title: Divided attention limits perception of 3-D object shapes.
abstract: Can one perceive multiple object shapes at once? We tested two benchmark models of object shape perception under divided attention: an unlimited-capacity and a fixed-capacity model. Under unlimited-capacity models, shapes are analyzed independently and in parallel. Under fixed-capacity models, shapes are processed at a fixed rate (as in a serial model). To distinguish these models, we compared conditions in which observers were presented with simultaneous or sequential presentations of a fixed number of objects (The extended simultaneous-sequential method: Scharff, Palmer, & Moore, 2011a, 2011b). We used novel physical objects as stimuli, minimizing the role of semantic categorization in the task. Observers searched for a specific object among similar objects. We ensured that non-shape stimulus properties such as color and texture could not be used to complete the task. Unpredictable viewing angles were used to preclude image-matching strategies. The results rejected unlimited-capacity models for object shape perception and were consistent with the predictions of a fixed-capacity model. In contrast, a task that required observers to recognize 2-D shapes with predictable viewing angles yielded an unlimited capacity result. Further experiments ruled out alternative explanations for the capacity limit, leading us to conclude that there is a fixed-capacity limit on the ability to perceive 3-D object shapes.
authors: Department of Psychology, University of Washington, Seattle, WA, USA. scharff@uw.edu
authors: Alec
authors: A
authors: Scharff
authors: John
authors: J
authors: Palmer
authors: Cathleen M
authors: CM
authors: Moore
mesh_terms: D001288:Attention / Q000502:physiology*; D003116:Color; D003118:Color Perception / Q000502:physiology*; D005556:Form Perception / Q000502:physiology*; D006801:Humans; D008297:Male; D008960:Models, Psychological; D010364:Pattern Recognition, Visual / Q000502:physiology*
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