Varieties of size-specific visual selection.
Compared time to evaluate stimuli of varying sizes. When Ss expect an upcoming stimulus to be a certain size, response time increases with the disparity between expected and actual size. There are, however, 2 size adjustment processes, and they reflect 2 types of visual selection. In the first, a shape-specific image representation is used to separate a visual object from a superimposed distractor. These representations require the type of slow size scaling demonstrated in imagery experiments. The second size scaling process is faster and not shape-specific. At any given time the visual system is set to process information at a particular scale, and that scale can be adjusted to match an object's size. Because both selection mechanisms depend on size, they probably occur at a relatively low, spatially organized processing level. These findings lead to a new explanation for results that had been taken as evidence for attentional selection at the level of object representations.
Cave
K R
KR
Department of Brain and Cognitive Sciences, Massachusetts Institute of Technology.
Kosslyn
S M
SM
D001288:Attention; D004193:Discrimination Learning; D006801:Humans; D007092:Imagination; D009949:Orientation; D010364:Pattern Recognition, Visual; D011930:Reaction Time; D012718:Set, Psychology; D012858:Size Perception