Is the face-sensitive N170 the only ERP not affected by selective attention?

Same but different: The latency of a shared expectation signal interacts with stimulus attributes

Predictive coding theories assert that perceptual inference is a hierarchical process of belief updating, wherein the onset of unexpected sensory data causes so-called prediction error responses that calibrate erroneous inferences. Given the functionally specialised organisation of visual cortex, it is assumed that prediction error propagation interacts with the specific visual attribute violating an expectation. We sought to test this within the temporal domain by applying time-resolved decoding methods to electroencephalography (EEG) data evoked by contextual trajectory violations of either brightness, size, or orientation within a bound stimulus. We found that following ∼170 ms post stimulus onset, responses to both size violations and orientation violations were decodable from physically identical control trials in which no attributes were violated. These two violation types were then directly compared, with attribute-specific signalling being decoded from 265 ms. Temporal generalisation suggested that this dissociation was driven by latency shifts in shared expectation signalling between the two conditions. Using a novel temporal bias method, we then found that this shared signalling occurred earlier for size violations than orientation violations. To our knowledge, we are among the first to decode expectation violations in humans using EEG and have demonstrated a temporal dissociation in attribute-specific expectancy violations.

Potentiated early neural responses to fearful faces are not driven by specific face parts

Prioritized processing of fearful compared to neutral faces is reflected in increased amplitudes of components of the event-related potential (ERP). It is unknown whether specific face parts drive these modulations. Here, we investigated the contributions of face parts on ERPs to task-irrelevant fearful and neutral faces using an ERP-dependent facial decoding technique and a large sample of participants (N = 83). Classical ERP analyses showed typical and robust increases of N170 and EPN amplitudes by fearful relative to neutral faces. Facial decoding further showed that the absolute amplitude of these components, as well as the P1, was driven by the low-frequency contrast of specific face parts. However, the difference between fearful and neutral faces was not driven by any specific face part, as supported by Bayesian statistics. Furthermore, there were no correlations between trait anxiety and main effects or interactions. These results suggest that increased N170 and EPN amplitudes to task-irrelevant fearful compared to neutral faces are not driven by specific facial regions but represent a holistic face processing effect.

Emotional Attention: From Eye Tracking to Computational Modeling

Attending selectively to emotion-eliciting stimuli is intrinsic to human vision. In this research, we investigate how emotion-elicitation features of images relate to human selective attention. We create the EMOtional attention dataset (EMOd). It is a set of diverse emotion-eliciting images, each with (1) eye-tracking data from 16 subjects, (2) image context labels at both object- and scene-level. Based on analyses of human perceptions of EMOd, we report an emotion prioritization effect: emotion-eliciting content draws stronger and earlier human attention than neutral content, but this advantage diminishes dramatically after initial fixation. We find that human attention is more focused on awe eliciting and aesthetic vehicle and animal scenes in EMOd. Aiming to model the above human attention behavior computationally, we design a deep neural network (CASNet II), which includes a channel weighting subnetwork that prioritizes emotion-eliciting objects, and an Atrous Spatial Pyramid Pooling (ASPP) structure that learns the relative importance of image regions at multiple scales. Visualizations and quantitative analyses demonstrate the model's ability to simulate human attention behavior, especially on emotion-eliciting content.

Shared Attention Amplifies the Neural Processing of Emotional Faces

Sharing an experience, without communicating, affects people's subjective perception of the experience, often by intensifying it. We investigated the neural mechanisms underlying shared attention by implementing an EEG study where participants attended to and rated the intensity of emotional faces, simultaneously or independently. Participants performed the task in three experimental conditions: (a) alone; (b) simultaneously next to each other in pairs, without receiving feedback of the other's responses (shared without feedback); and (c) simultaneously while receiving the feedback (shared with feedback). We focused on two face-sensitive ERP components: The amplitude of the N170 was greater in the "shared with feedback" condition compared to the alone condition, reflecting a top-down effect of shared attention on the structural encoding of faces, whereas the EPN was greater in both shared context conditions compared to the alone condition, reflecting an enhanced attention allocation in the processing of emotional content of faces, modulated by the social context. Taken together, these results suggest that shared attention amplifies the neural processing of faces, regardless of the valence of facial expressions.

