Figure 1. A cartoon showing the figural comparison, match-to-sample task.

A trial commences with an inter-trial interval (2 sec) during which a white central fixation cross is shown on a black background. A centrally presented black polygon is presented for 200 ms followed again by white central fixation cross on a black background (2 sec). Subsequently two white squares are presented to the left and right of the crosshair. In one of the two squares a polygon is presented. The participant must indicate whether the laterally presented stimulus was the ‘same’ or a ‘different’ polygon to that presented previously.