we conducted a meta-analysis for the spatiotemporal characteristics of N170 of face and word stimuli from 24 studies in which both stimuli were presented for each subject. We observed that (1) both face and word stimuli can elicit conspicuous N170s and that there was no difference between the amplitude of face-N170 and word-N170; (2) there is no difference in the latencies between the two N170s; and (3) both N170s are distributed in the occipitotemporal regions but with a reversed hemispheric distribution pattern-face-N170 is more negative in the right than left occipitotemporal regions, while word-N170 is the opposite. These results showed that the face- and word-N170s are qualitatively the same but have different hemispheric lateralization advantages-N170 might be a general neural index of the expertise-dependent object-recognition process in occipitotemporal regions.

Contrast Adaptation in Face Perception Revealed Through EEG and Behavior

Exposure to a face can produce biases in the perception of subsequent faces. Typically, these face aftereffects are studied by adapting to an individual face or category (e.g., faces of a given gender) and can result in renormalization of perceptions such that the adapting face appears more neutral. These shifts are analogous to chromatic adaptation, where a renormalization for the average adapting color occurs. However, in color vision, adaptation can also adjust to the variance or range of colors in the distribution. We examined whether this variance or contrast adaptation also occurs for faces, using an objective EEG measure to assess response changes following adaptation. An average female face was contracted or expanded along the horizontal or vertical axis to form four images. Observers viewed a 20 s sequence of the four images presented in a fixed order at a rate of 6 Hz, while responses to the faces were recorded with EEG. A 6 Hz signal was observed over right occipito-temporal channels, indicating symmetric responses to the four images. This test sequence was repeated after 20 s adaptation to alternations between two of the faces (e.g., horizontal contracted and expanded). This adaptation resulted in an additional signal at 3 Hz, consistent with asymmetric responses to adapted and non-adapted test faces. Adapting pairs have the same mean (undistorted) as the test sequence and thus should not bias responses driven only by the mean. Instead, the results are consistent with selective adaptation to the distortion axis. A 3 Hz signal was also observed after adapting to face pairs selected to induce a mean bias (e.g., expanded vertical and expanded horizontal), and this signal was not significantly different from that observed following adaption to a single image that did not form part of the test sequence (e.g., a single image expanded both vertically and horizontally). In a further experiment, we found that this variance adaptation can also be observed behaviorally. Our results suggest that adaptation calibrates face perception not only for the average characteristics of the faces we experience but also for the gamut of faces to which we are exposed.

Altering sensorimotor simulation impacts early stages of facial expression processing depending on individual differences in alexithymic traits

Simulation models of facial expressions suggest that posterior visual areas and brain areas underpinning sensorimotor simulations might interact to improve facial expression processing. According to these models, facial mimicry, a manifestation of sensorimotor simulation, may contribute to the visual processing of facial expressions by influencing early stages. The aim of this study was to assess whether and how sensorimotor simulation influences early stages of face processing, also investigating its relationship with alexithymic traits given that previous studies have suggested that individuals with high levels of alexithymic traits (vs. individuals with low levels of alexithymic traits) tend to use sensorimotor simulation to a lesser extent. We monitored P1 and N170 ERP components of the event-related potentials (ERP) in participants performing a fine discrimination task of facial expressions and animals, as a control condition. In half of the experiment, participants could freely use their facial mimicry whereas in the other half they had their facial mimicry blocked by a gel. Our results revealed that only individuals with lower compared to high alexithymic traits showed a larger modulation of the P1 amplitude as a function of the mimicry manipulation selectively for facial expressions (but not for animals), while we did not observe any modulation of the N170. Given the null results at the behavioural level, we interpreted the P1 modulation as compensative visual processing in individuals with low levels of alexithymia under conditions of interference on the sensorimotor processing, providing a preliminary evidence in favor of sensorimotor simulation models.

Do perceptual expertise and implicit racial bias predict early face-sensitive ERP responses?

Studies examining the visual perception of face race have revealed mixed findings regarding the presence or direction of effects on early face-sensitive event-related potential (ERP) components. Few studies have examined how early ERP components are influenced by individual differences in bottom-up and top-down processes involved in face perception, and how such factors might interact to influence early face-sensitive ERP components has yet to be investigated. Thus, the current study examined whether P100, N170, and P200 responses can be predicted by individual differences in own- and other-race face recognition, implicit racial bias, and their interaction. Race effects were observed in the P100, N170, and P200 responses. Other-race face recognition, implicit racial biases, and their interaction explained a significant amount of unique variability in N170 responses when viewing other-race faces. Responses to own-race faces were minimally influenced with only implicit racial bias predicting a significant amount of unique variability in N170 latency when viewing own-race faces. Face recognition, implicit racial bias, or their interaction did not predict P100 responses. The current findings suggest that face recognition abilities and its interaction with implicit racial bias modulate the early stages of other-race face processing.