Tracking cortical representations of facial attractiveness using time-resolved representational similarity analysis

When we see a face, we rapidly form an impression of its attractiveness. Here, we investigated how rapidly representations of facial attractiveness emerge in the human brain. In an EEG experiment, participants viewed 100 face photographs and rated them for their attractiveness. Using time-resolved representational similarity analysis on the EEG data, we reveal representations of facial attractiveness after 150-200 ms of cortical processing. Interestingly, we show that these representations are related to individual participants' personal attractiveness judgments, suggesting that already early perceptual representations of facial attractiveness convey idiosyncratic attractiveness preferences. Further, we show that these early representations are genuinely related to attractiveness, as they are neither explained by other high-level face attributes, such as face sex or age, nor by features extracted by an artificial deep neural network model of face processing. Together, our results demonstrate early, individually specific, and genuine representations of facial attractiveness, which may underlie fast attractiveness judgments.

Implicit emotion regulation deficits in individuals with high schizotypal traits: an ERP study

Schizotypy is associated with poor emotion regulation that is thought to contribute to the development of psychotic symptoms and to indicate a predisposition to schizophrenia. Having focused primarily on the relationship between schizotypy and explicit emotion regulation, existing studies have, until now, neglected to acknowledge the potentially important role of implicit emotion regulation. Our aim in the current study was to investigate implicit emotion regulation deficits in schizotypy. To this end, we used a newly developed Priming-Identification (PI) ERP paradigm, consisting of a priming phase and an emotion identification phase, to test 30 individuals with schizotypy and 30 healthy controls while also acquiring EEG data. During the priming phase, we aimed to manipulate emotion regulation goals (i.e., to bring about an intended emotional state) by presenting a category of words related to emotion regulation alongside a category of control words. Associated brain responses occurring during the subsequent stage were indexed according to three ERP components: N170, early posterior negativity (EPN) and late positive potential (LPP). Results showed that, in the control group, priming words associated with emotion regulation led to enhancements in the early N170 amplitude and the middle EPN during expression identification. The same pattern was not observed in the schizotypy group. In summary, our results suggest the presence of deficits in the early and middle stages of the implicit emotion regulation process among individuals with high schizotypal traits.

The Modulation of Spatial Working Memory by Emotional Stickers and Facial Expressions

This article aims to investigate the interaction effects of emotional valence (negative, positive) and stimulus type (sticker, face) on attention allocation and information retrieval in spatial working memory (WM). The difference in recognition of emotional faces and stickers was also further explored. Using a high-resolution event-related potential (ERP) technique, a time-locked delayed matching-to-sample task (DMST) was employed that allowed separate investigations of target, delay, and probe phases. Twenty-two subjects participated in our experiment. The results indicated that negative face can catch early attention in information encoding, which was indicated by the augmentation of the attention-related P200 amplitude. In the delay phase, the N170 component represents facial specificity and showed a negative bias against stickers. For information retrieval, the increase in the emotion-related late positive component (LPC) showed that positive emotion could damage spatial WM and consume more cognitive resources. Moreover, stickers have the ability to catch an individual’s attention throughout the whole course of spatial WM with larger amplitudes of the attention-related P200, the negative slow wave (NSW), and the LPC. These findings highlight the role of stickers in different phases of spatial WM and provide new viewpoints for WM research on mental patients.

Effects of working memory training on EEG, cognitive performance, and self-report indices potentially relevant for social anxiety

Social anxiety (SA) is quite common and associated with multiple comorbidities. Here, we examined the effects of working memory (WM) training on various indices potentially related to SA. Pre-selected university students with elevated self-reported SA symptoms were assigned to a WM training (n = 21) or an active control treatment condition (n = 21). Pre- and post-treatment assessments were made using questionnaires related to (social) anxiety and depression, and tasks measuring WM, interference control, and attentional biases towards, and event-related potentials (ERPs) elicited by, angry faces. The training enhanced WM transfer task performance, reduced SA symptoms, and changed the amplitude of the P1, N170, P2, and N2 ERP components. However, the latter changes did not mediate the effect of WM training on SA symptoms. These data provide preliminary evidence of the usefulness of WM trainings to reduce potential indices of SA, but further research is necessary to unravel the causal relation among these indices.

Task Demands Modulate Effects of Threatening Faces on Early Perceptual Encoding

The threat capture hypothesis states that threatening stimuli are automatically processed with higher priority than non-threatening stimuli, irrespective of observer intentions or focus of attention. We evaluated the threat capture hypothesis with respect to the early perceptual stages of face processing. We focused on an electrophysiological marker of face processing (the lateralized N170) in response to neutral, happy, and angry facial expressions displayed in competition with a non-face stimulus (a house). We evaluated how effects of facial expression on the lateralized N170 were modulated by task demands. In the pixel task, participants were required to identify the gender of the face, which made the face task-relevant and entailed structural encoding of the face stimulus. In the pixel task, participants identified the location of a missing pixel in the fixation cross, which made the face task-irrelevant and placed it outside the focus of attention. When faces were relevant, the lateralized N170 to angry faces was enhanced compared to happy and neutral faces. When faces were irrelevant, facial expression had no effect. These results reveal the critical role of task demands on the preference for threatening faces, indicating that top-down, voluntary processing modulates the prioritization of threat.

