Figure 1.

Example “distractor present” letter search stimulus displays in (A) low perceptual load and (B) high perceptual load. All stimuli were presented on a black background, with all letter stimuli presented in light gray. The letter circle radius subtended 1.6° degrees of visual angle, with the target letters subtending 0.6° by 0.4°. In the low load condition (A), nontarget positions were occupied by small ‘o’s (0.15° by 0.12°). In the high load condition (B) the five nontarget positions were occupied by heterogeneous angular letters of the same dimensions as the target-randomly chosen from the set K, V, W, Z, M, and H. On distractor-present trials (10% trials), a full-color cartoon image (subtending 2.8–4° vertically by 2.8–3.2° horizontally) was presented 4.6° from fixation with a minimum of 0.6° edge to edge from nearest letter stimulus. Each distractor image was drawn with equal probability from the following set of cartoon characters: Superman, Spiderman, Spongebob Squarepants, Pikachu, Mickey Mouse, and Donald Duck.