dow without distracters, but this effect was negated when distracters were also presented. The performance of the persons with autism was the most impaired in the presence of distracters (Burack, 1994).The regarding factor was the tension between effective selective attention and distraction. The specific task used here was a forced-choice RT task adapted for use with persons with autism. All stimuli were in the form of simple geometric designs, as opposed to letters, to avoid confounding effects related to group differences in familiarity with letters. The conditions varied with regard to a) presence or absence of a spatial window highlighting the central area of the screen in which the target stimulus was presented, b) number of distracters and, c) proximity of the distracters to the target stimulus. Both the window and the distracters were presented simultaneously with the target stimulus. The location of the target stimuli was kept constant to eliminate the need to search for the target and to reduce the unpredictability of stimulus presentation that is thought to be associated with impaired attentional functioning and arousal modulation in persons with autism. With regard to number of distracters, more distracters would incur greater filtering costs and lead to greater interference with performance. Conversely, we expected that distracters farther from the target would interfere less with performance in that the cost of visual filtering would be minimized with distracters in the periphery of the attentional lens. All stimuli were presented on an IBM-XT computer with a color monitor, to which a keyboard with two response buttons was attached. In each trial, on of the target stimuli was presented in the center of the screen. The presence or absence of a window and the number and location of distracters varied by condition. In half of the trials, a window was imposed in the center section of the screen. In these trials, t...
