Abstract

It has been suggested that the perceptual load induced by varying display set size is confounded with the dilution among nontarget stimuli. A flanker compatibility task was conducted to examine the nature of dilution. In Experiments 1 and 2, a target letter was presented at fixation with three or six task-irrelevant flanking letters surrounding it. Distractor interference was modulated by the number of the distracting letters in Experiment 1 and the ratio of the number of the distracting letters to the total number of the flanking letters in Experiment 2. When seven different letters were presented as a target, distracting letters, and neutral letters in Experiment 3, the number of the distracting letters modulated distractor interference. These findings are inconsistent with Tsal and Benoni’s (2010) idea that dilution is due to perceptual interference in the preattentive processing stage, as well as Lavie’s (1995) perceptual load theory. We argue that distractor interference is modulated by the probability of a distractor capturing focused attention.