Configural processing of emotional bodies and faces in patients with attention deficit hyperactivity disorder

Introduction: Attention Deficit Disorder (ADHD) is associated with interpersonal problems and difficulties in inferring other peoples' emotions. Previous research has focused on face processing, mostly in children. Our study investigated configural processing of emotional bodies and faces in adults with ADHD in comparison with healthy controls, analyzing P100, N170 and P250 event-related potentials (ERPs) and relating them to (socio)cognitive functioning. Method: Nineteen patients with ADHD and 25 healthy controls were presented upright and inverted bodies and faces which had to be categorized as neutral, happy or angry while ERPs were recorded. Additionally, sociocognitive and executive functioning was assessed. Results: In ADHD patients relative to controls, recognition of emotions depicted by bodies but not by faces was impaired and P100 amplitudes were enhanced for angry bodies. Furthermore, patients showed enhanced P250 amplitudes in response to both bodies and faces, specifically for happy and neutral emotions. Larger N170 amplitudes to bodies and faces correlated with lower alexithymia scores only in controls, while enhanced P250 amplitudes to both categories were associated with poorer inhibition only in patients. Conclusion: Adults with ADHD show potentially compensatory enhanced semantic processing of emotional bodies and faces, as reflected by increased P250 amplitudes, associated with poorer executive functioning and subtle alterations of emotional and configural processing, as reflected by ERPs.

Attentional and emotional brain response to message framing in context of green marketing

Background

Message framing plays an important role in advertising strategies and has been studied from various perspectives in different behavioral studies.

New method

This study employs the event-related potential technique to examine attentional and emotional brain processing as influenced by message framing in the context of green marketing.

Results

The behavioral results demonstrated that purchase preference was higher under positive framing compared to negative and neutral framing.

As per the event-related potential results, negative framing elicited a larger P1 component, which reveals that in the first stage of processing information, threatening information attracted more attention. In the second and third stage, N170 and P3, respectively, were higher for positive framing, demonstrating that there was more attention toward the processing of non-threatening emotional information.

Comparison with existing method: Message Framing has been previously examined with behavioral methods. We for the first time examined it with a neuroscientific method like Event Related Brain Potential technique in a green marketing context.

Conclusion

Our results compared to behavioral studies provide stronger evidence from underlying neural perspective for how message framing can be affected by attentional and emotional brain responses in the context of green marketing.

Low Spatial Frequency Sensitivity and Emotional Face Processing in Adolescents: An Event-related Potential Study

Slow maturation of visual pathways transmitting low spatial frequency (LSF) information may contribute to inaccurate facial emotion recognition in adolescence. We recorded ERPs from adolescents and adults to upright and inverted happy faces, fearful faces, and chairs, which were unfiltered, contained only LSFs, or only high spatial frequencies. P100s and N170s were larger for adolescents than adults, with the greatest effect size for LSF stimuli. For LSFs only, adolescents showed a larger N170 inversion effect for happy than for fearful faces, but adults showed the opposite response. Thus, immaturities in LSF pathways appear to impact facial expression processing in adolescents.

The peripheral preview effect with faces: Combined EEG and eye-tracking suggests multiple stages of trans-saccadic predictive and non-predictive processing

The world appears stable despite saccadic eye-movements. One possible explanation for this phenomenon is that the visual system predicts upcoming input across saccadic eye-movements based on peripheral preview of the saccadic target. We tested this idea using concurrent electroencephalography (EEG) and eye-tracking. Participants made cued saccades to peripheral upright or inverted face stimuli that changed orientation (invalid preview) or maintained orientation (valid preview) while the saccade was completed. Experiment 1 demonstrated better discrimination performance and a reduced fixation-locked N170 component (fN170) with valid than with invalid preview, demonstrating integration of pre- and post-saccadic information. Moreover, the early fixation-related potentials (FRP) showed a preview face inversion effect suggesting that some pre-saccadic input was represented in the brain until around 170 ms post fixation-onset. Experiment 2 replicated Experiment 1 and manipulated the proportion of valid and invalid trials to test whether the preview effect reflects context-based prediction across trials. A whole-scalp Bayes factor analysis showed that this manipulation did not alter the fN170 preview effect but did influence the face inversion effect before the saccade. The pre-saccadic inversion effect declined earlier in the mostly invalid block than in the mostly valid block, which is consistent with the notion of pre-saccadic expectations. In addition, in both studies, we found strong evidence for an interaction between the pre-saccadic preview stimulus and the post-saccadic target as early as 50 ms (Experiment 2) or 90 ms (Experiment 1) into the new fixation. These findings suggest that visual stability may involve three temporal stages: prediction about the saccadic target, integration of pre-saccadic and post-saccadic information at around 50-90 ms post fixation onset, and post-saccadic facilitation of rapid categorization.