Double-checking emotions: Valence and emotion category in contextual integration of facial expressions of emotion

Faces showing happy, angry or fearful expressions were presented in emotionally congruent or incongruent situational contexts (short sentences describing events that would usually provoke happiness, anger or fear). The participants were assigned the task of judging whether the expression was appropriate or not to the context (congruency judgment task). Effects of emotional congruency were observed at both the behavioral and electrophysiological levels. Behavioral results showed evidence of congruency effects based on specific emotion content (e.g., less accurate and slower responses to fear faces in angry contexts). Event-related-potentials (ERP) results also showed emotional congruency effects at different post-stimulus onset latencies, beginning with the face-sensitive N170 component. An effect of emotional congruency was also shown on the N400 component that is typically sensitive to semantic congruency. Finally, a late positive potential (LPP), appearing at 450-650 ms post-stimulus onset showed a complex pattern of effects with modulations driven by the different combinations of contexts and target expressions. These results are interpreted in terms of a double process of valence and emotion checking that is supposed to underlie affective processing and contextual integration of facial expressions of emotions.

ERP evidence on how gaze convergence affects social attention

How people process gaze cues from multiple others is an important topic but rarely studied. Our study investigated this question using an adapted gaze cueing paradigm to examine the cueing effect of multiple gazes and its neural correlates. We manipulated gaze directions from two human avatars to be either convergent, created by the two avatars simultaneously averting their gazes to the same direction, or non-convergent, when only one of the two avatars shifted its gaze. Our results showed faster reaction times and larger target-congruency effects following convergent gazes shared by the avatars, compared with the non-convergent gaze condition. These findings complement previous research to demonstrate that observing shared gazes from as few as two persons is sufficient to enhance gaze cueing. Additionally, ERP analyses revealed that (1) convergent gazes evoked both left and right hemisphere N170, while non-convergent gazes evoked N170 mainly in the hemisphere contralateral to the cueing face; (2) effects of target congruency on target-locked N1 and P3 were modulated by gaze convergence. These findings shed light on temporal features of the processing of multi-gaze cues.

Tuning Attention to Object Categories: Spatially Global Effects of Attention to Faces in Visual Processing

Feature-based attention is known to enhance visual processing globally across the visual field, even at task-irrelevant locations. Here, we asked whether attention to object categories, in particular faces, shows similar location-independent tuning. Using EEG, we measured the face-selective N170 component of the EEG signal to examine neural responses to faces at task-irrelevant locations while participants attended to faces at another task-relevant location. Across two experiments, we found that visual processing of faces was amplified at task-irrelevant locations when participants attended to faces relative to when participants attended to either buildings or scrambled face parts. The fact that we see this enhancement with the N170 suggests that these attentional effects occur at the earliest stage of face processing. Two additional behavioral experiments showed that it is easier to attend to the same object category across the visual field relative to two distinct categories, consistent with object-based attention spreading globally. Together, these results suggest that attention to high-level object categories shows similar spatially global effects on visual processing as attention to simple, individual, low-level features.

ERP Perspective Analysis of PSS Component and Decision-Making

This paper has developed a neuromarketing framework measuring the relationship between products and services in product–service systems (PSSs), particularly regarding its impact on PSS decision making. We divided the PSSs into different levels of product and service combinations in order to identify the impact of the various elements in PSS on decision making, particularly the key factor that induces significant variation in the purchase rate. The experiments showed the neural mechanisms behind the value perception of PSSs; this has been indicated by the appearance of N170, which is related to the cognition processing of familiarity and similarity. It is concluded that the perceived value of the product-oriented PSS is mainly determined by the product attribute, as the promotional effect of service has been clarified. The results explain the psychological and neurological activities that take place when consumers are browsing product–service bundles, which may help corporations better understand the relationships among the components in product–service bundles, providing insight for PSS innovation and service design.

