Illusory contours induced by isoluminant chromatic patterns

Ejima, Yoshimichi; Takahashi, Shingo

doi:10.1016/0042-6989(88)90068-5

Cited by 17 publications

(12 citation statements)

References 26 publications

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“…Their paradigm thus did not provide a direct metric of IC sensitivity. By contrast, Ejima and Takahashi (1988) showed that ICs can be reliably perceived when defined by chromatic contrast. Our current results provide direct evidence for the ability of ICs based on both luminance and chromaticity differences to elicit IC perception.…”

Section: Brain Mechanisms Of Ic Sensitivity Across Types Of Contrastmentioning

confidence: 99%

“…The extent to which the spatio-temporal brain dynamics of the IC sensitivity are cue-dependent and impacted by stimulus features, such as luminance and chromaticity, remains unknown. Resolving the role of these stimulus features in IC sensitivity would provide much-needed insights into potentially differing contributions of magnocellular versus parvocellular subdivisions of the visual system to IC sensitivity (Ejima and Takahashi, 1988;Gregory, 1977;Li and Guo, 1995;Soriano et al, 1996) as well as potentially reconcile the discrepant findings and the resultant models of IC sensitivity.…”

Section: Introductionmentioning

confidence: 99%

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Cue-dependent circuits for illusory contours in humans

et al. 2016

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Objects' borders are readily perceived despite absent contrast gradients, e.g. due to poor lighting or occlusion. In humans, a visual evoked potential (VEP) correlate of illusory contour (IC) sensitivity, the "IC effect", has been identified with an onset at ~90ms and generators within bilateral lateral occipital cortices (LOC). The IC effect is observed across a wide range of stimulus parameters, though until now it always involved high-contrast achromatic stimuli. Whether IC perception and its brain mechanisms differ as a function of the type of stimulus cue remains unknown. Resolving such will provide insights on whether there is a unique or multiple solutions to how the brain binds together spatially fractionated information into a cohesive perception. Here, participants discriminated IC from no-contour (NC) control stimuli that were either comprised of low-contrast achromatic stimuli or instead isoluminant chromatic contrast stimuli (presumably biasing processing to the magnocellular and parvocellular pathways, respectively) on separate blocks of trials. Behavioural analyses revealed that ICs were readily perceived independently of the stimulus cue -i.e. when defined by either chromatic or luminance contrast. VEPs were analysed within an electrical neuroimaging framework and revealed a generally similar timing of IC effects across both stimulus contrasts (i.e. at ~90ms). Additionally, an overall phase shift of the VEP on the order of ~30ms was consistently observed in response to chromatic vs. luminance contrast independently of the presence/absence of ICs. Critically, topographic differences in the IC effect were observed over the ~110-160ms period; different configurations of intracranial sources contributed to IC sensitivity as a function of stimulus contrast. Distributed source estimations localized these differences to LOC as well as V1/V2. The present data expand current models by demonstrating the existence of multiple, cue-dependent circuits in the brain for generating perceptions of illusory contours.

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Section: Brain Mechanisms Of Ic Sensitivity Across Types Of Contrastmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Cue-dependent circuits for illusory contours in humans

et al. 2016

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“…Most researchers have reported the absence of illusory contours when inducers are isoluminant with the background (de Weert, 1983;Gregory, 1977;Livingstone & Hubel, 1988;Watanabe & Sato, 1989), although Ejima and Takahashi (1988) noted that illusory contours generated by abutting line gratings (as in Figure 2c) can be perceived under certain isoluminant conditions. De Weert (1983) presented a detailed study ofthe effect of color and color differences on illusory contour formation.…”

Section: Low-level Determinantsmentioning

confidence: 99%

Illusory contours: Toward a neurally based perceptual theory

Lesher

1995

Psychon Bull Rev

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Although illusory contours were first described nearly a century ago, researchers have only recently begun to approach a consensus on the processes underlying their formation. Neurophysiological and psychophysical evidence indicate that neural mechanisms of the early visual cortex subserve illusory contour generation, although cognitive factors play important roles in determining the fmal percept. I summarize experiments concerning the determinants of illusory contour strength and form, concentrating on findings particularly relevant to modeling. After establishing arguments for the early generation of illusory contours, I provide an overview of formation theories, culminating with descriptions of neural models. The constraints that experimental data place on models are outlined, and neural models are evaluated with respect to these constraints. Throughout the review,I indicate where further experimental and modeling research are critical.Schumann introduced the first illusory contour, depicted in Figure 1a, in 1900, noting that a central "white rectangle with sharply defined contours appears, which objectively are not there." Schumann had discovered and noted two salient features of illusory figures: sharp edges in regions of homogeneous luminance, and a brightening within the figure. Perhaps because this stimulus failed to yield particularly convincing illusory contours, it was not until more than 50 years later that illusory contours became a topic for activeresearch. Although Ehrenstein (1941) demonstrated stimuli with salient illusory contours, it is remarkable that he failed to note their existence in the text of his article explicitly, commenting instead only on illusory brightening effects. Kanizsa's (1955) stunning figures, examples of which are depicted in Figures Iband 1c, produced extremely sharp, salient contours along with obvious brightening, initiating a wave of research.Although there have been a number ofexcellent illusory contour review papers Meyer & Petry, 1987;Parks, 1984), research advances in the psychophysical, neurophysiological, and modeling domains have been more than sufficient to mandate a new summary ofthe literature. Inthis review, I will not only present more recent data, but also employ an approach to the summaries that is markedly different from those previously taken. At the time of the earlier reviews, determination of the locus of formation of illusory contours was the central issue in illusory contour research, a fact reflected in the structure of the review papers. Experimental results were presented primarily in the historical context of supporting or refut-I would like to thank Ennio Mmgolla of Boston University for generously providing many helpful comments and suggestions during the development ofthis review.

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“…Previous work suggests that inducer contrast is directly related to illusory contour strength (Ejima & Takahashi, 1988;Gregory, 1977;Petry et al, 1983). Therefore, we explored this effect by utilizing perceived visibility as our measure of illusory contour strength.…”

Section: Experiments 4 Effect Of Inducer Contrastmentioning

confidence: 99%