Cartoon of experimental conditions.

<p>In JUMP condition (left), after an unpredictable foreperiod of stable fixation (1200–1600 ms; eye position, white circles) on an initial fixation dot (green), a second dot (blue) appeared 10 deg to left of fixation. After 400 ms stimulus overlap, the fixation dot was turned off, serving as a signal to perform a saccadic eye movement to the second dot. Contingent on saccade onset, the target dot was switched off and reappeared 250 ms later with variable and unpredictable horizontal offset. Subjects performed a perceptual judgment on the apparent jump direction by means of a button press. In the VISUAL condition (middle), the trial started similar to JUMP condition, including the stimulus overlap, but with the exception of a second object (orange vertical bar) that appeared together with the target dot. Subjects kept initial fixation when the fixation cue disappeared and target and flanker object remained on screen for another 200 ms (mimicking saccadic reaction time). Then all cues disappeared for 50 ms (mimicking the visual transient induced by the saccade in JUMP and COMBI condition). Then, first the flanker and then the target reappeared (onset asynchrony, 200 ms, mimicking remaining BLANK duration after saccade in COMBI condition), with target position now coinciding with fixation and flanker position coinciding with previous relative position to target dot plus some variable and unpredictable offset. Here, subjects indicated the apparent relative displacement of the flanker object with respect to the target position. In COMBI condition (right), the task was identical to JUMP condition plus the flanker object of the VISUAL task. This flanker object remained on screen at same position throughout the trial.