Francesca Ciardo

Joint Action: Mental Representations, Shared Information and General Mechanisms for Coordinating with Others

In joint action, multiple people coordinate their actions to perform a task together. This often requires precise temporal and spatial coordination. How do co-actors achieve this? How do they coordinate their actions toward a shared task goal? Here, we provide an overview of the mental representations involved in joint action, discuss how co-actors share sensorimotor information and what general mechanisms support coordination with others. By deliberately extending the review to aspects such as the cultural context in which a joint action takes place, we pay tribute to the complex and variable nature of this social phenomenon.

Face age modulates gaze following in young adults

Gaze-following behaviour is considered crucial for social interactions which are influenced by social similarity. We investigated whether the degree of similarity, as indicated by the perceived age of another person, can modulate gaze following. Participants of three different age-groups (18–25; 35–45; over 65) performed an eye movement (a saccade) towards an instructed target while ignoring the gaze-shift of distracters of different age-ranges (6–10; 18–25; 35–45; over 70). The results show that gaze following was modulated by the distracter face age only for young adults. Particularly, the over 70 year-old distracters exerted the least interference effect. The distracters of a similar age-range as the young adults (18–25; 35–45) had the most effect, indicating a blurred own-age bias (OAB) only for the young age group. These findings suggest that face age can modulate gaze following, but this modulation could be due to factors other than just OAB (e.g., familiarity).

Action-space coding in social contexts

In two behavioural experiments we tested whether performing a spatial task along with another agent changes space representation by rendering some reference frames more/less salient than others. To this end, we used a Simon task in which stimuli were presented in four horizontal locations thus allowing for spatial coding according to multiple frames of reference. In Experiment 1 participants performed a go/no-go Simon task along another agent, each being in charge of one response. In Experiment 2 they performed a two-choice Simon task along another agent, each being in charge of two responses. Results showed that when participants were in charge of only one response, stimulus position was coded only with reference to the centre of the screen hence suggesting that the co-actor’s response, or the position of the co-actor, was represented and used as a reference for spatial coding. Differently, when participants were in charge of two responses, no effect of the social context emerged and spatial coding relied on multiple frames of reference, similarly to when the Simon task is performed individually. These findings provide insights on the influence played by the interaction between the social context (i.e. the presence of others) and task features on individual performance.

Trial-by-trial modulations in the orienting of attention elicited by gaze and arrow cues:

Recent findings suggested that the orienting of attention towards gazed at locations (i.e., the gaze cueing effect) could result from the conflict emerging in incongruent trials between the spatial information conveyed by gaze direction and the target spatial position. In two experiments, we assessed this hypothesis by investigating whether this effect is influenced by the same trial-by-trial modulations that are reported in a spatial conflict task, i.e., the Simon task. In Experiment 1, we compared the trial-by-trial modulations emerging in the Simon task with those emerging in a gaze cueing task, while in Experiment 2, we compared gaze and arrows cues. Trial-by-trial modulations were evident in both tasks. In the Simon task, correspondence sequence affected both corresponding and noncorresponding responses, this resulting in a larger Simon effect when the preceding trial was corresponding and an absent effect when the preceding trial was noncorresponding. Differently, in the gaze cueing task, congruence sequence affected only congruent responses with faster responses when the preceding trial was congruent compared to when it was incongruent, resulting in a larger gaze cuing effect when the preceding trial was congruent. Same results were evident with nonpredictive arrow cues. These findings speak against a spatial conflict account.

The role of perspective in discriminating between social and non-social intentions from reach-to-grasp kinematics

Making correct inferences regarding social and individual intentions may be crucial for successful interactions, especially when we are required to discriminate between cooperative and competitive behaviors. The results of previous studies indicate that reach-to-grasp kinematic parameters may be used to infer the social or individual outcome of a movement. However, the majority of the studies investigated this ability by presenting reach-to-grasp movements from a third-person perspective only. The aim of the present study was to assess whether the ability to recognize the intent associated to a reach-to-grasp movement varies as a function of perspective by manipulating the perspective of observation (second- and third-perspective) within participants. To this end, we presented participants with video clips of models performing a reach-to-grasp movement with different intents. The video clips were recorded both from a lateral view (third-person perspective) and from a frontal view (second-person perspective). After viewing the clips, in two subsequent tasks participants were asked to distinguish between social and non-social intentions by observing the initial phase of the same action recorded from the two different views. Results showed that, when a fast-speed movement was presented from a lateral view, participants were able to predict its social intention. In contrast, when the same movement was observed from a frontal view, performance was impaired. These results indicate that the ability to detect social intentions from motor cues can be biased by the visual perspective of the observer, specifically for fast-speed movements.

Response Coordination Emerges in Cooperative but Not Competitive Joint Task

Effective social interactions rely on humans’ ability to attune to others within social contexts. Recently, it has been proposed that the emergence of shared representations, as indexed by the Joint Simon effect (JSE), might result from interpersonal coordination (Malone et al., 2014). The present study aimed at examining interpersonal coordination in cooperative and competitive joint tasks. To this end, in two experiments we investigated response coordination, as reflected in instantaneous cross-correlation, when co-agents cooperate (Experiment 1) or compete against each other (Experiment 2). In both experiments, participants performed a go/no-go Simon task alone and together with another agent in two consecutive sessions. In line with previous studies, we found that social presence differently affected the JSE under cooperative and competitive instructions. Similarly, cooperation and competition were reflected in co-agents response coordination. For the cooperative session (Experiment 1), results showed higher percentage of interpersonal coordination for the joint condition, relative to when participants performed the task alone. No difference in the coordination of responses occurred between the individual and the joint conditions when co-agents were in competition (Experiment 2). Finally, results showed that interpersonal coordination between co-agents implies the emergence of the JSE. Taken together, our results suggest that shared representations seem to be a necessary, but not sufficient, condition for interpersonal coordination.