Perception of static eye gaze direction facilitates subsequent early visual processing

The influence of perceptual load on gaze-induced attentional orienting: The modulation of expectation

Humans tend to focus on others' gaze. Previous studies have shown that the gaze direction of others can induce corresponding attentional orienting. However, gaze cues have typically been presented alone in these studies. It is unclear how gaze cues induce observers' attention in complicated contexts with additional perceptual information. Therefore, the present study investigated gaze-induced attentional orienting at different levels of perceptual load. Results indicated that the attentional effect of the dynamic gaze cue (i.e., GCE: gaze cue effect) emerged under low perceptual load and disappeared under high perceptual load. The absence of GCE could not attribute to perceptual capacity exhaustion. Moreover, the influence of perceptual load on gaze-induced attentional orienting was modulated by individuals' expectation. Specifically, the GCE occurred under high perceptual load when the gaze cue was predictive (with individuals' expectation). These findings provide new evidence on the mode of gaze-induced attentional orienting under different perceptual load conditions.

A Trained Humanoid Robot can Perform Human-Like Crossmodal Social Attention and Conflict Resolution

To enhance human-robot social interaction, it is essential for robots to process multiple social cues in a complex real-world environment. However, incongruency of input information across modalities is inevitable and could be challenging for robots to process. To tackle this challenge, our study adopted the neurorobotic paradigm of crossmodal conflict resolution to make a robot express human-like social attention. A behavioural experiment was conducted on 37 participants for the human study. We designed a round-table meeting scenario with three animated avatars to improve ecological validity. Each avatar wore a medical mask to obscure the facial cues of the nose, mouth, and jaw. The central avatar shifted its eye gaze while the peripheral avatars generated sound. Gaze direction and sound locations were either spatially congruent or incongruent. We observed that the central avatar's dynamic gaze could trigger crossmodal social attention responses. In particular, human performance was better under the congruent audio-visual condition than the incongruent condition. Our saliency prediction model was trained to detect social cues, predict audio-visual saliency, and attend selectively for the robot study. After mounting the trained model on the iCub, the robot was exposed to laboratory conditions similar to the human experiment. While the human performance was overall superior, our trained model demonstrated that it could replicate attention responses similar to humans.

Prediction of state anxiety by machine learning applied to photoplethysmography data

Background

As the human behavior is influenced by both cognition and emotion, affective computing plays a central role in human-machine interaction. Algorithms for emotions recognition are usually based on behavioral analysis or on physiological measurements (e.g., heart rate, blood pressure). Among these physiological signals, pulse wave propagation in the circulatory tree can be assessed through photoplethysmography (PPG), a non-invasive optical technique. Since pulse wave characteristics are influenced by the cardiovascular status, which is affected by the autonomic nervous activity and hence by the psychophysiological state, PPG might encode information about emotional conditions. The capability of a multivariate data-driven approach to estimate state anxiety (SA) of healthy participants from PPG features acquired on the brachial and radial artery was investigated.

Methods

The machine learning method was based on General Linear Model and supervised learning. PPG was measured employing a custom-made system and SA of the participants was assessed through the State-Trait Anxiety Inventory (STAI-Y) test.

Results

A leave-one-out cross-validation framework showed a good correlation between STAI-Y score and the SA predicted by the machine learning algorithm (r = 0.81; p = 1.87∙10⁻⁹). The preliminary results suggested that PPG can be a promising tool for emotions recognition, convenient for human-machine interaction applications.

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.

The role of the motion cue in the dynamic gaze-cueing effect: A study of the lateralized ERPs

When face was inverted, dynamic gaze cues could still effectively direct attention despite the disruption of configural face processing, but the static gaze cues could not. The present study investigated the role of the motion cue in the dynamic Gaze-Cueing Effect (GCE). With schematic and real faces, we employed the gaze-cueing paradigm to examine the differences among three kinds of cues (static gaze cue, dynamic gaze cue and motion cue) based on behavioral results and event-related potentials. Behavioral results revealed significant GCE in all conditions. In the schematic face group, the motion cue (two symmetrical dots shifting slightly to the side) induced a significantly smaller GCE than the dynamic gaze cues (two symmetrical dots moving within a rounded circle), while in the real face group, the motion cue (that is, the inverted-face gaze cue) remained a strong GCE compared with other conditions. With regard to the ERP results, we found the early directing attention negativity (EDAN), which was sensitive to voluntary cues (e.g. arrow cue) rather than gaze cue, in the schematic motion cue condition, but not in the inverted-face gaze cue condition. We supposed that the motion cue (real face) could activate the configural face processing even when the face is inverted. This finding supported that EDAN reflected a cue-triggered attention shift.

