Sequence of visual stimuli.

<p><i>A</i>. A green cross was the alert signal that a new trial was going to start. <i>B</i>. 400 random disks different in size, colour, and position, appeared. <i>C</i>. a red cross was displayed at the starting position of the movement for 150 ms. <i>D</i>. The red cross was substituted by d1 and d2 appeared on the left of d1 at the same time. <i>E</i>. d1 disappeared when d2 started to move upwards (as in this figure) or downwards. The white numbers in each box indicate the duration of the associated stimuli. In <i>D</i> the duration varies with respect to the experimental condition. The dimensions of the stimuli in this figure do not respect the real dimensions.