Brain stimulation to left prefrontal cortex modulates attentional orienting to gaze cues.

In social interactions, we rely on non-verbal cues like gaze direction to understand the behaviour of others. How we react to these cues is determined by the degree to which we believe that they originate from an entity with a mind capable of having internal states and showing intentional behaviour, a process called mind perception. While prior work has established a set of neural regions linked to mind perception, research has just begun to examine how mind perception affects social-cognitive mechanisms like gaze processing on a neuronal level. In the current experiment, participants performed a social attention task (i.e. attentional orienting to gaze cues) with either a human or a robot agent (i.e. manipulation of mind perception) while transcranial direct current stimulation (tDCS) was applied to prefrontal and temporo-parietal brain areas. The results show that temporo-parietal stimulation did not modulate mechanisms of social attention, neither in response to the human nor in response to the robot agent, whereas prefrontal stimulation enhanced attentional orienting in response to human gaze cues and attenuated attentional orienting in response to robot gaze cues. The findings suggest that mind perception modulates low-level mechanisms of social cognition via prefrontal structures, and that a certain degree of mind perception is essential in order for prefrontal stimulation to affect mechanisms of social attention. This article is part of the theme issue 'From social brains to social robots: applying neurocognitive insights to human-robot interaction'.

Averted body postures facilitate orienting of the eyes.

It is well established that certain social cues, such as averted eye gaze, can automatically initiate the orienting of another's spatial attention. However, whether human posture can also reflexively cue spatial attention remains unclear. The present study directly investigated whether averted neutral postures reflexively cue the attention of observers in a normal population of college students. Similar to classic gaze-cuing paradigms, non-predictive averted posture stimuli were presented prior to the onset of a peripheral target stimulus at one of five SOAs (100ms-500ms). Participants were instructed to move their eyes to the target as fast as possible. Eye-tracking data revealed that participants were significantly faster in initiating saccades when the posture direction was congruent with the target stimulus. Since covert attention shifts precede overt shifts in an obligatory fashion, this suggests that directional postures reflexively orient the attention of others. In line with previous work on gaze-cueing, the congruency effect of posture cue was maximal at the 300ms SOA. These results support the notion that a variety of social cues are used by the human visual system in determining the "direction of attention" of others, and also suggest that human body postures are salient stimuli capable of automatically shifting an observer's attention.

Mortality salience reduces the discrimination between in-group and out-group interactions: A functional MRI investigation using multi-voxel pattern analysis.

As a fundamental concern of human beings, mortality salience impacts various human social behaviors including intergroup interactions; however, the underlying neural signature remains obscure. Here, we examined the neural signatures underlying the impact of mortality reminders on in-group bias in costly punishment combining a second-party punishment task with multivariate pattern analysis of fMRI data. After mortality salience (MS) priming or general negative affect priming, participants received offers from racial in-group and out-group proposers and decided how to punish proposers by reducing their payoffs. We revealed that MS priming attenuated in-group bias and dampened the discriminated activation patterns pertaining to group identities in regions previously implicated in costly punishment, including dorsomedial prefrontal cortex, temporo-parietal junction, anterior cingulate cortex, and dorsolateral prefrontal cortex. The group identity represented in multivariate patterns of activity of these regions predicted in-group bias for the control condition, i.e., the stronger discriminative representations of group identities in these regions; the larger was the in-group bias. Furthermore, the in-group bias was reliably decoded by distributed activation patterns in the punishment-related networks but only in the control condition and not in the MS condition. These findings elucidate the neural underpinnings of the effects of mortality reminders on intergroup interaction. Hum Brain Mapp 38:1281-1298, 2017. © 2016 Wiley Periodicals, Inc.

Watch out! Directional threat-related postures cue attention and the eyes.

Previous work indicates that threatening facial expressions with averted eye gaze can act as a signal of imminent danger, enhancing attentional orienting in the gazed-at direction. However, this threat-related gaze-cueing effect is only present in individuals reporting high levels of anxiety. The present study used eye tracking to investigate whether additional directional social cues, such as averted angry and fearful human body postures, not only cue attention, but also the eyes. The data show that although body direction did not predict target location, anxious individuals made faster eye movements when fearful or angry postures were facing towards (congruent condition) rather than away (incongruent condition) from peripheral targets. Our results provide evidence for attentional cueing in response to threat-related directional body postures in those with anxiety. This suggests that for such individuals, attention is guided by threatening social stimuli in ways that can influence and bias eye movement behaviour.

Evidence from the eyes: Threatening postures hold attention.

Efficient detection of threat provides obvious survival advantages and has resulted in a fast and accurate threat-detection system. Although beneficial under normal circumstances, this system may become hypersensitive and cause threat-processing abnormalities. Past research has shown that anxious individuals have difficulty disengaging attention from threatening faces, but it is unknown whether other forms of threatening social stimuli also influence attentional orienting. Much like faces, human body postures are salient social stimuli, because they are informative of one's emotional state and next likely action. Additionally, postures can convey such information in situations in which another's facial expression is not easily visible. Here we investigated whether there is a threat-specific effect for high-anxious individuals, by measuring the time that it takes the eyes to leave the attended stimulus, a task-irrelevant body posture. The results showed that relative to nonthreating postures, threat-related postures hold attention in anxious individuals, providing further evidence of an anxiety-related attentional bias for threatening information. This is the first study to demonstrate that attentional disengagement from threatening postures is affected by emotional valence in those reporting anxiety.