RT Slowing to Valid Cues on a Reflexive Attention Task in Children and Young Adults

Peripheral cueing tasks can be used to measure reflexive (automatic) attention. In these tasks, increases in response time or RT (costs) typically follow contralateral (invalid) cues as attention must move from the location of the cue to the target. Reductions in RT (benefits) to a target typically follow ipsilateral (valid) cues because the cue draws attention to where the target will appear. Two exceptions to RT benefits are inhibition of return (IOR) and masking. IOR is the tendency to respond slower to targets that appear in locations attended within the last 200–2000 ms. Masking occurs when the visibility of a target is blocked by another stimulus (e.g., the cue). Herein, we describe two experiments, both using a modified Posner task with “earth rockets” as cues and “alien spaceships” as targets. Cues were equally likely to appear on the left or right side of a display following targets. Participants were instructed to press a left or right key corresponding to a left or right target. In Experiment 1, we obtained data from 203 children (10.58–16.55 years old). We discovered unexpected costs following cues that typically provide RT benefits. In Experiment 2, we explored IOR, masking, and age differences in the occurrence of these costs. We manipulated the cue-target temporal distance (“stimulus onset asynchrony” or SOA) to explore IOR and the cue-target spatial distance to explore masking. We also considered a wider age range. Sixty-three children and 41 young adults participated. Experiment 2 revealed a three-way interaction between SOA, spatial distance, and age. At the shorter SOA (100 ms) and moderate spatial distance, unexpected costs followed valid cues for younger children (7.07–10.15 years old). These costs also occurred in young adults (18.00–23.02 years old) following far distance cues at this SOA. At the longer SOA (200 ms), these costs followed moderate and far cues for younger children and near cues for young adults. Older children (10.31–14.92 years) did not have unexpected costs. We explain the findings in terms of masking, IOR, and possible developmental mechanisms.

Saccades and smooth pursuit eye movements trigger equivalent gaze-cued orienting effects

Research has established that a perceived eye gaze produces a concomitant shift in a viewer's spatial attention in the direction of that gaze. The two experiments reported here investigate the extent to which the nature of the eye movement made by the gazer contributes to this orienting effect. On each trial in these experiments, participants were asked to make a speeded response to a target that could appear in a location toward which a centrally presented face had just gazed (a cued target) or in a location that was not the recipient of a gaze (an uncued target). The gaze cues consisted of either fast saccadic eye movements or slower smooth pursuit movements. Cued targets were responded to faster than uncued targets, and this gaze-cued orienting effect was found to be equivalent for each type of gaze shift both when the gazes were un-predictive of target location (Experiment 1) and counterpredictive of target location (Experiment 2). The results offer no support for the hypothesis that motion speed modulates gaze-cued orienting. However, they do suggest that motion of the eyes per se, regardless of the type of movement, may be sufficient to trigger an orienting effect.

Human cortical activity evoked by contextual processing in attentional orienting

The ability to assess another person’s direction of attention is paramount in social communication, many studies have reported a similar pattern between gaze and arrow cues in attention orienting. Neuroimaging research has also demonstrated no qualitative differences in attention to gaze and arrow cues. However, these studies were implemented under simple experiment conditions. Researchers have highlighted the importance of contextual processing (i.e., the semantic congruence between cue and target) in attentional orienting, showing that attentional orienting by social gaze or arrow cues could be modulated through contextual processing. Here, we examine the neural activity of attentional orienting by gaze and arrow cues in response to contextual processing using functional magnetic resonance imaging. The results demonstrated that the influence of neural activity through contextual processing to attentional orienting occurred under invalid conditions (when the cue and target were incongruent versus congruent) in the ventral frontoparietal network, although we did not identify any differences in the neural substrates of attentional orienting in contextual processing between gaze and arrow cues. These results support behavioural data of attentional orienting modulated by contextual processing based on the neurocognitive architecture.

