Modulation of the action control system by social intention: Unexpected social requests override preplanned action.

TLDR

Theories propose that social context influences the control of action. The study examined how an unexpected social request alters the kinematics of a preplanned action. Participants performed a grasp‑and‑place task while 20 % of trials included an unexpected human request; subsequent experiments varied the agent type, gesture, and gaze to isolate social factors. Kinematic changes occurred only when a human made a social request, but not when the perturbation involved a robot or a nonsocial human gesture.

Abstract

Four experiments investigated the influence of a sudden social request on the kinematics of a preplanned action. In Experiment 1, participants were requested to grasp an object and then locate it within a container (unperturbed trials). On 20% of trials, a human agent seated nearby the participant unexpectedly stretched out her arm and unfolded her hand as if to ask for the object (perturbed trials). In the remaining 3 experiments, similar procedures were adopted except that (a) the human was replaced by a robotic agent, (b) the gesture performed by the human agent did not imply a social request, and (c) the gaze of the human agent was not available. Only when the perturbation was characterized by a social request involving a human agent were there kinematic changes to the action directed toward the target. Conversely, no effects on kinematics were evident when the perturbation was caused by the robotic agent or by a human agent performing a nonsocial gesture. These findings are discussed in the light of current theories proposed to explain the effects of social context on the control of action.