Attenuated Face Processing during Mind Wandering

Mind wandering (MW) has been recently investigated in many studies. It has been suggested that, during MW, processing of perceptual stimuli is attenuated in favor of internal thoughts, a phenomenon referred to as perceptual decoupling. Perceptual decoupling has been investigated in ERP studies, which have used relatively simple perceptual stimuli, yet it remains unclear if MW can impact the perceptual processing of complex stimuli with real-world relevance. Here, we investigated the impact of MW on behavioral and neural responses to faces. Thirty-six participants completed a novel sustained attention to response task with faces. They were asked to respond to upright faces (nontargets) and withhold responses to inverted faces (targets) and to report intermittently if they were “On task” or “Off task.” Behavioral analyses revealed greater intraindividual coefficient of variation for nontarget faces preceding Off task versus On task. ERP analyses focused primarily on the N170 component associated with face processing but also included the P1 and P3 components. The results revealed attenuated amplitudes to nontarget faces preceding Off task versus On task for the N170, but not for the P3 or P1. These findings suggest decoupled visual processing of faces during MW, which has implications for social neuroscience research.

Similar distraction, but differential suppression, for faces and non-face objects: Evidence from behaviour and event-related potentials

In everyday life we constantly experience distractions. Some distractors might be more distracting than others, for example the human face, which has been shown to be very efficient in attracting attention. Here, we employed the irrelevant-distractor paradigm (Forster & Lavie, 2016) to measure behavioural and neural distraction by completely irrelevant faces or non-faces (cars), while participants performed a letter search task that was more (high-load) or less (low-load) demanding. Under low load conditions, faces and cars equally slowed responses on trials with distractors as compared to those without. In high load conditions, neither faces nor cars were distracting. However, event-related potentials revealed larger face-sensitive N170 responses to faces than cars under both load conditions, suggesting that early face-specific processing is present even under high load. A subsequent Pd modulation between 200 and 300 ms contralateral to the distractor position, which has been linked to the active top-down suppression of lateral distractors (Hickey et al., 2009) was stronger for faces compared to cars. Overall, the EEG data indicate early face-specific processes to irrelevant faces irrespective of attentional load, coupled with stronger top-down suppression for faces. Together, these processes might reduce the influence of irrelevant face distractors on behavioural performance.

Impairments of emotional face processing in schizophrenia patients: Evidence from P100, N170 and P300 ERP components in a sample of auditory hallucinators

Patients with schizophrenia show impaired face and emotional expression processing that may be due to early perceptual deficits or late impairments in higher-order emotional facial recognition. This study examined event-related potentials (ERPs) in 23 patients with schizophrenia who experience auditory hallucinations and 19 healthy controls. EEG activity was recorded from 32 scalp sites positioned according to the 10-10 placement system. Linked left and right electrodes at the mastoids served as the reference. The P100, N170 and P300 were measured during an emotional facial identification task, which included neutral, joyful, sad, angry and fearful facial expressions and non-face stimuli (chairs). P100 was measured at O_1/2 and P_7/8. N170 was measured at P_7/8. P300 was measured at P_z. Patients with schizophrenia were slower at identifying all facial expressions, including neutral ones. They also showed less positive P100 amplitude to sad, angry and fearful facial expressions. N170 amplitudes were smaller in patients in response to neutral, joyful, sad, angry, and fearful facial expression. Patients showed less positive P300 mean amplitudes to all facial expressions, including neutral ones. Within-group comparisons showed that patients exhibited a different pattern of ERP modulation across facial expressions than controls for P100 and N170, but not for P300. Our findings are compatible with the idea that behavioural and electrophysiological face-processing deficits in schizophrenia arise from early-stage deficits in visual processing.

One versus two eyes makes a difference! Early face perception is modulated by featural fixation and feature context

The N170 event-related potential component is an early marker of face perception that is particularly sensitive to isolated eye regions and to eye fixations within a face. Here, this eye sensitivity was tested further by measuring the N170 to isolated facial features and to the same features fixated within a face, using a gaze-contingent procedure. The neural response to single isolated eyes and eye regions (two eyes) was also compared. Pixel intensity and contrast were controlled at the global (image) and local (featural) levels. Consistent with previous findings, larger N170 amplitudes were elicited when the left or right eye was fixated within a face, compared to the mouth or nose, demonstrating that the N170 eye sensitivity reflects higher-order perceptual processes and not merely low-level perceptual effects. The N170 was also largest and most delayed for isolated features, compared to equivalent fixations within a face. Specifically, mouth fixation yielded the largest amplitude difference, and nose fixation yielded the largest latency difference between these two contexts, suggesting the N170 may reflect a complex interplay between holistic and featural processes. Critically, eye regions elicited consistently larger and shorter N170 responses compared to single eyes, with enhanced responses for contralateral eye content, irrespective of eye or nasion fixation. These results confirm the importance of the eyes in early face perception, and provide novel evidence of an increased sensitivity to the presence of two symmetric eyes compared to only one eye, consistent with a neural eye region detector rather than an eye detector per se.