The Role of Global and Local Visual Information during Gaze-Cued Orienting of Attention

Gaze direction is an important social communication tool. Global and local visual information are known to play specific roles in processing socially relevant information from a face. The current study investigated whether global visual information has a primary role during gaze-cued orienting of attention and, as such, may influence quality of interaction. Adults performed a gaze-cueing task in which a centrally presented face cued (valid or invalid) the location of a peripheral target through a gaze shift. We measured brain activity (electroencephalography) towards the cue and target and behavioral responses (manual and saccadic reaction times) towards the target. The faces contained global (i.e. lower spatial frequencies), local (i.e. higher spatial frequencies), or a selection of both global and local (i.e. mid-band spatial frequencies) visual information. We found a gaze cue-validity effect (i.e. valid versus invalid), but no interaction effects with spatial frequency content. Furthermore, behavioral responses towards the target were in all cue conditions slower when lower spatial frequencies were not present in the gaze cue. These results suggest that whereas gaze-cued orienting of attention can be driven by both global and local visual information, global visual information determines the speed of behavioral responses towards other entities appearing in the surrounding of gaze cue stimuli.

The effect of Ramadan fasting on spatial attention through emotional stimuli

Fasting can influence psychological and mental states. In the current study, the effect of periodical fasting on the process of emotion through gazed facial expression as a realistic multisource of social information was investigated for the first time. The dynamic cue-target task was applied via behavior and event-related potential measurements for 40 participants to reveal the temporal and spatial brain activities – before, during, and after fasting periods. The significance of fasting included several effects. The amplitude of the N1 component decreased over the centroparietal scalp during fasting. Furthermore, the reaction time during the fasting period decreased. The self-measurement of deficit arousal as well as the mood increased during the fasting period. There was a significant contralateral alteration of P1 over occipital area for the happy facial expression stimuli. The significant effect of gazed expression and its interaction with the emotional stimuli was indicated by the amplitude of N1. Furthermore, the findings of the study approved the validity effect as a congruency between gaze and target position, as indicated by the increment of P3 amplitude over centroparietal area as well as slower reaction time from behavioral response data during incongruency or invalid condition between gaze and target position compared with those during valid condition. Results of this study proved that attention to facial expression stimuli as a kind of communicative social signal was affected by fasting. Also, fasting improved the mood of practitioners. Moreover, findings from the behavioral and event-related potential data analyses indicated that the neural dynamics of facial emotion are processed faster than that of gazing, as the participants tended to react faster and prefer to relay on the type of facial emotions than to gaze direction while doing the task. Because of happy facial expression stimuli, right hemisphere activation was more than that of the left hemisphere. It indicated the consistency of the emotional lateralization concept rather than the valence concept of emotional processing.

Complexities of emotional responses to social and non-social affective stimuli in schizophrenia

BACKGROUND

Adaptive emotional responses are important in interpersonal relationships. We investigated self-reported emotional experience, physiological reactivity, and micro-facial expressivity in relation to the social nature of stimuli in individuals with schizophrenia (SZ).

METHOD

Galvanic skin response (GSR) and facial electromyography (fEMG) were recorded in medicated outpatients with SZ and demographically matched healthy controls (CO) while they viewed social and non-social images from the International Affective Pictures System. Participants rated the valence and arousal, and selected a label for experienced emotions. Symptom severity in the SZ and psychometric schizotypy in CO were assessed.

RESULTS

The two groups did not differ in their labeling of the emotions evoked by the stimuli, but individuals with SZ were more positive in their valence ratings. Although self-reported arousal was similar in both groups, mean GSR was greater in SZ, suggesting differential awareness, or calibration of internal states. Both groups reported social images to be more arousing than non-social images but their physiological responses to non-social vs. social images were different. Self-reported arousal to neutral social images was correlated with positive symptoms in SZ. Negative symptoms in SZ and disorganized schizotypy in CO were associated with reduced mean fEMG. Greater corrugator mean fEMG activity for positive images in SZ indicates valence-incongruent facial expressions.

