In the context of the Covid-19 pandemic, barrier gestures such as regular hand-washing, social distancing, and wearing a face mask are highly recommended. Critically, interpersonal distance (IPD) depends on the affective dimension of social interaction, which might be affected by the current Covid-19 context. In the present internet-based experimental study, we analyzed the preferred IPD of 457 French participants when facing human-like characters that were either wearing a face mask or displaying a neutral, happy or angry facial expression. Results showed that IPD was significantly reduced when characters were wearing a face mask, as they were perceived as more trustworthy compared to the other conditions. Importantly, IPD was even more reduced in participants infected with Covid-19 or living in low-risk areas, while it was not affected by the predicted health of the characters. These findings shed further light on the psychological factors that motivate IPD adjustments, in particular when facing a collective threat. They are also of crucial importance for policy makers as they reveal that despite the indisputable value of wearing a face mask in the current pandemic context, their use should be accompanied by an emphasis on social distancing to prevent detrimental health consequences.

In recent decades, the ability to represent others’ mental states (i.e., theory of mind) has gained particular attention in various disciplines ranging from ethology to cognitive neuroscience. Despite the exponentially growing interest, the functional architecture of social cognition is still unclear. In the present review, we argue that not only the vocabulary but also most of the classic measures for theory of mind lack specificity. We examined classic tests used to assess theory of mind and noted that the majority of them do not require the participant to represent another’s mental state or, sometimes, any mental state at all. Our review reveals that numerous classic tests measure lower-level processes that do not directly test for theory of mind. We propose that more attention should be paid to methods used in this field of social cognition to improve the understanding of underlying concepts.

Optimal control models of biological movements are used to account for those internal variables that constrain voluntary goal-directed actions. They, however, do not take into account external environmental constraints as those associated to social intention. We investigated here the effects of the social context on kinematic characteristics of sequential actions consisting in placing an object on an initial pad (preparatory action) before reaching and grasping as fast as possible the object to move it to another location (main action). Reach-to-grasp actions were performed either in an isolated condition or in the presence of a partner (audience effect), located in the near or far space (effect of shared reachable space), and who could intervene on the object in a systematic fashion (effect of social intention effect) or not (effect of social uncertainty). Results showed an absence of audience effect but nevertheless an influence of the social context both on the main and the preparatory actions. In particular, a “localized” effect of shared reachable space was observed on the main action, which was smoother when performed within the reachable space of the partner. Furthermore, a “global” effect of social uncertainty was observed on both actions with faster and jerkier movements. Finally, social intention affected the preparatory action with higher wrist displacements and slower movements when the object was placed for the partner rather than placed for self-use. Overall, these results demonstrate specific effects of action space, social uncertainty and social intention on the planning of reach-to-grasp actions, in particular on the preparatory action, which was performed with no specific execution constraint. These findings underline the importance of considering the social context in optimal models of action control for human–robot interactions, in particular when focusing on the implementation of motor parameters required to afford intuitive interactions.

Being able to discriminate between what originates from ourselves and what originates from others is critical for efficient interactions with our social environment. However, it remains an open question whether self-other distinction is a domain-general mechanism that is involved in various social-cognitive functions or whether specific 'self-other distinction mechanisms' exist for each of these functions. On the neural level, there is evidence that self-other distinction is related to a specific brain region at the border of the superior temporal and inferior parietal cortex, the temporoparietal junction (TPJ). Demonstrating that the TPJ plays a role in social processes that require self-other distinction would support the idea of a domain-general mechanism of self-other distinction. In the present paper, we review evidence coming from clinical observations, neuroimaging experiments and a meta-analysis indicating the involvement of the TPJ in various cognitive operations requiring self-other distinction. At the perceptual level, we discuss the human ability to identify one's own body and to distinguish it from others. At the action level, we review research on the human ability to experience agency and the control of imitative response tendencies. Finally, at the mental-state level, we discuss the ability to attribute mental states to others. Based on this integrative review, we suggest that the TPJ, and in particular its dorsal part, supports a domain general ability to enhance task-relevant representations when self-related and other-related representations are in conflict. Finally, this conception allows us to propose a unifying architecture for the emergence of numerous sociocognitive abilities.