The neural sources of N170: Understanding timing of activation in face-selective areas

The N170 ERP component has been widely identified as a face-sensitive neural marker. Despite extensive investigations conducted to examine the neural sources of N170, there are two issues in prior literature: (a) few studies used individualized anatomy as head model for the cortical source analysis of the N170, and (b) the relationship between the N170 and face-selective regions from fMRI studies is unclear. Here, we addressed these questions by presenting pictures of faces and houses to the same group of healthy adults and recording structural MRI, fMRI, and high-density ERPs in separate sessions. Source analysis based on the participant's anatomy showed that the middle and posterior fusiform gyri were the primary neural sources for the face-sensitive aspects of the N170. Source analysis based on regions of interest from the fMRI revealed that the fMRI-defined fusiform face area was the major contributor to the N170. The current study suggests that the fusiform gyrus is a major neural contributor to the N170 ERP component and provides further insights about the spatiotemporal characteristics of face processing.

The Relationship Between Social Power and Sexual Objectification: Behavioral and ERP Data

Sexual objectification is very common in modern Western societies, especially toward women. Previous research has suggested that in Western cultures, social power could lead to objectification. Specifically, power activates an approaching tendency toward useful targets, in turn leading to instrumental objectification and sexual objectification of targets. However, previous research has mostly focused on Western cultures, and the neural correlates underlying this phenomenon remain unclear. To examine whether the effects of power can be generalized to Chinese cultural contexts and how power promotes the objectification of sexualized bodies, we conducted two studies using Chinese samples. In Study 1, we replicated the behavioral effects of social power on sexual objectification. Specifically, we found that power increased sexual objectification toward sexualized female rather than male bodies. In Study 2, we examined the absence of an N170 amplitude inversion effect as a possible neural correlate of sexual objectification and replicated the effects of power on sexual objectification through event-related potentials (ERPs). For participants in a high-power group, the N170 amplitude inversion effect emerged when processing sexualized male bodies (less sexual objectification) but not female bodies (more sexual objectification); this effect was not seen for those participants in a low-power group. Our findings provide behavioral and neural data that power leads to increased sexual objectification toward sexualized women in Chinese participants.

Early identity recognition of familiar faces is not dependent on holistic processing

It is widely accepted that holistic processing is critical for early face recognition, but recent work has suggested a larger role for feature-based processing. The earliest step in familiar face recognition is thought to be matching a perceptual representation of a familiar face to a stored representation of that face, which is thought to be indexed by the N250r event-related potential (ERP). In the current face-priming studies, we investigated whether this perceptual representation can be effectively activated by feature-based processing. In the first experiment, prime images were familiar whole faces, isolated eyes or isolated mouths. Whole faces and isolated eyes, but not isolated mouths, effectively modulated the N250r. In the second experiment, prime images were familiar whole faces presented either upright or inverted. Inverted face primes were no less effective than upright face primes in modulating the N250r. Together, the results of these studies indicate that activation of the earliest face recognition processes is not dependent on holistic processing of a typically configured face. Rather, feature-based processing can effectively activate the perceptual memory of a familiar face. However, not all features are effective primes as we found eyes, but not mouths, were effective in activating early face recognition.

Effects of Repeated Concussions and Sex on Early Processing of Emotional Facial Expressions as Revealed by Electrophysiology

OBJECTIVES

Concussions affect the processing of emotional stimuli. This study aimed to investigate how sex interacts with concussion effects on early event-related brain potentials (ERP) measures (P1, N1) of emotional facial expressions (EFE) processing in asymptomatic, multi-concussion athletes during an EFE identification task.

