Your action does matter to me: Examining the role of the co-actor's action-effects in resolving the self-other discrimination problem.

Sharing a task with another person can introduce the need to discriminate representations that refer to our own action from that of the other person's. The current understanding is that information about the stimulus event drives the self-other discrimination process, as it promotes (via the reactivation of feature codes) the representation that encodes the corresponding action. However, this mechanistic explanation relies on experimental situations in which stimulus event information (e.g., spatial location) is always and directly available. Thus, it remains unclear whether and how we could successfully discriminate between self- and other related action representations in the absence of such information. The present study addressed this unanswered question using a novel joint Simon task-based paradigm. We report the results of three experiments in which we manipulated the availability of stimulus event information into the contralateral space. Our findings demonstrate that participants are able to compensate for the absence of stimulus event information by relying on temporal features of their co-actor's action-effects (Experiment 1). Even more surprising was that participants continued to monitor the temporal features of their co-actor's actions even when given a verbal signal by their co-actor (Experiments 2a), or full access to the common workspace (Experiment 2b). Our results are strong evidence that the representation of actions is not purely stimulus driven. They suggest that the temporal dimension of the other person's actions is able to drive the self-other discrimination process, in the same way as other perceptual dimensions and feature codes that are shared with the stimulus event.

Extraversion level predicts perceived benefits from social resources and tool use.

Social baseline theory states that there are differences in how humans integrate social resources into their economy of action when they face environmental demands. However, although several authors suggested that extraversion may be an indicator of the social baseline, no study has demonstrated it. The present study aims to test this hypothesis and, in particular, examines whether extraversion is a specific indicator of the social baseline. In two experiments, participants were asked to move rolls either alone (with their hands), or with the help of a social resource (Experiment 1), or a tool (Experiment 2). Results showed that extraversion predicted the choice to use both types of resource. Specifically, the more participants were extraverted, the more they tended to consider the use of the social resource or the tool as beneficial. We argue that these results indicate that extraversion is not specifically an indicator of the social baseline, but rather an indicator of how individuals integrate technical and social resources into their economy of action. In addition, this study encourages future research endeavors to define what constitutes a resource and how it could fit into the Social Baseline Theory.