Peripersonal space represents the area around the body where objects are coded in motor terms for the purpose of voluntary goal-directed actions. Previous studies have suggested that peripersonal space is also a safe space linked with our private area, influencing interpersonal space in social contexts. However, whether these two spaces rely on similar embodied processes remains an open issue. In the present study, participants observed a point-light walker (PLW) approaching them from different directions and passing near them at different distances from their right or left shoulder. While approaching, the PLW disappeared at a distance of 2 m and the task for the participants was to estimate if the interpersonal distance, at the time the PLW would have reached their level, was comfortable or not. Between two sessions of comfort judgments, the participants manipulated a 70 cm tool entailing an extension of peripersonal space, or a 10 cm tool entailing no extension of peripersonal space. The results revealed that the comfortable interpersonal distance was larger when the PLW crossed the mid-sagittal plane of the participants than when it approached them laterally, with a concomitant increase of response time. After participants manipulated the long tool, comfortable interpersonal distance increased, but predominantly when the PLW trajectory implied crossing the participants' mid-sagittal plane. This effect was not observed when participants manipulated the short tool. Two control tasks showed that using the long tool modified the reachability (control 1), but not the time to passage (control 2) estimates of PLW stimuli, suggesting that tool use extended peripersonal space without changing perceived visual distances. Overall, the data show that comfortable interpersonal distance is linked to the representation of peripersonal space. As a consequence, increasing peripersonal space through tool use has the immediate consequence that comfortable interpersonal distance from another person also increases, suggesting that interpersonal-comfort space and peripersonal-reaching space share a common motor nature.

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Spatiotemporal parameters of voluntary motor action may help optimize human social interactions. Yet it is unknown whether individuals performing a cooperative task spontaneously perceive subtly informative social cues emerging through voluntary actions. In the present study, an auditory cue was provided through headphones to an actor and a partner who faced each other. Depending on the pitch of the auditory cue, either the actor or the partner were required to grasp and move a wooden dowel under time constraints from a central to a lateral position. Before this main action, the actor performed a preparatory action under no time constraint, consisting in placing the wooden dowel on the central location when receiving either a neutral ("prêt"-ready) or an informative auditory cue relative to who will be asked to perform the main action (the actor: "moi"-me, or the partner: "lui"-him). Although the task focused on the main action, analysis of motor performances revealed that actors performed the preparatory action with longer reaction times and higher trajectories when informed that the partner would be performing the main action. In this same condition, partners executed the main actions with shorter reaction times and lower velocities, despite having received no previous informative cues. These results demonstrate that the mere observation of socially driven motor actions spontaneously influences the low-level kinematics of voluntary motor actions performed by the observer during a cooperative motor task. These findings indicate that social intention can be anticipated from the mere observation of action patterns.

Peripersonal space is a multisensory representation of the environment around the body in relation to the motor system, underlying the interactions with the physical and social world. Although changing body properties and social context have been shown to alter the functional processing of space, little is known about how changing the value of objects influences the representation of peripersonal space. In two experiments, we tested the effect of modifying the spatial distribution of reward-yielding targets on manual reaching actions and peripersonal space representation. Before and after performing a target-selection task consisting of manually selecting a set of targets on a touch-screen table, participants performed a two-alternative forced-choice reachability-judgment task. In the target-selection task, half of the targets were associated with a reward (change of colour from grey to green, providing 1 point), the other half being associated with no reward (change of colour from grey to red, providing no point). In Experiment 1, the target-selection task was performed individually with the aim of maximizing the point count, and the distribution of the reward-yielding targets was either 50%, 25% or 75% in the proximal and distal spaces. In Experiment 2, the target-selection task was performed in a social context involving cooperation between two participants to maximize the point count, and the distribution of the reward-yielding targets was 50% in the proximal and distal spaces. Results showed that changing the distribution of the reward-yielding targets or introducing the social context modified concurrently the amplitude of self-generated manual reaching actions and the representation of peripersonal space. Moreover, a decrease of the amplitude of manual reaching actions caused a reduction of peripersonal space when resulting from the distribution of reward-yielding targets, while this effect was not observed in a social interaction context. In that case, the decreased amplitude of manual reaching actions was accompanied by an increase of peripersonal space representation, which was not due to the mere presence of a confederate (control experiment). We conclude that reward-dependent modulation of objects values in the environment modifies the representation of peripersonal space, when resulting from either self-generated motor actions or observation of motor actions performed by a confederate.