Kyllingsbæk, S. 1 , Sy, J. L. 2 & Giesbrecht, B. 2
1 Department of Psychology, University of Copenhagen
2 Department of Psychology, University of California, Santa Barbara
The allocation of visual processing capacity is a key topic in studies and theories of visual attention. The Load Theory of Lavie (1995) has proposed that allocation happens in two stages where processing resources are first allocated to task-relevant stimuli and secondly remaining capacity ‘spills over’ to task-irrelevant distractors. In contrast, the Theory of Visual Attention (TVA) by Bundesen (1990) assumes that allocation happens in a single step where processing capacity is allocated to all stimuli, both task-relevant as well as task-irrelevant, in proportion to their relative attentional weight. Here we present data from two partial report experiments where we varied the number and discriminability of the task-irrelevant stimuli (Experiment 1) and perceptual load (Experiment 2). The TVA fitted the data of the two experiments well thus favoring the simple explanation with a single stage of capacity allocation. We also show that the effects of varying perceptual load can only be explained by a combined effect of allocation of processing capacity as well as limits in visual working memory. Finally, we link the results to processing capacity understood at the neural level based on the Neural Theory of Visual Attention by Bundesen, Habekost, & Kyllingsbæk (2005).