Enhancement of face-sensitive ERPs in older adults induced by face recognition training

A common cognitive problem reported by older people is compromised face recognition, which is often paralleled by age-related changes in face-sensitive and memory-related components in event-related brain potentials (ERPs). We developed a new training using photorealistic caricatures based on evidence that caricatures are beneficial for people with compromised face processing. Twenty-four older participants (62-75 yrs, 13 female) completed 12 training sessions (3 per week, 60 min each) and 24 older participants (61-76 yrs, 12 female) acted as controls. Before and after training (or waiting), participants took part in a diagnostic test battery for face processing abilities, and in ERP experiments on face learning and recognition. Although performance improvements during the training provided little evidence for generalization to other face processing tasks, ERPs showed substantial training-related enhancements of face-sensitive ERPs. Specifically, we observed marked increases of the N170, P200 and N250 components, which may indicate training-induced enhancement of face detection and activation of identity-specific representations. Thus, neuronal correlates of face processing are plastic in older age, and can be modulated by caricature training.

The influence of behavioral relevance on the processing of global scene properties: An ERP study

Recent work studying the temporal dynamics of visual scene processing (Harel et al., 2016) has found that global scene properties (GSPs) modulate the amplitude of early Event-Related Potentials (ERPs). It is still not clear, however, to what extent the processing of these GSPs is influenced by their behavioral relevance, determined by the goals of the observer. To address this question, we investigated how behavioral relevance, operationalized by the task context impacts the electrophysiological responses to GSPs. In a set of two experiments we recorded ERPs while participants viewed images of real-world scenes, varying along two GSPs, naturalness (manmade/natural) and spatial expanse (open/closed). In Experiment 1, very little attention to scene content was required as participants viewed the scenes while performing an orthogonal fixation-cross task. In Experiment 2 participants saw the same scenes but now had to actively categorize them, based either on their naturalness or spatial expense. We found that task context had very little impact on the early ERP responses to the naturalness and spatial expanse of the scenes: P1, N1, and P2 could distinguish between open and closed scenes and between manmade and natural scenes across both experiments. Further, the specific effects of naturalness and spatial expanse on the ERP components were largely unaffected by their relevance for the task. A task effect was found at the N1 and P2 level, but this effect was manifest across all scene dimensions, indicating a general effect rather than an interaction between task context and GSPs. Together, these findings suggest that the extraction of global scene information reflected in the early ERP components is rapid and very little influenced by top-down observer-based goals.

Mental imagery of face enhances face-sensitive event-related potentials to ambiguous visual stimuli

Visual mental imagery forms mental representations of visual objects when correspondent stimuli are absent and shares some characters with visual perception. Both the vertex-positive-potential (VPP) and N170 components of event-related potentials (ERPs) to visual stimuli have a remarkable preference to faces. This study investigated whether visual mental imagery modulates the face-sensitive VPP and/or N170 components. The results showed that with significantly larger amplitudes under the face-imagery condition than the house-imagery condition, the VPP and P2 responses, but not the N170 component, were elicited by phase-randomized ambiguous stimuli. Thus, the brain substrates underlying VPP are not completely identical to those underlying N170, and the VPP/P2 manifestation of the category selectivity in imagery probably reflects an integration of top-down mental imagery signals (from the prefrontal cortex) and bottom-up perception signals (from the early visual cortex) in the occipito-temporal cortex where VPP and P2 originate.

Dissociating Attention Effects from Categorical Perception with ERP Functional Microstates

When faces appear in our visual environment we naturally attend to them, possibly to the detriment of other visual information. Evidence from behavioural studies suggests that faces capture attention because they are more salient than other types of visual stimuli, reflecting a category-dependent modulation of attention. By contrast, neuroimaging data has led to a domain-specific account of face perception that rules out the direct contribution of attention, suggesting a dedicated neural network for face perception. Here we sought to dissociate effects of attention from categorical perception using Event Related Potentials. Participants viewed physically matched face and butterfly images, with each category acting as a target stimulus during different blocks in an oddball paradigm. Using a data-driven approach based on functional microstates, we show that the locus of endogenous attention effects with ERPs occurs in the N1 time range. Earlier categorical effects were also found around the level of the P1, reflecting either an exogenous increase in attention towards face stimuli, or a putative face-selective measure. Both category and attention effects were dissociable from one another hinting at the role that faces may play in early capturing of attention before top-down control of attention is observed. Our data support the conclusion that certain object categories, in this experiment, faces, may capture attention before top-down voluntary control of attention is initiated.

