Bradley S. Gibson

Stimulus-Driven Attentional Capture Is Contingent on Attentional Set for Displaywide Visual Features

This research showed that the current criterion for stimulus-driven attentional capture is not sufficient to rule out goal-directed processes that are critical for producing attentional capture. This was shown by demonstrating a contingency between displaywide visual features (i.e., features that signal the appearance of the task-relevant target display as a whole) and the features that capture attention. In Experiment 1, the target display was signaled by both color and onset; in Experiment 2, the target display was signaled only by onset. As expected, Experiment 1 showed that task-irrelevant color and onset distractors both captured attention, whereas Experiment 2 showed that only onset distractors captured attention. These contingencies suggest that the strongest evidence currently available for stimulus-driven attentional capture may be caused by goal-directed processes.

Must Figure-Ground Organization Precede Object Recognition? An Assumption in Peril

The assumption that figure-ground segmentation must precede object or shape recognition has been central to theories of visual perception We showed that assumption to be incorrect in an experiment in which observers reported the first perceived figure-ground organization of briefly exposed stimuli depicting two regions sharing a figure-ground border We manipulated the symmetry of the two regions and their orientation-dependent denotivity (roughly, their meaningfulness), and measured how each of these variables influenced figure-ground reports when the stimuli were exposed for 14, 28, 57, 86, or 100 ms, and followed immediately by a mask Influences on figure-ground organization from both symmetry and orientation-dependent object recognition processes were found, both were observed first in the 28-ms condition Object recognition inputs did not dominate symmetry inputs We suggest that object recognition processes may operate simultaneously on both sides of edges detected before figure-ground relationships are determined

Inhibition of return to object-based and environment-based locations

Inhibition of return (IOR) has been described in terms of two functional components. The locationbased component is associated with descriptions of spatially fixed, environmental locations; the object-based component is associated with more abstract descriptions of spatially invariant objects. In the present study, we hypothesized that the location-based component may also be associated with descriptions of spatially invariant objects because, like environment-based descriptions, object-based descriptions have an intrinsic spatial structure. To test this hypothesis, we employed a computer-generated depiction of a brick that rotated in depth between the presentations of cue and target. The results of four experiments showed that IOR accrued to locations that remained fixed with respect to the brick as well as the environment, suggesting that both object-based and environment-based descriptions can influence location-based IOR.

Object recognition contributions to figure-ground organization: Operations on outlines and subjective contours

In previous research, replicated here, we found that some object recognition processes influence figure-ground organization. We have proposed that these object recognition processes operate on edges (or contours)detected early in visual processing, rather than on regions. Consistent with this proposal, influences from object recognition on figure-ground organization were previously observed in both pictures and stereograms depicting regions of different luminance, but not in randomdot stereograms, where edges arise late in processing (Peterson & Gibson, 1993). In the present experiments, we examined whether or not two other types of contours—outlines and subjective contours—enable object recognition influences on figure-ground organization. For both types of contours we observed a pattern of effects similar to that originally obtained with luminance edges. The results of these experiments are valuable for distinguishing between alternative views of the mechanisms mediating object recognition influences on figure-ground organization. In addition, in both Experiments 1 and 2, fixated regions were seen as figure longer than nonfixated regions, suggesting that fixation location must be included among the variables relevant to figure-ground organization.

Surprise! An Unexpected Color Singleton Does Not Capture Attention in Visual Search

The existence of a pure form of stimulus-driven attentional control has been aligned exclusively with the existence of attentional capture. Unfortunately, there has been little evidence provided in support of attentional capture. The present study investigated whether the repeated failure to observe attentional capture might be due to the way in which attentional capture has been measured. A new visual search procedure was used to investigate whether attention would be captured by an initial and unexpected encounter with a color singleton. Despite this important change in procedure, the color singleton still did not capture attention. Further evidence showed that visual search for the color singleton could be highly efficient, but only after its relevance became established, and that the failure to observe capture in the present experiment was not due to other potentially detrimental effects of surprise. The present results suggest that new conceptions of stimulus-driven attentional control are required.

Object continuity in apparent motion and attention.

