Experimental setup.

<p>(A) The digital game. The participants controlled a paddle to hit an approaching ball. The display has a 3D feel, so the more distant computer’s paddle is smaller and further away. In the first run they controlled the paddle using an fMRI-compatible eye tracking system; in the second run, the paddle was controlled by moving one LED that slid over a custom support (B). (C) Schematic representation of a run. The lower row shows the duration of the task or stimulus represented in the upper row. Each run consisted of 6 observation blocks (OBS BLOCK; represented in blue) and 6 execution blocks (PLAY BLOCK; represented in green). Execution and observation blocks were preceded by a fixation task where participants stared at a grey cross in the middle of a black screen for 19s (fixation condition; represented by the + sign). After each fixation task, an advisory word (“play” or “watch”) appeared for 1s to inform the subject about the next phase.