CONCLUSION

The patterns of emotional responses differed between the two groups. While both groups were in broad agreement in self-reported arousal and emotion labels, their mean GSR, and fEMG correlates of emotion diverged in relation to the social nature of the stimuli and clinical measures. Importantly, these results suggest disrupted self awareness of internal states in SZ and underscore the complexities of emotion processing in health and disease.

Autistic traits influence gaze-oriented attention to happy but not fearful faces

The relationship between autistic traits and gaze-oriented attention to fearful and happy faces was investigated at the behavioral and neuronal levels. Upright and inverted dynamic face stimuli were used in a gaze-cueing paradigm while event related potentials (ERPs) were recorded. Participants responded faster to gazed-at than to non-gazed-at targets, and this gaze orienting effect (GOE) diminished with inversion, suggesting it relies on facial configuration. It was also larger for fearful than happy faces but only in participants with high autism-spectrum quotient (AQ) scores. While the GOE to fearful faces was of similar magnitude regardless of AQ scores, a diminished GOE to happy faces was found in participants with high AQ scores. At the ERP level, a congruency effect on target-elicited P1 component reflected enhanced visual processing of gazed-at targets. In addition, cue-triggered early directing attention negativity and anterior directing attention negativity reflected, respectively, attention orienting and attention holding at gazed-at locations. These neural markers of spatial attention orienting were not modulated by emotion and were not found in participants with high AQ scores. Together, these findings suggest that autistic traits influence attention orienting to gaze and its modulation by social emotions such as happiness.

Commonalities and differences in the spatiotemporal neural dynamics associated with automatic attentional shifts induced by gaze and arrows

Gaze and arrows automatically trigger attentional shifts. Neuroimaging studies have identified a commonality in the spatial distribution of the neural activation involved in such attentional shifts. However, it remains unknown whether these activations occur with common temporal profiles. To investigate this issue, magnetoencephalography (MEG) was used to evaluate neural activation involved in attentional shifts induced by gaze and arrows. MEG source reconstruction analyses revealed that the superior temporal sulcus and the inferior frontal gyrus were commonly activated after 200ms, in response to directional versus non-directional cues. Regression analyses further revealed that the magnitude of brain activity in these areas and in the bilateral occipital cortex was positively related to the effect of attentional shift on reaction times under both the gaze and the arrow conditions. The results also revealed that some brain regions were activated specifically in response to directional versus non-directional gaze or arrow cues at the 350-400ms time window. These results suggest that the neural mechanisms underlying attentional shifts induced by gaze and arrows share commonalities in their spatial distributions and temporal profiles, with some spatial differences at later time stages.

Fearful, surprised, happy, and angry facial expressions modulate gaze-oriented attention: behavioral and ERP evidence

The impact of emotions on gaze-oriented attention was investigated in non-anxious participants. A neutral face cue with straight gaze was presented, which then averted its gaze to the side while remaining neutral or expressing an emotion (fear/surprise in Exp.1 and anger/happiness in Exp.2). Localization of a subsequent target was faster at the gazed-at location (congruent condition) than at the non-gazed-at location (incongruent condition). This Gaze-Orienting Effect (GOE) was enhanced for fear, surprise, and anger, compared to neutral expressions which did not differ from happy expressions. In addition, Event Related Potentials (ERPs) to the target showed a congruency effect on P1 for fear and surprise and a left lateralized congruency effect on P1 for happy faces, suggesting that target visual processing was also influenced by attention to gaze and emotions. Finally, at cue presentation, early postero-lateral (Early Directing Attention Negativity (EDAN)) and later antero-lateral (Anterior Directing Attention Negativity (ADAN)) attention-related ERP components were observed, reflecting, respectively, the shift of attention and its holding at gazed-at locations. These two components were not modulated by emotions. Together, these findings show that the processing of social signals such as gaze and facial expression interact rather late and in a complex manner to modulate spatial attention.