Recent theories of attention have emphasized the role of object-based representations in visual selection. One defining property of any object is spatiotemporal continuity. The present experiments show that the continuity property may underlie two seemingly unrelated perceptual phenomena: attentional capture by abrupt visual onset and the appearance of bistable apparent motion displays. In Experiment 1, observers carried out two visual tasks. In the first task, they reported the appearance of a bistable apparent-motion (or Ternus) display. Whether group or element motion was perceived depended on the duration of the blank interval between successive frames. In the second task, subjects engaged in visual search for a prespecified target, and one each trial one element was briefly flickered off and back on. The degree to which that element captured attention also depended on the duration of the temporal gap. The time course of the gap duration effect in the visual search task was very similar to that for the Ternus display. In Experiment 2, we ruled out the possibility that the presence of an abrupt offset caused the results of Experiment 1. It is argued that the apparent motion and attentional capture phenomena examined here may reflect the operation of the same underlying mechanism: in both cases, a sufficiently long temporal gap disrupts spatiotemporal continuity, thereby fundamentally changing the perceived organization of the display.

Visual Attention and the Semantics of Space Beyond Central and Peripheral Cues

The distinction between central and peripheral cues has played an important role in understanding the functional nature of visual attention for the past 30 years. In the present article, we propose a new taxonomy that is based on linguistic categories of spatial relations. Within this framework, spatial cues are categorized as either “projective” or “deictic.” Using an empirical diagnostic, we demonstrate that the word cues above, below, left, and right express projective spatial relations, whereas arrow cues, eye-gaze cues, and abrupt-onset cues express deictic spatial relations. Thus, the projective-versus-deictic distinction crosscuts the more traditional central-versus-peripheral distinction. The theoretical utility of this new distinction is discussed in the context of recent evidence suggesting that a variety of central cues can elicit reflexive orienting.

Inhibition of return and attentional control settings

In the present study, we used a spatial cuing paradigm in conjunction with a choice identification task to investigate whether exogenous attentional orienting and inhibition of return are affected by attentional control settings. As in previous studies (e.g., Folk, Remington, & Johnston, 1992), onset- and color-defined targets were crossed with uninformative onset-and color-defined cues. As expected, when the cue-target stimulus onset asynchrony (SOA) was short (i.e., 100 msec), the results showed that exogenous attentional orienting was contingent on attentional set; attentional capture occurred in response to a particular cue only when the feature that defined the cue also defined the target (Folk et al., 1992). More importantly, when the cue-target SOA was long (i.e., 1,000 msec), the results showed that the occurrence of inhibition of return was also contingent on attentional set, at least partially so; inhibition of return occurred in response to onset cues only when they preceded onset targets. In contrast, inhibition of return never occurred in response to color cues (at a variety of long SO As). The associations and dissociations that were observed between exogenous attentional orienting and inhibition of return are discussed in terms of posterior and anterior attention networks in the brain (Posner & Petersen, 1990).

Inhibition and disinhibition of return: evidence from temporal order judgments.

In the present study the temporal order judgment (TOJ) task was used to investigate whether or not inhibition of return (IOR) affects perceptual processing. Previous failures to obtain IOR in the TOJ task have been taken to suggest that IOR does not affect perceptual processing (e.g., Maylor, 1985). The present study showed that IOR is modulated by the temporal disparity between successive targets as well as the relative order in which they appear at cued and uncued locations. Consequently, IOR affects TOJs in some conditions but not in others. The selective occurrence of IOR in the TOJ task provides converging support for the notion that IOR does affect perceptual processing, and also accounts for the previous failures to observe IOR in the TOJ task. Moreover, these and other results suggest that inhibitory processing at the cued location can be dis-inhibited when stimulation occurs at other locations.

Variation in cue duration reveals top-down modulation of involuntary orienting to uninformative symbolic cues

This article reports three experiments in which the effects of cue duration on involuntary orienting to uninformative symbolic cues (arrows presented at fixation) were investigated. Experiment 1 showed that symbolic cues had less effect on involuntary orienting when they were presented for only 25 msec than when they were presented for 200 msec across a range of stimulus onset asynchronies. Experiment 2 suggested that the effect of cue duration on involuntary orienting was due primarily to top-down strategic factors, rather than to bottom-up stimulus factors, and Experiment 3 suggested that these strategic factors may involve differences in how the cue is processed. Altogether, the present findings are important because they emphasize the distinction between cue processing and the putative involuntary orienting that results from such processing in the symbolic-cuing paradigm. In so doing, the present results help resolve discrepant findings that have been reported across previous studies.