METHODS

Forty control athletes (20 females and 20 males) and 43 multi-concussed athletes (22 females and 21 males), recruited more than 3 months after their last concussion, were tested. Participants completed the Beck Depression Inventory II, the Beck Anxiety Inventory, the Post-Concussion Symptom Scale, and an Emotional Facial Expression Identification Task. Pictures of male and female faces expressing neutral, angry, and happy emotions were randomly presented and the emotion depicted had to be identified as fast as possible during EEG acquisition.

RESULTS

Relative to controls, concussed athletes of both sex exhibited a significant suppression of P1 amplitude recorded from the dominant right hemisphere while performing the emotional face expression identification task. The present study also highlighted a sex-specific suppression of the N1 component amplitude after concussion which affected male athletes.

CONCLUSIONS

These findings suggest that repeated concussions alter the typical pattern of right-hemisphere response dominance to EFE in early stages of EFE processing and that the neurophysiological mechanisms underlying the processing of emotional stimuli are distinctively affected across sex. (JINS, 2018, 24, 673-683).

From coarse to fine: Interactive feature processing precedes local feature analysis in human face perception

Face perception depends on a dynamic interplay of a "holistic" Interactive Feature Processing (IFP) and a Local Feature Processing (LFP) style. However, it is unclear whether features are processed locally before they are integrated into a holistic percept (Fine-to-Coarse strategy), or whether local feature processing occurs only after a holistic percept is established (Coarse-to-Fine strategy). The present Event-Related Potentials study investigates whether IFP precedes LFP (Coarse-to-Fine) or vice versa (Fine-to-Coarse). Participants matched target features within face pairs (here the eye region), in which distracter features (nose and mouth) called for the same or a different response (congruent and incongruent, respectively). Psychophysical results replicated previous findings. That is, dissimilar target features are locally processed (LFP), which minimizes interference from surrounding incongruent distracters. Conversely, an IFP mode is elicited when similar target features are embedded in dissimilar contexts. In IFP mode, incongruent distracters do interfere with the processing of similar target features, thereby deteriorating task performance. Face inversion, which preserves input properties but disrupts high-level face perception, annihilated these incongruency effects. Psychophysical observations were reflected at the neural level. The IFP and LFP modes of face perception elicited distinct time-courses in occipito-temporal cortex. IFP was affected by inversion as soon as 176 ms post-stimulus onset (coinciding with the N170 peak). In contrast, the first robust indications of LFP occurred 120 ms later, at 296 ms. Thus, the contribution of IFP to high-level face perception appears to temporally precede LFP. Moreover, results showed that the IFP and LFP modes did not only operate in distinct time intervals, but also in different brain areas: activity associated with the IFP mode was right-lateralized, whereas the LPF mode engaged the left hemisphere. In sum, interactive "holistic" encoding of facial features temporally precedes their local analysis. This agrees with models suggesting a Coarse-to-Fine strategy for face perception, in line with generic descriptions of visual perception in which global scene analysis precedes the examination of local details.

Event-related potentials modulated by the perception of sexual dimorphism: The influence of attractiveness and sex of faces

Sexual dimorphism has been proposed as one of the facial traits to have evolved through sexual selection and to affect attractiveness perception. Even with numerous studies documenting its effect on attractiveness and mate choice, the neurophysiological correlates of the perception of sexual dimorphism are not yet fully understood. In the present study, event-related potentials (ERPs) were recorded during visualisation of faces that had been previously transformed in shape to appear more masculine or more feminine. The participants' task consisted of judging the attractiveness of half of the total number of faces, and performing a sex discrimination task on the other half. Both early and late potentials were modulated by the sex of faces, whereas the effect of the sexually dimorphic transform was mainly visible in the P2 (positive deflection around 200 ms after stimulus onset), EPN (early posterior negativity) and LPP (late positive potential) components. There was an effect of sexual dimorphism on P2 and EPN amplitudes when female participants visualised male faces, which may indicate that masculinity is particularly attended to when viewing opposite sex members. Also, ERP results seem to support the idea of sex differences in social categorisation decisions regarding faces, although differences were not evident on behavioural results. In general, these findings contribute to a better understanding of how humans perceive sexually dimorphic characteristics in other individuals' faces and how they affect attractiveness judgements.

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.

