The role of structural redundancy in the perception of visual targets

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This study is concerned with three questions about the role of attention in peripheral detection: (1) Is the increased detection rate for spatial locations with high probabilities of target occurrence assigned to them due to sensitivity or criterion effects? (2) Does the effect of spatial cuing (probabilistic priming) require different explanations for letter detection and detection of luminance increments (Shaw, 1984)? (3) Can attention be shared between two separate locations cued to be most likely (Posner, Snyder, & Davidson, 1980)? These questions were investigated in two experiments, both using a signal detection plus localization task (rating method). In Experiment 1 (symbol detection), single or double cues indicating one or two most likely locations (three or two least likely locations) were presented. Introducing the second cued location resulted in a marked sensitivity gain for this position, relative to uncued locations in the single-cue condition. Decision criteria were more liberal for cued and more conservative for uncued locations. In Experiment 2, a luminance increment (single target probe) and two symbol detection (target plus distractors) tasks were compared. For symbol detection, there was a marked priming effect; but for luminance detection, cued locations showed no advantage in sensitivity. However, all tasks showed differential criterion setting for cued and for uncued locations. These results suggest that letter detection is capacity limited, whereas luminance increment detection is not, and furthermore, that decision criteria are largely preset according to a priori target probabilities assigned to particular locations.How does the focusing and dividing of attention influence perception? Recent research on this question has been concerned with two effects: that of "display N," that is, the number of nontargets in the display, and that of "probabilistic priming," that is, the relative frequencies of target occurrence assignedto individuallocations. Experimentswith accuracy as the dependent measure and with high error rates have established that an increase in the number of nontargets, withoutan increase in the number of targets, reduces target detectability (e.g., Estes & Taylor, 1964), and that variations in the probabilitieswith whichthe target occurs at particularlocationsenhancetarget detectability for the more likely positions relative to the less likely locations (e.g., M. L. Shaw & P. Shaw, 1977).Equivalenteffects havebeen demonstratedin reaction time (RT) For the explanation of these effects, it seems useful to assume that there are at least two functional stages between stimulus and response: In the first, "coding," stage, which may consist of a number of substages, each stimulus is converted into an internal representation. In the second, "decision," stage, the internal representation is used to determine a response, for example, a "target present-absent" decision. According to signal detection theory (SDT; Green & Swets, 1966), the internal stimulus representation is characte...

Section: Discussionmentioning

confidence: 85%

Sensitivity and criterion effects in the spatial cuing of visual attention

Müller

Findlay

1987

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179

“…First, the segmentation of an object into its component parts is often far more complicated than the segmentation of a word into its constituent letters (see Pomerantz, 1981). Second, a somewhat related problem is that a method for quantifying the level of contextual constraint (i.e., structural redundancy) for a given component part of a familiar object is not readily available (see Kinchla, 1977). Thus, it seems that a successful evaluation of the relationship between visual-context effects and redundancy in object perception requires the development of new experimental paradigms.…”

Section: Redundancy and Context Effects In Object Perceptionmentioning

confidence: 99%

“…However, when studying visual-context effects with familiar everyday objects, an additional source for subjects' knowledge of structural redundancies, namely preexperimental knowledge, needs to be considered. As pointed out by Kinchla (1977), subjects may employ their knowledge ofa correlation between familiar visual images and their parts (i.e., structural redundancy) to infer, rather than actually "see," those parts when the objects are presented for a very brief duration. In fact, familiar everyday objects are highly redundant.…”

Section: Redundancy and Context Effects In Object Perceptionmentioning

confidence: 99%

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

Reingold

Jolicœur

1993

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...

“…As mentioned above, there is a high degree of redundancy among the structural levels of a scene (Kinchla, 1977;Navon, 1981;Palmer, 1975). Because of this high correlation, or nonorthogonality, the information acquired from one level can potentially be used to infer or predict information at another level.…”

Section: The Present Experimentsmentioning

confidence: 99%

“…For example, recognizing a stove allows one to predict a kitchen scene is present, and vice versa. (It was for this reason that Kinchla, 1977, developed orthogonal bilevel stimuli to investigate processing of stimulus structure.) To manipulate attention to structural levels effectively, it was necessary to remove or minimize the effects of the correlation between structurallevels at the critical parts of the scene (i.e., the location of the cued object, or the entire scene itself).…”

Section: The Present Experimentsmentioning

confidence: 99%

Information tradeoffs in complex stimulus structure: Local and global levels in naturalistic scenes

Venturino

Gagnon

1992

An information tradeoff is an increased processing or utilization of information from one stirnulus source at the expense of processing or utilization of information from a different source. An experiment was conducted to determine whether information tradeoffs occurred when subjects attended selectively to one of two different structural levels of naturalistic scenes. The subjects' attentional focus was directed to either the global or local structure of a scene (i.e., the scene or an object in the scene, respectively) either before or after presentation of a scene. They then had to use the information obtained from a lOO·msec exposure of the scene to choose between two forced-choice alternatives that described one of the levels. The nature of the alternatives was such that both alternatives adequately characterized one of the structural levels on the basis of physical and semantic relations within the scene. Results showed that the subjects were significantly slower and less accurate when their attentional focus and the forced-choice alternatives were at different levels of stimulus structure than when they were at the same level, providing evidence of an information tradeoff when different types of information from a scene were used. When processing information from a particular structural level, information from the other level either was less available or was not used efficiently. Furthermore, the information tradeoffs were more severe in the precue than in the postcue condition, indicating differences in the efficiency of the selectivity process. The results are interpreted with respect to the role of selective attention in processing complex stimuli such as naturalistic scenes.The notion of selectivity in attention necessarily implies an information loss, in which some aspects of the stimulus environment are selected, processed, and transmitted at the expense of other aspects (Haber & Hershenson, 1980; Kinchla, 1980). This selectivity is an inevitable consequence of the limits of the human information processing system and functions to allow extraction of a coherent, meaningful flow of information from the myriad of environmental signals and stimulation impinging on a perceiver (Broadbent, 1958;Kahneman, 1973). A notable effect of selectivity is an information tradeoff, in which