Perceived depth vs. structural relevance in the object-superiority effect

Two experiments demonstrated letter-context effects that cannot easily be accounted for by postperceptual theories based on structural redundancy, figural goodness, or memory advantage. In Experiment 1, subjects identified the color of a letter fragment more accurately in letter than in nonletter contexts. In Experiment 2, subjects identified the feature presented in a precued color more accurately in letters than in nonlettcrs. We argue that these effects result from topdown perceptual processing.Briefly presented line segments are identified more accurately when they are embedded in coherent object-like contexts than when they are either embedded in noncoherent contexts or presented alone. These visual-context effects are referred to as the object-superiority effect (OSE) and the object-line effect (OLE), respectively. The original demonstrations of the OSE (Weisstein & Harris, 1974) and the OLE (Williams & Weisstein, 1978) were aimed at drawing an "analogy between object and word perception, and opening further opportunities for studying the effects of contexts on the perception of constituent elements without being restricted to linguistic material" (Williams & Weisstein, 1978, p. 85). Similarly, the welldocumented context effects in word perception inspired the exploration of a variety of visual-context effects with stimuli such as faces (e.g., Gyoba, Arimura, & Maruyama, 1980;Homa, Haver, & Schwartz, 1976;Purcell & Stewart, 1986van Santen & Jonides, 1978), letters (Schendel & Shaw, 1976), and real-world scenes (Biederman, 1972(Biederman, , 1981Biederman, Glass, & Stacey, 1973;Palmer, 1975). This research was supported by NSERC Grant A2579 to P. J. and NSERC Grant 001'0105451 to E. M. R. We are indebted to Liz Bosman, Phil Merikle, and Derek Besner for many constructive discussions of the issues, to Keith McGowan for writing the software, and to Susan Fraser for assisting in data collection. We would especially like to acknowledge Lester Krueger's helpful input during the process of revising earlier drafts of this paper. We also thank James Enns and two anonymous reviewers for their contributions. Correspondence should be addressed to either E. M. Reingold, Department of Psychology, University of Toronto, Erindale College, 3359 Mississauga Road, Mississauga, Ontario, Canada L5L lC6 (e-mail: reingold@psych.toronto.edu); after July 1993: School of Psychology, The University of New South Wales, P.O. Box I, Kensington, New South Wales, 2033, Australia; or P. Jolicoeur, Department of Psychology, University of Waterloo, Waterloo, Ontario, Canada N2L 3GI.Despite the intriguing surface similarities between the various visual-context effects, it may be premature to conclude that these effects are, in fact, comparable. For example, Weisstein and her colleagues (e.g., Weisstein & Harris, 1974;Williams & Weisstein, 1978) viewed the OSE and the OLE as analogous to the word-superiority effect (WSE) and the word-letter effect (WLE), respectively (for reviews of the WSE literature, see Baron, 1978;Johnston, 1981;Krueger, 1...

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Perceptual versus postperceptual mediation of visual context effects: Evidence from the letter-superiority effect

Reingold

Jolicœur

1993

“…A problem that soon becomes apparent in reviewing this literature is that none of the theories have been successful in specifying necessary conditions for the OLE. For example, a reliable OLE has been obtained with flat, two-dimensional stimuli (McClelland & Miller, 1979;Pomerantz et al, 1977), with disconnected lines of context (Earhard, 1980), with structurally irrelevant target lines (Lanze et al, 1982), without using a line mask (Williams & Weisstein, 1978;Klein, 1978), and with line detail at the point of fixation . Rather than searching further for specific stimulus properties, we will develop a more general theoretical account of the OLE.…”

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The role of redundancy in the object-line effect

Enns

Prinzmetal

1984

Subjects' identification of briefly presented target lines can sometimes be facilitated by including noninformative lines of context in the display (the object-lineeffect). Previous explanations for this effect have claimed that stimulus properties such as three-dimensionality, connectedness, structural relevance, line-masking, or fixation-point detail, allow line-in-context stimuli to be processed more efficiently than single-line stimuli. Instead of postulating special processing consequences for these stimulus properties, we propose two general preconditions for the object-line effect. Three experiments demonstrate that the effect occurs when lines-incontext have perceptual attributes that are correlated with the target lines and when the linesin-context are perceptually more dissimilar from one another than the single target lines.

“…Some authors . (e.g., McClelland & Miller, 1979) have suggested that aspects of their data are most readily accounted for by an "outside-in" processing strategy, and others (e.g., Lanze et al, 1982) cite unpublished data to support arguments favoring outside-in processing of geometric forms. At present, the strongest published evidence favoring such a processing disposition remains experimentation on unidimensional letter strings.…”

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“…For example, Prinzmetal and Banks (1977) have examined the degree to which Gestalt-like contexts can impair or facilitate detection of constituent elements or components of a given form. Weisstein and her associates (e.g., Lanze, Weisstein, & Harris, 1982;Weisstein & Harris, 1974;Williams & Weisstein, 1978) have attempted to demonstrate that coherence, connectedness, and three-dimensionality serve to enhance discriminability of constituent line elements in outline forms. In a variant of this approach, Pomerantz, Sager, and Stoever (1977) and Treisman and Paterson (1984) have endeavored to demonstrate how constituent components of form can combine with one another to form highly discriminable emergent features.…”

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An “outside-in” processing strategy in the perception of form

Earhard

Walker

1985

The discriminability of line segments in a number of different geometric forms was examined. The procedure used was to have one of the lines within a given form drawn thinner than the other lines. The location of the thin line varied randomly within the form, and subjects were required to detect its location. Three observations were made. First, outer line elements were discriminated more accurately than inner line elements. Second, the outer-line advantage appeared to reflect an attentional strategy: By presenting inner and outer lines independently, and informing subjects in advance as to whether target lines would be in the inner or outer area of the form, the outer line advantage could be eliminated. Third, consonant with a global attentional strategy, and in opposition to any retinally tied, peripheral-to-central scanning process, an outer-line advantage was evident regardless of whether the fixation point was positioned within or outside the forms, or whether outer lines were more peripheral than inner lines.