The role of facial expressions in attention-orienting in adults and infants

Faces convey many signals (i.e., gaze or expressions) essential for interpersonal interaction. We have previously shown that facial expressions of emotion and gaze direction are processed and integrated in specific combinations early in life. These findings open a number of developmental questions and specifically in this paper we address whether such emotional signals may modulate the behavior in a following gaze context. A classic spatial cueing paradigm was used to assess whether different facial expressions may cause differential orienting response times and modulate the visual response to a peripheral target in adults and in 4-month-old infants. Results showed that both adults and infants oriented towards a peripheral target when a central face was gazing in the direction of the target location. However, in adults this effect occurred regardless of the facial expression displayed by the face. In contrast, in infants, the emotional facial expressions used, at least in the current study, did not facilitate the attention shift but tended to hold infants’ attention.

Watch out! Magnetoencephalographic evidence for early modulation of attention orienting by fearful gaze cueing

Others’ gaze and emotional facial expression are important cues for the process of attention orienting. Here, we investigated with magnetoencephalography (MEG) whether the combination of averted gaze and fearful expression may elicit a selectively early effect of attention orienting on the brain responses to targets. We used the direction of gaze of centrally presented fearful and happy faces as the spatial attention orienting cue in a Posner-like paradigm where the subjects had to detect a target checkerboard presented at gazed-at (valid trials) or non gazed-at (invalid trials) locations of the screen. We showed that the combination of averted gaze and fearful expression resulted in a very early attention orienting effect in the form of additional parietal activity between 55 and 70 ms for the valid versus invalid targets following fearful gaze cues. No such effect was obtained for the targets following happy gaze cues. This early cue-target validity effect selective of fearful gaze cues involved the left superior parietal region and the left lateral middle occipital region. These findings provide the first evidence for an effect of attention orienting induced by fearful gaze in the time range of C1. In doing so, they demonstrate the selective impact of combined gaze and fearful expression cues in the process of attention orienting.

Neurocognitive mechanisms of gaze-expression interactions in face processing and social attention

The face conveys a rich source of non-verbal information used during social communication. While research has revealed how specific facial channels such as emotional expression are processed, little is known about the prioritization and integration of multiple cues in the face during dyadic exchanges. Classic models of face perception have emphasized the segregation of dynamic vs. static facial features along independent information processing pathways. Here we review recent behavioral and neuroscientific evidence suggesting that within the dynamic stream, concurrent changes in eye gaze and emotional expression can yield early independent effects on face judgments and covert shifts of visuospatial attention. These effects are partially segregated within initial visual afferent processing volleys, but are subsequently integrated in limbic regions such as the amygdala or via reentrant visual processing volleys. This spatiotemporal pattern may help to resolve otherwise perplexing discrepancies across behavioral studies of emotional influences on gaze-directed attentional cueing. Theoretical explanations of gaze-expression interactions are discussed, with special consideration of speed-of-processing (discriminability) and contextual (ambiguity) accounts. Future research in this area promises to reveal the mental chronometry of face processing and interpersonal attention, with implications for understanding how social referencing develops in infancy and is impaired in autism and other disorders of social cognition.

On the neural mechanisms subserving consciousness and attention

Consciousness, as described in the experimental literature, is a multi-faceted phenomenon, that impinges on other well-studied concepts such as attention and control. Do consciousness and attention refer to different aspects of the same core phenomenon, or do they correspond to distinct functions? One possibility to address this question is to examine the neural mechanisms underlying consciousness and attention. If consciousness and attention pertain to the same concept, they should rely on shared neural mechanisms. Conversely, if their underlying mechanisms are distinct, then consciousness and attention should be considered as distinct entities. This paper therefore reviews neurophysiological facts arguing in favor or against a tight relationship between consciousness and attention. Three neural mechanisms that have been associated with both attention and consciousness are examined (neural amplification, involvement of the fronto-parietal network, and oscillatory synchrony), to conclude that the commonalities between attention and consciousness at the neural level may have been overestimated. Last but not least, experiments in which both attention and consciousness were probed at the neural level point toward a dissociation between the two concepts. It therefore appears from this review that consciousness and attention rely on distinct neural properties, although they can interact at the behavioral level. It is proposed that a “cumulative influence model,” in which attention and consciousness correspond to distinct neural mechanisms feeding a single decisional process leading to behavior, fits best with available neural and behavioral data. In this view, consciousness should not be considered as a top-level executive function but should rather be defined by its experiential properties.