Visual cortical activity before and after cochlear implantation: A follow up ERP prospective study in deaf children

ERPs were recorded in response to presentation of static colored patterned stimuli in 25 children (19 to 80months of age at cochlear implantation, CI) with very early prelingual profound deafness (PreLD), 21 postlingual profoundly deaf children (PostLD) (34 to 180months of age at CI) and gender- and age-matched control hearing children. Recording sessions were performed before CI, then 6 and 24months after CI. Results showed that prelingual and, at a lesser degree, postlingual auditory deprivation altered cortical visual neural activity associated to colored shapes from both P1 and N1 cortical processing stages. The P1 and N1 amplitude modifications vanished about 24months after CI in both PreLD and PostLD deaf children. In PreLD the visual processing pattern becomes similar to the typical one essentially by an amplitude decrease of P1 on the left hemisphere together with an amplitude increase of the N1 on the right hemisphere. Finally, in PreLD, increased LH advantage over the RH in N1 amplitude on the cerebellar-occipito-parietal region before CI showed a significant inverse relationship with speech perception outcomes 3years after CI. Investigating early visual processing development and its neural substrates in deaf children would help to understand the variability of CI outcome, because their cortical visual organization diverged from the one of typically developing hearing children, and cannot be predicted from what is observed in deaf adults.

Event-related potentials reveal the development of stable face representations from natural variability

Natural variability between instances of unfamiliar faces can make it difficult to reconcile two images as the same person. Yet for familiar faces, effortless recognition occurs even with considerable variability between images. To explore how stable face representations develop, we employed incidental learning in the form of a face sorting task. In each trial, multiple images of two facial identities were sorted into two corresponding piles. Following the sort, participants showed evidence of having learnt the faces performing more accurately on a matching task with seen than with unseen identities. Furthermore, ventral temporal event-related potentials were more negative in the N250 time range for previously seen than for previously unseen identities. These effects appear to demonstrate some degree of abstraction, rather than simple picture learning, as the neurophysiological and behavioural effects were observed with novel images of the previously seen identities. The results provide evidence of the development of facial representations, allowing a window onto natural mechanisms of face learning.

Relative expertise affects N170 during selective attention to superimposed face-character images

It remains unclear whether the N170 of ERPs reflects domain-specific or domain-general visual object processing. In this study, we used superimposed images of a face and a Chinese character such that participants' relative expertise for the two object types was either similar (Experiment 1 and 2) or different (Experiment 3). Experiment 1 showed that N170 amplitude was larger when participants attended to the character instead of the face of a face-character combination. This result was unchanged in Experiment 2, in which task difficulty was selectively increased for the face component of the combined stimuli. Experiment 3 showed that, although this N170 enhancement for attending to characters relative to faces persisted for false characters with recognizable parts, it disappeared for unrecognizable characters. Therefore, N170 amplitude was significantly greater for Chinese characters than for faces presented within a combined image, independent of the relative task difficulty. This result strongly calls N170 face selectivity into question, demonstrating that, contrary to the expectations established by a domain-specific account, N170 is modulated by expertise.

The Effects of Face Inversion and Face Race on the P100 ERP

Research about the neural basis of face recognition has investigated the timing and anatomical substrates of different stages of face processing. Scalp-recorded ERP studies of face processing have focused on the N170, an ERP with a peak latency of ∼170 msec that has long been associated with the initial structural encoding of faces. However, several studies have reported earlier ERP differences related to faces, suggesting that face-specific processes might occur before N170. Here, we examined the influence of face inversion and face race on the timing of face-sensitive scalp-recorded ERPs by examining neural responses to upright and inverted line-drawn and luminance-matched white and black faces in a sample of white participants. We found that the P100 ERP evoked by inverted faces was significantly larger than that evoked by upright faces. Although this inversion effect was statistically significant at 100 msec, the inverted-upright ERP difference peaked at 138 msec, suggesting that it might represent an activity in neural sources that overlap with P100. Inverse modeling of the inversion effect difference waveform suggested possible neural sources in pericalcarine extrastriate visual cortex and lateral occipito-temporal cortex. We also found that the inversion effect difference wave was larger for white faces. These results are consistent with behavioral evidence that individuals process the faces of their own races more configurally than faces of other races. Taken together, the inversion and race effects observed in the current study suggest that configuration influences face processing by at least 100 msec.

