Mapping reflexive shifts of attention in eye-centered and hand-centered coordinate systems

Are eyes special? Gaze, but not pointing gestures, elicits a reversed congruency effect in a spatial Stroop task

Gaze stimuli can shape attention in a peculiar way as compared to non-social stimuli. For instance, in a spatial Stroop task, gaze stimuli elicit a reversed congruency effect (i.e., faster responses on incongruent than on congruent trials) as compared to arrows, for which a standard congruency effect emerges. Here, we tested whether the reversed congruency effect observed for gaze can emerge for other social signals such as pointing gestures. Participants discriminated the direction (left or right) indicated by gaze and pointing finger stimuli that appeared leftwards or rightwards with respect to a central fixation spot. Arrows were also employed as control non-social stimuli. A reversed congruency effect emerged for the gaze, whereas a standard congruency effect emerged for both the pointing finger and the arrows. This suggests that the reversed congruency effect is specific to gaze stimuli and does not embrace all social signals conveying spatial information.

Foot cues can elicit covert orienting of attention

Humans tend to orient their attentional resources towards the same location indicated by spatial signals coming from the others, such as pointing fingers, head turns, or eye-gaze. Here, two experiments investigated whether an attentional orienting response can be elicited even by foot cues. Participants were asked to localize a peripheral target while a task-irrelevant picture of a naked human foot, oriented leftward or rightward, was presented on the centre of the screen. The foot appeared in a neutral posture (i.e., standing upright) or an action-oriented posture (i.e., walking/running). In Experiment 1, neutral and action-oriented feet were presented in two distinct blocks, while in Experiment 2 they were presented intermixed. The results showed that the action-oriented foot, but not the neutral one, elicited an orienting response, though this only emerged in Experiment 2. This work suggests that attentional shifts can be induced by action-oriented foot cues, as long as these stimuli are made contextually salient.

Focused attention: its key role in gaze and arrow cues for determining where attention is directed

Others' gaze direction and traffic arrow signal lights play significant roles in guiding observers' attention in daily life. Previous studies have shown that gaze and arrow cues can direct attention to the cued location. However, it is ambiguous where gaze and arrow cues guide attention: the cued location or a broader cued region. Therefore, the present study adopted a primary cue-target task and manipulated possible target locations to explore this issue. The results revealed that due to the different physical characteristics of non-predictive gaze and arrow cues, physically unfocused-pointing gaze cues guided attention to a broader cued region, whereas focused-pointing arrow cues guided attention to the exact cued location. Furthermore, gaze cues could also direct attention to the exact cued location when observers' attention was focused in a top-down manner (with highly predictive probability). These findings suggest that where gaze and arrow cues direct attention depends on whether observers' attention is focused by the cues, either in a bottom-up or top-down manner. Accordingly, a preliminary framework called the "Focused-Diffused Attentional Orienting Model" is proposed to explain how gaze and arrow cues direct humans' attention. The present study enhances our understanding of human attentional orienting systems from a behavioral perspective.

"Be careful what you do": How social threat influences social attention driven by reach-to-grasp movements

Social attention is the ability to share with social partners the attentional focus on an object and to orient attentional resources after observing others' behaviors. In the present work, we analyzed whether social threat may influence social attention during the observation of social agents' reach-to-grasp movements. In two experimental studies, we adopted a Posner-like paradigm: participants were required to classify neutral stimuli appearing in a congruent or incongruent position with the actor's movement. Membership (ingroup vs. outgroup) and contextual cues (neutral vs. threatening objects) were manipulated. The results showed a robust action-cueing effect: responses to stimuli in a congruent position with the actor's action were faster than responses to incongruent stimuli. Interestingly, we found a stronger effect for the threatening outgroup (i.e., Iraqi) than for the ingroup (i.e., Italian), especially in presence of menacing objects. No effects were found when observing the non-threatening outgroup (i.e., Japanese).

