Experimental procedure.

<p>The visual target stimulus, 45° clockwise or counterclockwise (here clockwise) could be presented in the first or second interval. In this figure, the stimulus is shown in the first interval at suprathreshold contrast. After the green fixation cross disappeared, participants started to explore the haptic grating with the index finger of their dominant hand. Two intervals were presented on the screen, separated by a blank screen for 40 ms. After the second interval disappeared, subjects had to indicate in which interval the visual grating was presented. The grating's orientation alternated randomly between +/−45°. After the response a red fixation-cross appeared, indicating that the participant was not allowed to touch the grating. The motor made two random turns before the next trial started.