Reorienting of spatial attention in gaze cuing is reflected in N2pc

Research has shown that gaze cuing of attention is reflected in the modulation of P1 and N1 components of ERPs time-locked to target onset. Studies focusing on cue-locked analyses have produced mixed results. The present study examined ERP reflections of gaze cuing in further detail by recording electric brain activity from the scalp of participants engaged in a spatial cuing paradigm with noninformative gaze cues embedded in fearful, disgusted, or neutral faces. Unlike previous work, we focused on N2pc, a recent ERP index of attention shifting over space. Behavioral data showed that gaze-driven orienting was not influenced by facial expression. Importantly, electrophysiological data showed a significant amplitude modulation of the N2pc time-locked to target onset as a function of cue--target spatial congruence. This pattern, however, was independent of facial expression. The results are interpreted as evidence that N2pc can be used as a marker of reorienting of attention in spatially incongruent trials due to gaze cuing. The overall findings support the idea that the effects of facial expression on gaze cuing are weak and likely context-dependent.

Cortisol administration acutely reduces threat-selective spatial attention in healthy young men

There is mounting evidence that single administrations of glucocorticoids may acutely reduce human fear. We previously reported that administration of cortisol acutely reduced non-spatial selective attention to fearful faces and likewise reduced preferential processing of fearful faces in a spatial working memory task. Here we report the acute effects of 40 mg cortisol (administered in a double-blind, placebo-controlled crossover design) on a different experimental task for measuring threat-selective attention. Twenty healthy young males had to localize a target which was presented in a peripheral location that was either gazed at or not by a preceding dynamic happy or fearful face. This reliable method has been used repeatedly to demonstrate fear-driven selective attention. Present results showed that after placebo, as usual, the fearful gaze cues caused stronger orienting of attention than happy faces. Cortisol abolished this typical anxious response pattern, but only in low anxious participants. These data provide evidence that cortisol acutely influences also spatial threat-selective attention. Possible neuroendocrine mechanisms are discussed.

Neural bases of eye and gaze processing: the core of social cognition

Eyes and gaze are very important stimuli for human social interactions. Recent studies suggest that impairments in recognizing face identity, facial emotions or in inferring attention and intentions of others could be linked to difficulties in extracting the relevant information from the eye region including gaze direction. In this review, we address the central role of eyes and gaze in social cognition. We start with behavioral data demonstrating the importance of the eye region and the impact of gaze on the most significant aspects of face processing. We review neuropsychological cases and data from various imaging techniques such as fMRI/PET and ERP/MEG, in an attempt to best describe the spatio-temporal networks underlying these processes. The existence of a neuronal eye detector mechanism is discussed as well as the links between eye gaze and social cognition impairments in autism. We suggest impairments in processing eyes and gaze may represent a core deficiency in several other brain pathologies and may be central to abnormal social cognition.

Face and gaze processing in Prader-Willi syndrome

A number of developmental disorders of genetic origin show atypical aspects of face processing. However, little is known about face processing in Prader-Willi syndrome (PWS). PWS is of specific interest because it has two modes of inheritance (paternally derived deletion, DEL; maternal uniparental disomy, UPD) only one of which (UPD) is associated with an increased risk of autistic symptomology. We conducted electrophysiological (ERP) and behavioural measurements of face and eye-gaze processing in individuals with PWS derived from both modes of inheritance. Our hypothesis that UPD PWS would show a pattern of deficits resembling those seen in autism was only partially confirmed. Although some individuals from both groups showed deficits, as a whole the UPD group (N=8) and the DEL group (N=8) did not differ on behavioural measures of face processing or autistic symptoms. In contrast, the effect of face orientation and gaze direction on the amplitude of the N170 ERP component differed between the two PWS sub-types. Thus, while the behavioural tests did not discriminate between the UPD and deletion forms of the syndrome, electrophysiological measures of face processing did differentiate the groups.