Neural Mechanisms Underlying Conscious and Unconscious Gaze-Triggered Attentional Orienting in Autism Spectrum Disorder

Impaired joint attention represents the core clinical feature of autism spectrum disorder (ASD). Behavioral studies have suggested that gaze-triggered attentional orienting is intact in response to supraliminally presented eyes but impaired in response to subliminally presented eyes in individuals with ASD. However, the neural mechanisms underlying conscious and unconscious gaze-triggered attentional orienting remain unclear. We investigated this issue in ASD and typically developing (TD) individuals using event-related functional magnetic resonance imaging. The participants viewed cue stimuli of averted or straight eye gaze direction presented either supraliminally or subliminally and then localized a target. Reaction times were shorter when eye-gaze cues were directionally valid compared with when they were neutral under the supraliminal condition in both groups; the same pattern was found in the TD group but not the ASD group under the subliminal condition. The temporo–parieto–frontal regions showed stronger activation in response to averted eyes than to straight eyes in both groups under the supraliminal condition. The left amygdala was more activated while viewing averted vs. straight eyes in the TD group than in the ASD group under the subliminal condition. These findings provide an explanation for the neural mechanisms underlying the impairment in unconscious but not conscious gaze-triggered attentional orienting in individuals with ASD and suggest possible neurological and behavioral interventions to facilitate their joint attention behaviors.

Fortunes and misfortunes of political leaders reflected in the eyes of their electors

Gaze-following is a pivotal social behaviour that, although largely automatic, is permeable to high-order variables like political affiliation. A few years ago we reported that the gaze of Italian right-wing voters was selectively captured by the gaze of their leader Silvio Berlusconi. This effect was particularly evident in voters who saw themselves as similar to Berlusconi. Two years later, we were able to run the present follow-up study because Berlusconi's popularity had drastically dropped due to sex and political scandals, and he resigned from office. In a representative subsample of our original group, we investigated whether perceived similarity and gaze-following reflected Berlusconi's loss in popularity. We were also able to test the same hypothesis in an independent group of right-wing voters when their leader, Renata Polverini, resigned as Governor of 'Regione Lazio' due to political scandals. Our results show that the leaders' fall in popularity paralleled the reduction of their gaze's attracting power, as well as the decrease in similarity perceived by their voters. The less similar right-wing voters felt to their leader, the less they followed his/her gaze. Thus, the present experimental findings suggest that gaze-following can be modulated by complex situational and dispositional factors such as leader's popularity and voter-leader perceived similarity.

Altered orienting of attention in anorexia nervosa

The study of cognitive processes in anorexia nervosa (AN) is largely unexplored, although recent evidence suggests the presence of impairments in both social cognition and attention processing. Here we investigated AN patients' ability to orient attention in response to social and symbolic visual stimuli. AN patients and matched controls performed a task in which gaze and pointing gestures acted as social directional cues for spatial attention. Arrows were also included as symbolic cue. On each trial, a centrally-placed cue appeared oriented rightwards or leftwards. After either 200 or 700ms, a lateralized neutral target (a letter) requiring a discrimination response appeared in a location either spatially congruent or incongruent with the directional cue. Controls showed a reliable orienting irrespective of both temporal interval and cue type. AN patients showed a reliable orienting at both temporal intervals only in response to pointing gestures. Both gaze and arrow cues failed to orient attention at the short temporal interval, that is when attention is under reflexive control, whereas a reliable orienting emerged at the long temporal interval. These results provide preliminary evidence of altered reflexive orienting of attention in AN patients that does not extend to body-related cues such as pointing gestures.

Neural mechanisms underlying conscious and unconscious attentional shifts triggered by eye gaze

Behavioral studies have shown that eye gaze triggers attentional shifts both with and without conscious awareness. However, the neural substrates of conscious and unconscious attentional shifts triggered by eye gaze remain unclear. To investigate this issue, we measured brain activity using event-related functional magnetic resonance imaging while participants observed averted or straight eye-gaze cues presented supraliminally or subliminally in the central visual field and then localized a subsequent target in the peripheral visual field. Reaction times for localizing the targets were shorter under both supraliminal and subliminal conditions when eye-gaze cues were directionally congruent with the target locations than when they were directionally neutral. Conjunction analyses revealed that a bilateral cortical network, including the middle temporal gyri, inferior parietal lobules, anterior cingulate cortices, and superior and middle frontal gyri, was activated more in response to averted eyes than to straight eyes under both supraliminal and subliminal conditions. Interaction analyses revealed that the right inferior parietal lobule was specifically active when participants viewed averted eyes relative to straight eyes under the supraliminal condition; the bilateral subcortical regions, including the superior colliculus and amygdala, and the middle temporal and inferior frontal gyri in the right hemisphere were activated in response to averted versus straight eyes under the subliminal condition. These results suggest commonalities and differences in the neural mechanisms underlying conscious and unconscious attentional shifts triggered by eye gaze.

