The local character of perspective organization

Grünau, Michael W. von; Wiggin, S.; Reed, Maureen J.

doi:10.3758/bf03206335

Cited by 33 publications

(22 citation statements)

References 18 publications

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“…Extended viewing of an unambiguous stimulus biases subsequent perception of ambiguous versions of the same stimulus away from the adapted percept (Virsu, 1975; Harris, 1980; von Grünau et al, 1984; Nawrot and Blake, 1989, 1991). In experiment 1a, we investigated whether this effect occurs with bistable biological motion by adapting observers to biomotion figures that walked with an unambiguous heading direction, and then testing them with bistable versions of the same figures.…”

Section: Resultsmentioning

confidence: 99%

Neural Integration of Information Specifying Human Structure from Form, Motion, and Depth

Jackson¹,

Blake²

2010

J. Neurosci.

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Recent computational models of biological motion perception operate on ambiguous two-dimensional representations of the body (e.g., snapshots, posture templates) and contain no explicit means for disambiguating the three-dimensional orientation of a perceived human figure. Are there neural mechanisms in the visual system that represent a moving human figure's orientation in three dimensions? To isolate and characterize the neural mechanisms mediating perception of biological motion, we used an adaptation paradigm together with bistable point-light (PL) animations whose perceived direction of heading fluctuates over time. After exposure to a PL walker with a particular stereoscopically defined heading direction, observers experienced a consistent aftereffect: a bistable PL walker, which could be perceived in the adapted orientation or reversed in depth, was perceived predominantly reversed in depth. A phase-scrambled adaptor produced no aftereffect, yet when adapting and test walkers differed in size or appeared on opposite sides of fixation aftereffects did occur. Thus, this heading direction aftereffect cannot be explained by local, disparity-specific motion adaptation, and the properties of scale and position invariance imply higher-level origins of neural adaptation. Nor is disparity essential for producing adaptation: when suspended on top of a stereoscopically defined, rotating globe, a context-disambiguated "globetrotter" was sufficient to bias the bistable walker's direction, as were full-body adaptors. In sum, these results imply that the neural signals supporting biomotion perception integrate information on the form, motion, and three-dimensional depth orientation of the moving human figure. Models of biomotion perception should incorporate mechanisms to disambiguate depth ambiguities in two-dimensional body representations.

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Section: Resultsmentioning

confidence: 99%

Neural Integration of Information Specifying Human Structure from Form, Motion, and Depth

Jackson¹,

Blake²

2010

J. Neurosci.

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“…In the bottom-up camp, most researchers have favored an explanation based on the operation of relatively passive, local processes of neural adaptation and recovery that influence perception in a bottom-up manner (e.g., Spitz & Lipman, 1962;von Grünau, Wiggin, & Reed, 1984). Although this view originated in the context of discredited Gestalt assumptions about underlying physiology (Kohler & Wallach, 1944), more recent formulations have related adaptation effects to the fatigue and recovery of localized neural "channels" that often are hypothesized to play a major role in the visual system (e.g., Anstis, Verstraten, & Mather, 1998;Braddick, Campbell, & Atkinson, 1978;Regan, 1982).…”

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confidence: 99%

“…For example, selectively adapting one underlying cortical structure through extended viewing of an unambiguous version of a reversible figure increases the likelihood that the opposite organization will be perceived when an ambiguous version of the same figure is subsequently presented (e.g., Long, Toppino, & Mondin, 1992;Virsu, 1975). The localized nature of the underlying processes is revealed by the finding that the magnitude of adaptation effects declines markedly with the extent to which the adaptation and test stimuli are presented to different retinal locations (Toppino & Long, 1987;von Grünau et al, 1984).…”

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confidence: 99%

Reversible-figure perception: Mechanisms of intentional control

Toppino

2003

Perception & Psychophysics

116

127

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Observers can exert a degree of intentional control over the perception of reversible figures. Also, the portion of the stimulus that is selected for primary or enhanced processing (focal-feature processing) influences how observers perceive a reversible figure. Two experiments investigatedwhether voluntary control over perception of a Necker cube could be explained in terms of intentionally selecting appropriate focal features within the stimulus for primary processing. In Experiment 1, varying observers' intentions and the focus of primary processing produced additive effects on the percentage of time that one alternativewas perceived. In Experiment 2, the effect of varying the focus of primary processing was eliminated by the use of a small cube, but the effect of intention was unaltered. The results indicate that intentional control over perception can be exerted independently of focal-feature processing, perhaps by top-down activation or priming of perceptual representations. The results also reveal the limits of intentional control.

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“…Within the current literature, there are investigators who favor cognitive processes such as learning and problem solving, which may influence illusory reversals in a "top-down" manner (e.g., Girgus, Rock, & Egatz, 1977;Gregory, 1974;Rock, 1975). There are also investigators who favor the more passive or "bottom-up" processes of neural fatigue and recovery among cortical structures as determiners of figural reversal (e.g., Nawrot & Blake, 1989;Palmer & Bucher, 1981;von Grunau, Wiggin, & Reed, 1984). These interpretive differences do not result from any lack of empirical effort.…”

mentioning

confidence: 99%

Prime time: Fatigue and set effects in the perception of reversible figures

Long

Toppino

Mondin

1992

Perception & Psychophysics

115

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Subjects viewed unambiguous versions of both stationary and rotating Necker cube illusions for varying durations prior to the presentation of the standard ambiguous figure. In each case, the subjects were more likely to report the ambiguous figure to be (1) in the same configuration as that ofthe preceding prime following briefpreexposure periods and (2) in the opposite configuration from that of the preceding prime following long preexposure periods. In addition, the number of reversals of the figure during the test period was also strongly related to the duration of the preexposure period, with progressively fewer reversals reported following longer preexposure periods. The results are interpreted as revealing the concurrent roles of "set" effects in the brief preexposure conditions and neural fatigue effects in the long preexposure conditions. Furthermore, the ability of the proposed two-process model to integrate the myriad of empirical effects in the reversible-figure literature is emphasized.

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The local character of perspective organization

Cited by 33 publications

References 18 publications

Neural Integration of Information Specifying Human Structure from Form, Motion, and Depth

Neural Integration of Information Specifying Human Structure from Form, Motion, and Depth

Reversible-figure perception: Mechanisms of intentional control

Prime time: Fatigue and set effects in the perception of reversible figures

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