Neural Signatures of Conscious Face Perception in an Inattentional Blindness Paradigm

Previous studies suggest that early stages of face-specific processing are performed preattentively and unconsciously, whereas conscious perception emerges with late-stage (>300 ms) neuronal activity. A conflicting view, however, posits that attention is necessary for face-specific processing and that early-to-mid latency neural responses (∼ 100-300 ms) correspond more closely with perceptual awareness. The current study capitalized on a recently developed method for manipulating attention and conscious perception during EEG recording (modified inattentional blindness paradigm) and used face stimuli that elicit a well known marker of early face processing, the N170 event-related potential (ERP). In Phase 1 of the experiment, subjects performed a demanding distracter task while line drawings of faces and matched control stimuli were presented in the center of their view. When queried, half of the subjects reported no awareness of the faces and were deemed inattentionally blind. In Phase 2, subjects performed the same distracter task, but now consciously perceived the face stimuli due to the intervening questioning. In Phase 3, subjects performed a discrimination task on the faces. Two primary contrasts were made: aware versus unaware (equally task irrelevant) and task-relevant versus task-irrelevant (equally aware). The N170 and a subsequent ERP component, the visual awareness negativity (∼ 260-300 ms), were absent during inattentional blindness and present in the aware conditions. The P3b (> 300 ms) was absent for task-irrelevant faces, even when consciously perceived, and present only when the faces were task relevant. These results inform contemporary theories of conscious face perception in particular and visual attention and perceptual awareness in general.

Event-related potentials in response to cheating and cooperation in a social dilemma game

A sequential prisoner's dilemma game was combined with psychophysiological measures to examine the cognitive underpinnings of reciprocal exchange. Participants played four rounds of the game with partners who either cooperated or cheated. In a control condition, the partners' faces were shown, but no interaction took place. The partners' behaviors were consistent in the first three rounds of the game, but in the last round some of the partners unexpectedly changed strategies. In the first round of the game, the feedback about a partner's decision elicited a feedback P300, which was more pronounced for cooperation and cheating in comparison to the control condition, but did not vary as a function of feedback valence. In the last round, both the feedback negativity and the feedback P300 were sensitive to expectancy violations. There was no consistent evidence for a negativity bias, that is, enhanced allocation of attention to feedback about another person's cheating in comparison to feedback about another person's cooperation. Instead, participants focused on both positive and negative information, and flexibly adjusted their processing biases to the diagnosticity of the information. This conclusion was corroborated by the ERP correlates of memory retrieval. Successful retrieval of a partner's reputation was associated with an anterior positivity between 400 and 600 ms after face onset. This anterior positivity was more pronounced for both cooperator and cheater faces in comparison to control faces. The results suggest that it is not the negativity of social information, but rather its motivational and behavioral relevance that determines its processing.

Face recognition in schizophrenia disorder: A comprehensive review of behavioral, neuroimaging and neurophysiological studies

Facial emotion processing has been extensively studied in schizophrenia patients while general face processing has received less attention. The already published reviews do not address the current scientific literature in a complete manner. Therefore, here we tried to answer some questions that remain to be clarified, particularly: are the non-emotional aspects of facial processing in fact impaired in schizophrenia patients? At the behavioral level, our key conclusions are that visual perception deficit in schizophrenia patients: are not specific to faces; are most often present when the cognitive (e.g. attention) and perceptual demands of the tasks are important; and seems to worsen with the illness chronification. Although, currently evidence suggests impaired second order configural processing, more studies are necessary to determine whether or not holistic processing is impaired in schizophrenia patients. Neural and neurophysiological evidence suggests impaired earlier levels of visual processing, which might involve the deficits in interaction of the magnocellular and parvocellular pathways impacting on further processing. These deficits seem to be present even before the disorder out-set. Although evidence suggests that this deficit may be not specific to faces, further evidence on this question is necessary, in particularly more ecological studies including context and body processing.