The attracting power of the gaze of politicians is modulated by the personality and ideological attitude of their voters: a functional magnetic resonance imaging study

Observing someone rapidly moving their eyes induces reflexive shifts of overt and covert attention in the onlooker. Previous studies have shown that this process can be modulated by the onlooker's personality, as well as by the social features of the person depicted in the cued face. Here, we investigated whether an individual's preference for social dominance orientation, in-group perceived similarity (PS), and political affiliation of the cued-face modulated neural activity within specific nodes of the social attention network. During functional magnetic resonance imaging, participants were requested to perform a gaze-following task to investigate whether the directional gaze of various Italian political personages might influence the oculomotor behaviour of in-group or out-group voters. After scanning, we acquired measures of PS in personality traits with each political personage and preference for social dominance orientation. Behavioural data showed that higher gaze interference for in-group than out-group political personages was predicted by a higher preference for social hierarchy. Higher blood oxygenation level-dependent activity in incongruent vs. congruent conditions was found in areas associated with orienting to socially salient events and monitoring response conflict, namely the left frontal eye field, right supramarginal gyrus, mid-cingulate cortex and left anterior insula. Interestingly, higher ratings of PS with the in-group and less preference for social hierarchy predicted increased activity in the left frontal eye field during distracting gaze movements of in-group as compared with out-group political personages. Our results suggest that neural activity in the social orienting circuit is modulated by higher-order social dimensions, such as in-group PS and individual differences in ideological attitudes.

The politics of attention contextualized: gaze but not arrow cuing of attention is moderated by political temperament

It is known that an averted gaze can trigger shifts of attention in an observer, a phenomenon known as gaze-cuing effect. Recently, Dodd et al. (Atten Percept Psychophys 73:24-29, 2011) have reported a reliable gaze-cuing effect for liberals but not for conservatives. The present study tested whether this result is gaze-specific or extends over nonsocial spatial signals. Conservatives and liberals took part in a spatial-cuing task in which centrally placed gaze and arrow cues, pointing rightward or leftward, were followed by a peripheral onset target requiring a simple detection response. Whereas a reliable cuing effect was present for both gaze and arrow cues in the case of liberals, conservatives showed a reduced cuing response only for gaze cues. These results provide further support for the pattern reported by Dodd et al. (2011) and are consistent with the view that conservatives are less susceptible to the influence of spatial cues provided by other individuals.

The role of the oculomotor system in covert social attention

Observing a change in gaze direction triggers a reflexive shift of attention and appears to engage the eye-movement system. However, the functional relationship between social attention and this oculomotor activation is unclear. One extremely influential hypothesis is that the preparation of a saccadic eye movement is necessary and sufficient for a covert, reflexive shift of attention (the premotor theory of attention; Rizzolatti et al., 1994). Surprisingly, this theory has not been directly tested with respect to reflexive gaze cueing. In order to address this issue, gaze cueing, peripheral cueing, and arrow cueing were examined under conditions in which some stimuli appeared at locations that could not become the goal of a saccadic eye movement. It was observed that peripheral cues failed to elicit reflexive attentional orienting when targets appeared beyond the range of eye movements. Similarly, nonpredictive arrow cues were ineffective when targets could not become the goal of a saccade. In contrast, significant gaze-cueing effects were still observed when targets were beyond the range of eye movements. These data demonstrate that the mechanisms involved in gaze cueing are dissociated from those involved in exogenous orienting to peripheral or arrow cues. Furthermore, the findings suggest that, unlike peripheral cueing and reflexive arrow cueing, gaze cueing is independent of oculomotor control. We conclude that the premotor theory does not offer a compelling explanation for gaze cueing.

