Abstract
The roles of peripheral (local) and central (global) processing limitations in visual search are still not well understood. In the present study, the number of displayed stimuli (set-size) and the distance between neighbouring stimuli were varied as independently as possible in order to measure the effect of both. Stimuli were presented briefly and observers had to indicate the presence or absence of the target stimulus. Percentage correct was used as a measure of performance. Symmetrically and asymmetrically bisected squares were used as stimuli. There were two experimental conditions: target differed from distractors either by presence/absence of a simple feature (1) or it differed by relative position of the same components only (2). The effect of distance between stimuli (lateral masking) was found to be similar in the both conditions. The effect of set-size (with lateral masking effect eliminated) was much larger for relative position stimuli. The results support the view that perception of relative position of stimulus components is limited mainly by the capacity of central processing.