B.3.6.2.2. Stimuli

In each trial, we presented ten circles, regularly arranged on an imaginary circle centred at fixation (radius: 5,8° angle at the viewing distance of 40 cm; see Figure 9). Nine distractors were gaped laterally (left or right, randomly), whereas one target was defined as the only item gaped vertically (top or bottom). Items could be of four different colours: blue, brown-orange, red, or green. The target's colour could be cued by a word ("bleu", "orange", "rouge", "vert", French words indicating colours) or not cued ("neutre", for neutral). This corresponded to the relevance factor. One item (target or distractor) could also be made salient, either in size or colour dimension. To vary size-salience, the size of nine items was reduced in some trials (leaving the salient item identical in each salience condition). In the no-salience condition, all items had the same size (1.2° angle). To make the target salient, all the distractors were made slightly smaller (0.9° angle). The salient item could also be a distractor. To that end, one distractor was kept at normal size (1.2° angle), while the eight remaining distractors and the target were reduced in size (0.9° angle). Therefore, the target, a distractor, or no item could be made salient by size. For colour-salience, similar manipulations were used. To make the target salient, the target was in one of the four possible colours, while all the nine distractors were of one of the three remaining colours, randomly chosen. To make a distractor salient, one distractor was in one of the four possible colours, while all the eight remaining distractors and the target were of one of the three remaining colours. For the no-salience condition, the target was always of one colour while the distractors were of the three remaining colours. The heterogeneity of the distractors was maintained by alternating the colours (e.g. red, green, blue, red, green... for adjacent items clockwise).