Interpersonal multisensory stimulation reduces the overwhelming distracting power of self-gaze: psychophysical evidence for 'engazement'

One's own face and gaze are never seen directly but only in a mirror. Yet, these stimuli capture attention more powerfully than others' face and gaze, suggesting the self is special for brain and behavior. Synchronous touches felt on one's own and seen on the face of others induce the sensation of including others in one's own face (enfacement). We demonstrate that enfacement may also reduce the overwhelming distracting power of self-gaze. This effect, hereafter called ‘engazement', depends on the perceived physical attractiveness and inner beauty of the pair partner. Thus, we highlight for the first time the close link between enfacement and engazement by showing that changes of the self-face representation induced by facial visuo-tactile stimulation extend to gaze following, a separate process likely underpinned by different neural substrates. Moreover, although gaze following is a largely automatic, engazement is penetrable to the influence of social variables, such as positive interpersonal perception.

rTMS-induced virtual lesion of the posterior parietal cortex (PPC) alters the control of reflexive shifts of social attention triggered by pointing hands

In highly social groups like human and non-human primates, gaze and pointing cues are fundamentally important for directing the attention of conspecifics. Although neuroimaging studies indicate that shifts of attention triggered by observation of social cues activate the onlookers׳ fronto-parietal cortices, information on whether these regions play a causative role in orienting and re-orienting of social attention is lacking. To advance our understanding of this, we used event-related repetitive dual pulse transcranial magnetic stimulation to interfere with neural activity in the right frontal eye field (rFEF) and posterior parietal cortex (rPPC). This procedure allowed us to explore how inhibiting rFEF and rPPC influences shifts of attention triggered by the observation of body-related (gaze and hand) and non body-related (arrow) directional distractors. Participants were asked to perform a leftward or rightward pointing movement according to the color change of a central imperative signal while ignoring a distractor, which was either a gaze, a pointing hand or an arrow. Stimulation of rPPC in a region supposedly linked to attentional re-orienting and to planning and execution of upper limb movements increased the reflexive tendency to follow distracting pointing hands but not oriented gaze or arrows. These findings suggest that inhibition of cortical structures that control attentional shifts triggered by social stimuli brings forth an increase of the cost of attentional re-orienting. Moreover, our results provide the first causative evidence that reflexive social attention in humans may be coded according to body-part-centered frames of reference.

A look into the ballot box: gaze following conveys information about implicit attitudes toward politicians

Although considered a predominantly automatic social behaviour, gaze following (GF) is sensitive to complex social factors like political affiliation and ideology. The present study aimed to determine whether the differential proneness to in-group leaders' gaze is related to attitudes towards politicians as measured by other implicit procedures. A GF paradigm was used to test the extent to which electors were prone to gaze following when attending to two female candidates who competed for the position of governor in an Italian election campaign. Results showed that GF significantly predicts voting intentions. Also, it was found that GF is significantly and positively correlated with the Implicit Association Test (IAT). Hierarchical multiple regression models illustrated that GF and IAT uniquely predict voting intentions, accounting for a substantial proportion of variance. Thus GF and IAT, even though significantly related, seem to account for different aspects of the attitudes towards candidates. A multivariate regression model showed that, while IAT scores are predicted by explicit emotions toward the candidate, GF is predicted by the candidates' perceived influence within their political coalition.

Follow my eyes: the gaze of politicians reflexively captures the gaze of ingroup voters

Studies in human and non-human primates indicate that basic socio-cognitive operations are inherently linked to the power of gaze in capturing reflexively the attention of an observer. Although monkey studies indicate that the automatic tendency to follow the gaze of a conspecific is modulated by the leader-follower social status, evidence for such effects in humans is meager. Here, we used a gaze following paradigm where the directional gaze of right- or left-wing Italian political characters could influence the oculomotor behavior of ingroup or outgroup voters. We show that the gaze of Berlusconi, the right-wing leader currently dominating the Italian political landscape, potentiates and inhibits gaze following behavior in ingroup and outgroup voters, respectively. Importantly, the higher the perceived similarity in personality traits between voters and Berlusconi, the stronger the gaze interference effect. Thus, higher-order social variables such as political leadership and affiliation prepotently affect reflexive shifts of attention.