Searching through subsets: a test of the visual indexing hypothesis

Authors: Burkell, Jacquelyn A.¹; Pylyshyn, Zenon W.²

Source: Spatial Vision, Volume 11, Number 2, 1997 , pp. 225-258(34)

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Abstract:

This paper presents three experiments investigating the claim that the visual system utilizes a primitive indexing mechanism (sometimes called FINSTS; Pylyshyn, 1989) to make non-contiguous features directly accessible for further visual processing. This claim is investigated using a variant of the conjunction search task in which subjects search among a subset of the items in a conjunction search display for targets defined by a conjunction of colour and orientation. The members of the subset were identified by virtue of the late onset of the objects' place-holders. The cued subset was manipulated to include either homogenous distractors or mixed distractors. Observers were able to select a subset of three items from among fifteen for further processing (Experiment 1); furthermore, a reaction time advantage for homogenous subsets over mixed subsets was observed, indicating that more than one of the subset is selected for further specialized processing. The homogeneous subset advantage held for subsets of two to five items (Experiment 2), and the time required to process the cued subset did not increase with increased dispersion of the items (Experiment 3). These results support the basic claim of the indexing theory: the claim that multiple visual indexes are used in selecting objects for visual processing.

Document Type: Research article

DOI: http://dx.doi.org/10.1163/156856897X00203

Affiliations: 1: Faculty of Communications and Open Learning, University of Western Ontario, London, Canada 2: Department of Psychology, Rutgers University, New Brunswick, NJ 08903, USA

Publication date: 1997-01-01

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