Academic journal article Attention, Perception and Psychophysics

Part-Whole Information Assists in Topological × Topological but Not in Orientation × Orientation Conjunction Searches

Academic journal article Attention, Perception and Psychophysics

Part-Whole Information Assists in Topological × Topological but Not in Orientation × Orientation Conjunction Searches

Article excerpt

Published online: 23 January 2015

© The Psychonomic Society, Inc. 2015

Abstract Visual search is a routine task used in everyday life and is an important field of research in cognitive psychology. In laboratory settings, it has been shown that search for a target defined by a unique conjunction of two colours is more efficient if one colour surrounds the other (a part-whole search) compared to when no such hierarchical structural relationship exists (a part-part search; Wolfe et al. in Perception & Psychophysics, 55,537,1994). A similar result has been shown to hold for size × size conjunction searches (Bilsky & Wolfe in Perception & Psychophysics, 57,749, 1995). We show that this result also holds for topology × topology conjunction searches (where the stimuli are either hollow or filled), but not for orientation × orientation conjunction searches. We use the simultaneous-sequential paradigm to investigate a possible reason for the inefficiency of part-whole orientation search compared with the efficiency of part-whole searches of other features. We argue that two different attribute values from the same dimension can be processed independently, without interfering with each other for colour, size, and topology, but not for orientation. Because it is obviously more efficient to process a conjunction stimulus when both components of the conjunction can be processed without mutual interference, it follows that colour × colour, size × size, and topological × topology part-whole conjunction searches are likely to be more efficient than orientation × orientation part-whole conjunction searches.

Keywords Visual search . Attention: selective . Attention: interactions with memory

In everyday and professional life, we often need to perform visual search tasks, such as looking for a friend at a train station, or spotting tumours on an x-ray. In a typical laboratory visual search task, an observer looks for a designated target item among a variable number of distractor items. Performance often is quantified as the average time taken to locate the target as a function of the number of distractor items (i.e., the set size; Treisman & Gelade, 1980). The reciprocal of this measure is known as the search efficiency (Wolfe, 1998). Search efficiency reflects how well attention can be guided towards the target (Chun & Wolfe, 1996; Wolfe, FriedmanHill, & Bilsky, 1994). When a target differs from the distractors on a single attribute (e.g., colour, size, orientation, etc.), search is generally fast (Treisman & Gelade, 1980; Wolfe, 2007; Wolfe, Cave, & Franzel, 1989). Such searches often are termed feature searches as attention can be directed to the target based on its unique feature. Alternatively, the target and distractors may share the same attributes and only differ in the way that the attributes are combined. These searches are usually referred to as conjunction searches.

In some situations even conjunction searches can be quite efficient. Typically, this occurs when the attributes are derived from different dimensions, for example a colour × orientation conjunction search, such as searching for a red vertical target rectangle among distractors, half of which are green and vertical rectangles, and the remainder of which are red and horizontal rectangles (Treisman & Sato, 1990; Wolfe et al., 1989;Wolfe et al., 1990; Wolfe, Yee, & Friedman-Hill, 1992). Conversely, where attributes of a conjunctive search are derived from the same attribute dimension, search is generally inefficient (e.g. Wolfe et al., 1990). However, there is a notable exception to this rule. Within-dimension conjunction searches may be efficient if the attributes exhibit a structural hierarchy (Bilsky & Wolfe, 1995;Wolfeetal., 1994). We use the term "hierarchy" in the same restricted sense as it was used in these previous studies: to refer to the case when the outer region of an object differs from its inner region. …

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