Configural and featural face processing are differently modulated by attentional resources at early stages: an event-related potential study with rapid serial visual presentation

It is widely reported that face recognition relies on two dissociable mechanisms, the featural and the configural processing. However, it is unclear whether these two processing types involve different neural mechanisms and are differently modulated by attentional resources. Using the attentional blink (AB) paradigm, we aimed to investigate the effect of attentional resources on configural and featural face processing by recording event-related potentials (ERPs). The amount of attentional resources was manipulated as deficient or sufficient by presenting the second target (T2) in or out of the AB period, respectively. We found that in addition to a traditional P3 attention effect, the amplitude of N170/VPP to the T2 stimuli was also sensitive to attentional resources, suggesting that attention affects face processing at an earlier perceptual processing stage. More importantly, configural face processing elicited a larger posterior P1 compared to featural face processing, but only when the attentional resources were sufficient. In contrast, the anterior N1 was larger for configural relative to featural face processing only when the attentional resources were deficient. These results suggest that early stages of configural and featural face processing are differently modulated by attentional resources, possibly with different underlying mechanisms.

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

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

Modulation of the N170 adaptation profile by higher level factors

Event-related potentials provide strong evidence for a face-specific process that peaks at about 170 ms following stimulus onset--the N170 effect. The N170 has been shown to be sensitive to adaptation, reflected in an amplitude reduction by repeated face presentation, which is usually considered to be driven by bottom-up processes. Here we investigated whether the N170 adaptation profile can be modulated by top-down factors aiming at holistic or feature-based processing. Adaptor stimuli were Mooney faces, isolated facial features (eyes or mouths), or houses. Target faces required either a gender decision (holistic task), or a decision on a facial feature (detail task). We observed an intricate crossover interaction pattern, reflected in opposite effects on adaptation to Mooney faces and eyes as compared to mouth conditions. These findings provide evidence that adaptation effects can be modulated by top-down processes.

The impact of task relevance and degree of distraction on stimulus processing

Background

The impact of task relevance on event-related potential amplitudes of early visual processing was previously demonstrated. Study designs, however, differ greatly, not allowing simultaneous investigation of how both degree of distraction and task relevance influence processing variations. In our study, we combined different features of previous tasks. We used a modified 1-back task in which task relevant and task irrelevant stimuli were alternately presented. The task irrelevant stimuli could be from the same or from a different category as the task relevant stimuli, thereby producing high and low distracting task irrelevant stimuli. In addition, the paradigm comprised a passive viewing condition. Thus, our paradigm enabled us to compare the processing of task relevant stimuli, task irrelevant stimuli with differing degrees of distraction, and passively viewed stimuli. EEG data from twenty participants was collected and mean P100 and N170 amplitudes were analyzed. Furthermore, a potential connection of stimulus processing and symptoms of attention deficit hyperactivity disorder (ADHD) was investigated.

Results

Our results show a modulation of peak N170 amplitudes by task relevance. N170 amplitudes to task relevant stimuli were significantly higher than to high distracting task irrelevant or passively viewed stimuli. In addition, amplitudes to low distracting task irrelevant stimuli were significantly higher than to high distracting stimuli. N170 amplitudes to passively viewed stimuli were not significantly different from either kind of task irrelevant stimuli. Participants with more symptoms of hyperactivity and impulsivity showed decreased N170 amplitudes across all task conditions. On a behavioral level, lower N170 enhancement efficiency was significantly correlated with false alarm responses.

Conclusions

Our results point to a processing enhancement of task relevant stimuli. Unlike P100 amplitudes, N170 amplitudes were strongly influenced by enhancement and enhancement efficiency seemed to have direct behavioral consequences. These findings have potential implications for models of clinical disorders affecting selective attention, especially ADHD.

The male advantage in child facial resemblance detection: behavioral and ERP evidence

Males have been suggested to have advantages over females in reactions to child facial resemblance, which reflects the evolutionary pressure on males to solve the adaptive paternal uncertainty problem and to identify biological offspring. However, previous studies showed inconsistent results and the male advantage in child facial resemblance perception, as a kin detection mechanism, is still unclear. Here, we investigated the behavioral and brain mechanisms underlying the self-resembling faces processing and how it interacts with sex and age using event-related potential (ERP) technique. The results showed a stable male advantage in self-resembling child faces processing, such that males have higher detectability to self-resembling child faces than females. For ERP results, males showed smaller N2 and larger late positive component (LPC) amplitudes for self-resembling child faces, which may reflect face-matching and self-referential processing in kin detection, respectively. Further source analysis showed that the N2 component and LPC were originated from the anterior cingulate cortex and medial frontal gyrus, respectively. Our results support the male advantage in self-resembling child detection and further indicate that such distinctions can be found in both early and late processing stages in the brain at different regions.