Event-related potentials reveal temporal staging of dynamic facial expression and gaze shift effects on attentional orienting

Multiple sources of information from the face guide attention during social interaction. The present study modified the Posner cueing paradigm to investigate how dynamic changes in emotional expression and eye gaze in faces affect the neural processing of subsequent target stimuli. Event-related potentials (ERPs) were recorded while participants viewed centrally presented face displays in which gaze direction (left, direct, right) and facial expression (fearful, neutral) covaried in a fully crossed design. Gaze direction was not predictive of peripheral target location. ERP analysis revealed several sequential effects, including: (1) an early enhancement of target processing following fearful faces (P1); (2) an interaction between expression and gaze (N1), with enhanced target processing following fearful faces with rightward gaze; and (3) an interaction between gaze and target location (P3), with enhanced processing for invalidly cued left visual field targets. Behaviorally, participants responded faster to targets following fearful faces and targets presented in the right visual field, in concordance with the P1 and N1 effects, respectively. The findings indicate that two nonverbal social cues-facial expression and gaze direction-modulate attentional orienting across different temporal stages of processing. Results have implications for understanding the mental chronometry of shared attention and social referencing.

Is there a direct link between gaze perception and joint attention behaviours? Effects of gaze contrast polarity on oculomotor behaviour

Previous studies have found that attention is oriented in the direction of other people's gaze suggesting that gaze perception is related to the mechanisms of joint attention. However, the role of the perception of gaze direction on joint attention has been challenged. We investigated the effects of disrupting gaze perception on the orienting of observers' attention, in particular, whether orienting to gaze direction is affected by the disruptive effect of negative contrast polarity on gaze perception. A dynamic distracting gaze was presented to observers performing an endogenous saccadic task. Gaze perception was manipulated by reversing the contrast polarity between the sclera and the iris. With positive display polarity, eye movement recordings showed shorter saccadic latencies when the direction of the instructed saccade matched the direction of the distracting gaze, and a substantial number of erroneous saccades towards the direction of the perceived gaze when the latter did not match the instruction. Crucially, such effects were not found when gaze contrast polarity was reversed and gaze perception was impaired. These results extend previous studies by demonstrating the existence of a direct link between joint attention and the perception of gaze direction, and show how orienting of attention to other people's gaze can be suppressed.

Happy and fearful emotion in cues and targets modulate event-related potential indices of gaze-directed attentional orienting

The goal of the present study was to characterize the effects of valence in facial cues and object targets on event-related potential (ERPs) indices of gaze-directed orienting. Participants were shown faces at fixation that concurrently displayed dynamic gaze shifts and expression changes from neutral to fearful or happy emotions. Emotionally-salient target objects subsequently appeared in the periphery and were spatially congruent or incongruent with the gaze direction. ERPs were time-locked to target presentation. Three sequential ERP components were modulated by happy emotion, indicating a progression from an expression effect to a gaze-by-expression interaction to a target emotion effect. These effects included larger P1 amplitude over contralateral occipital sites for targets following happy faces, larger centrally distributed N1 amplitude for targets following happy faces with leftward gaze, and faster P3 latency for positive targets. In addition, parietally distributed P3 amplitude was reduced for validly cued targets following fearful expressions. Results are consistent with accounts of attentional broadening and motivational approach by happy emotion, and facilitation of spatially directed attention in the presence of fearful cues. The findings have implications for understanding how socioemotional signals in faces interact with each other and with emotional features of objects in the environment to alter attentional processes.

Electrocortical reflections of face and gaze processing in children with pervasive developmental disorder

BACKGROUND

Children with pervasive developmental disorder (PDD) show behavioral abnormalities in gaze and face processing, but recent studies have indicated that normal activation of face-specific brain areas in response to faces is possible in this group. It is not clear whether the brain activity related to gaze processing is also normal in children with PDD.

METHODS

Event-related brain potentials (ERPs) were measured during two spatial attention tasks in which a centrally presented stimulus served as cue for the location of a forthcoming target. In one task faces were used as cues, and in the other arrows. Seventeen children with PDD and 18 age- and IQ-matched control children were tested.

RESULTS

Face stimuli elicited the same specific ERP activity in both groups. Also, both children with PDD and controls showed shorter reaction times as well as larger amplitudes and shorter latency times of several ERP peaks to congruently cued targets than to incongruently cued targets in both tasks. However, children with PDD showed abnormally small occipital ERPs in response to both face and arrow stimuli.

CONCLUSIONS

The results provide evidence for the capability of normal processing of face and gaze change in children with PDD. The smaller occipital activity might be related to more general abnormalities in perception.