909547.fig.001a
(a)
909547.fig.001b
(b)
Figure 1: (a) Stimulus configuration used in the experiments. The figure shows the condition with coherently moving dots. Each sub-windows was 6.0 × 10.3 deg. In the example dots present in the upper subwindow move rightward, whereas dots in the bottom sub-window move rightward (thick black arrows); however we used the opposite condition as well. Gaussian blobs were flashed 8.0 deg above and below the central fixation point. In the example, the Gaussian blobs have a horizontal offset of 26.4 arcmin with respect to the fixation point. The white line that crosses the central fixation point delimits the two sub-windows, but it was not present during the experiment. We used also a condition with no moving dots and a condition in which dots moved randomly. See text for more details. (b) A schematic representation of the stimulus temporal sequence. Observers were required to fixate the fixation point at the center of the screen and after 1 s coherently moving dots were presented. In the example, dots in the upper sub-windows moved always rightward, whereas dots in the bottom sub-window moved always leftward (thick black arrows). After 150 ms two Gaussian blobs were flashed for 50 ms. It should be noted that when blobs were flashed the dots still moved. Then, moving dots continue to move for 150 ms. Each trial had a duration of 350 ms, with Gaussian blobs flashed in the middle of the temporal window. After the stimulus presentation the program waited until subject’s response. The same stimulus temporal sequence was used for the conditions with no moving dots and randomly moving dots.