Reward modulates the neural dynamics of early visual category processing

Converging evidence suggests that visual brain regions are part of a widespread network that signals forthcoming reward. However, the precise temporal dynamics underlying the interaction between reward and visual information processing remain unclear. To further investigate this issue, we used magnetoencephalography (MEG) in combination with two versions of a face/scene discrimination task followed by a recognition memory test. In experiment 1, the distinction between faces and scenes was associated with monetary reward prospect, whereas in experiment 2 subjects distinguished between both categories in the absence of reward. In both experiments characteristic neural category effects (i.e., differences between faces and scenes) were observed in the event-related magnetic fields (ERF) at ~100 ms (M100) and ~170 ms (M170) after stimulus onset. Importantly, both ERF components (M100 and M170) were amplified in the context of reward (i.e., experiment 1) and this interaction could be source localized to the lateral occipital cortex (~100 ms) and fusiform gyrus (~170 ms). Furthermore, neural effects of reward prediction emerged over frontal sensors at ~300 ms after stimulus onset which reliably correlated with subsequent recognition memory performance. These results demonstrate that reward motivation can modulate early neural computations of complex visual information, possibly by tuning sensory neurons within the visual cortex.

Modeling Single-Trial ERP Reveals Modulation of Bottom-Up Face Visual Processing by Top-Down Task Constraints (in Some Subjects)

We studied how task constraints modulate the relationship between single-trial event-related potentials (ERPs) and image noise. Thirteen subjects performed two interleaved tasks: on different blocks, they saw the same stimuli, but they discriminated either between two faces or between two colors. Stimuli were two pictures of red or green faces that contained from 10 to 80% of phase noise, with 10% increments. Behavioral accuracy followed a noise dependent sigmoid in the identity task but was high and independent of noise level in the color task. EEG data recorded concurrently were analyzed using a single-trial ANCOVA: we assessed how changes in task constraints modulated ERP noise sensitivity while regressing out the main ERP differences due to identity, color, and task. Single-trial ERP sensitivity to image phase noise started at about 95-110 ms post-stimulus onset. Group analyses showed a significant reduction in noise sensitivity in the color task compared to the identity task from about 140 ms to 300 ms post-stimulus onset. However, statistical analyses in every subject revealed different results: significant task modulation occurred in 8/13 subjects, one showing an increase and seven showing a decrease in noise sensitivity in the color task. Onsets and durations of effects also differed between group and single-trial analyses: at any time point only a maximum of four subjects (31%) showed results consistent with group analyses. We provide detailed results for all 13 subjects, including a shift function analysis that revealed asymmetric task modulations of single-trial ERP distributions. We conclude that, during face processing, bottom-up sensitivity to phase noise can be modulated by top-down task constraints, in a broad window around the P2, at least in some subjects.

Selective attention modulates face-specific induced gamma oscillations recorded from ventral occipitotemporal cortex

EEG studies from subdural electrodes have demonstrated a face-specific event-related potential (face-N200) recorded from human ventral occipitotemporal cortex. The insensitivity of face-N200 to task manipulations has supported the proposal that face-N200 reflects an initial obligatory response to faces. This result stands in striking contrast to results of neuroimaging studies that have demonstrated strong task sensitivity of the fusiform hemodynamic response evoked by faces, and thus has created a paradox in the face perception literature. We recorded field potentials directly from the cortical surface of 16 patients while they selectively attended to faces or houses. Here we report that face-specific gamma activity recorded at face-N200 sites is strongly modulated by selective attention, while face-N200 is not. Our results reconcile prior electrophysiological and hemodynamic studies of face perception, and suggest that attentional modulation of the face response follows an initial phase that is largely insensitive to attention.

Early top-down control of visual processing predicts working memory performance

Selective attention confers a behavioral benefit on both perceptual and working memory (WM) performance, often attributed to top-down modulation of sensory neural processing. However, the direct relationship between early activity modulation in sensory cortices during selective encoding and subsequent WM performance has not been established. To explore the influence of selective attention on WM recognition, we used electroencephalography to study the temporal dynamics of top-down modulation in a selective, delayed-recognition paradigm. Participants were presented with overlapped, "double-exposed" images of faces and natural scenes, and were instructed to either remember the face or the scene while simultaneously ignoring the other stimulus. Here, we present evidence that the degree to which participants modulate the early P100 (97-129 msec) event-related potential during selective stimulus encoding significantly correlates with their subsequent WM recognition. These results contribute to our evolving understanding of the mechanistic overlap between attention and memory.