Abstract
How strongly does the attentional spotlight constrain identification? Does the effect vary with perceptual load? Strong hypotheses are that the spotlight enables identification within it while disabling identification outside of it, and that the effect increases with higher perceptual load as per perceptual load theory. The main spotlight effect measured here was that a large window would facilitate perceiving large or global letters (in hierarchical Navon stimuli) whereas a small window would facilitate small or local letters. However, we have found that large differences in spotlight-size have only modest influences on global or local identification. In the experiments, we use a new method for manipulating the attentional spotlight. On each trial, observers first track a rectangular frame that either broadened to become a big window or narrowed to become a small window. Then two hierarchical letters appeared for a brief duration, and observers reported the global and local identities. As in earlier experiments, large and small spotlights effected large and small letters about equally; there was only a very modest relation between spotlight size and identification at the two levels. However, the spotlight manipulation was valid because it caused large effects of left versus right side on the screen. The present experiments show that a manipulation that should increase attention effects — a manipulation of perceptual load — does little to increase the spotlight effect. We degraded the Navon letters, resulting in a large reduction in perceptibility (a sizable increase in perceptual load). Nevertheless, the spotlight effects remained very modest in size, indicating that there is little relation between spotlight size and identification of global or local letters.
Meeting abstract presented at VSS 2017