Fig. 1.

Design of the experimental task. First line: the OBS task. Participants observed the right hand of an actor moving an object rightward. Four objects were used. The observed action could be performed with a gentle (A1) or rude (A2) vitality form, and the task required participants to pay attention to the action’s vitality form. In the control condition, the participant observed the same action performed in a jerky way (A3). Second line: the EXE task. Participants held a little box and moved it with a gentle (B1, blue color) or rude (B2, red color) vitality form toward the actor in front of them, as shown in the screen. A cue positioned in the center of the screen indicated when to start the action. During action execution, they saw only the chest of the actor, and the actor’s hand was outside their field of vision. In the control condition, participants performed the same action in a neutral way (B3). All stimuli in the OBS and EXE tasks were viewed via digital visors (VisuaSTIM) with a 500,000 px × 0.25 square inch resolution and horizontal eye field of 30°.