Face identity is encoded in the duration of N170 adaptation

Previous studies assessing the involvement of the face-sensitive N170 component of the event-related potential (ERP) in the processing of face identity have shown controversial results when assessing N170 amplitude in repetition suppression (RS) designs. On the other hand, N170 adaptation is robustly associated with the inter-stimulus interval (ISI) between immediate face repetitions. Interestingly, interactions of face identity and ISI could provide valuable information on early encoding of face identity, but have not been investigated so far. We employed a repetition suppression paradigm using identical and non-identical repetitions as well as parametrically varied ISIs between 500 msec and 2,000 msec in 27 healthy subjects to investigate N170 adaptation effects. Both face identity and varying ISIs significantly influenced N170 adaptation effects, albeit with small effects sizes. Most importantly, however, face identity and ISIs strongly interacted with rapid N170 amplitude recovery in non-identical trials, but sustained N170 adaptation in identical trials. We excluded low-level sensory contributions to the N170 adaptation effect by analyzing the P1 component and by running an additional experiment employing different stimulus sizes. This specific result strongly argues in favor of neuronal sensitivity to face identity, which is primarily mirrored in the N170 temporal decay function that essentially differentiates identical and non-identical face trials. In general, taking advantage of the temporal dimension of adaptation processes, i.e., their decay over time, provides additional dissections of neuronal function into feature-specific selectivity versus non-selectivity.

Event-Related Potential Effects of Object Repetition Depend on Attention and Part-Whole Configuration

The effects of spatial attention and part-whole configuration on recognition of repeated objects were investigated with behavioral and event-related potential (ERP) measures. Short-term repetition effects were measured for probe objects as a function of whether a preceding prime object was shown as an intact image or coarsely scrambled (split into two halves) and whether or not it had been attended during the prime display. In line with previous behavioral experiments, priming effects were observed from both intact and split primes for attended objects, but only from intact (repeated same-view) objects when they were unattended. These behavioral results were reflected in ERP waveforms at occipital–temporal locations as more negative-going deflections for repeated items in the time window between 220 and 300 ms after probe onset (N250r). Attended intact images showed generally more enhanced repetition effects than split ones. Unattended images showed repetition effects only when presented in an intact configuration, and this finding was limited to the right-hemisphere electrodes. Repetition effects in earlier (before 200 ms) time windows were limited to attended conditions at occipito-temporal sites during the N1, a component linked to the encoding of object structure, while repetition effects at central locations during the same time window (P150) were found for attended and unattended probes but only when repeated in the same intact configuration. The data indicate that view-generalization is mediated by a combination of analytic (part-based) representations and automatic view-dependent representations.

Lag-length effect on repetition priming of famous and unfamiliar faces: evidence from N250r and N400

Previous event-related potentials research has reliably identified two repetition priming components in faces, the N250r and the N400, which are believed to reflect, respectively, the accessing to the stored structural representations and the semantic retrieval. However, the effect of lags longer than immediate repetition and shorter than 3 min on the two components has not been described as yet, and the interaction between lag length and familiarity is unclear. The current experiment aims to address these issues. In this experiment, famous and unfamiliar faces were represented after short, medium, or long lags, and participants were required to decide whether each face was known or not. The data showed that the frontal N250r, rather than the temporal counterpart, persisted to the medium lag case for famous faces; for unfamiliar faces, no N250r was observed. The frontal N400 was more regulated by lag length than the centroparietal counterpart. These results suggest that the frontal N250r and the frontal N400 are affected by the lag length; moreover, the former is more sensitive to the pre-experimental familiarity of faces.

Double dissociation of configural and featural face processing on P1 and P2 components as a function of spatial attention

Face recognition relies on both configural and featural processing. Previous research has shown that P1 is sensitive to configural face processing, but it is unclear whether any component is sensitive to featural face processing; moreover, if there is such a component, its temporal sequence relative to P1 is unknown. Thus, to avoid confounding physical stimuli differences between configural and featural face processing on ERP components, a spatial attention paradigm was employed by instructing participants to attend an image stream (faces and houses) or an alphanumeric character stream. The interaction between attention and face processing type on P1 and P2 components indicates different mechanisms of configural and featural face processing as a function of spatial attention. The steady-state visual evoked potential (SSVEP) results clearly demonstrated that participants could selectively attend to different streams of information. Importantly, configural face processing elicited a larger posterior P1 (approximately 128 ms) than featural face processing, whereas P2 (approximately 248 ms) was greater for featural than for configural face processing under attended condition. The interaction between attention and face processing type (configural vs. featural) on P1 and P2 components indicates that there are different mechanisms of configural and featural face processing operating as functions of spatial attention. While the P1 result confirms previous findings separating configural and featural face processing, the newly observed P2 finding in the present study extends this separation to a double dissociation. Therefore, configural and featural face processing are modulated differently by spatial attention, and configural face processing precedes featural face processing.