SHIFTING ATTENTION IN VISUAL SPACE - TESTS OF MOVING-SPOTLIGHT MODELSVERSUS AN ACTIVITY-DISTRIBUTION MODEL

Participants were induced to concentrate preparatory attention at a ce ntral location, to identify a letter there, to identify a 2nd letter t o the extreme left or right of a central horizontal range of 5 locatio ns, and then to identify a 3rd letter at 1 of the central 5 locations. Analog and discrete versions of the moving-spotlight model predict th at response times to the 3rd letter will be most rapid at the location of the 2nd letter, whereas an activity-distribution model predicts th at the most rapid responses to the 3rd letter will be at the central l ocation, where preparatory attention is strongest. The data from 3 exp eriments, taken together, are inconsistent with the moving-spotlight m odels and are consistent with the activity-distribution model.