Recovering 3-D Shape: Roles of Absolute and Relative Disparity, Retinal Size, and Viewing Distance as Studied with Reverse-Perspective Stimuli

Dobias, Joshua J; Papathomas, Thomas V.

doi:10.1068/p7409

Cited by 8 publications

(14 citation statements)

References 37 publications

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“…While this codependence of multiple depth cues on distance complicates interpretation of flipping distance, differences between viewing conditions can be used to infer whether or not a manipulated source of depth information helps disambiguate the illusion. Work with reverspectives shows that viewing distance, rather than the absolute disparity magnitudes, is critical in determining reversibility ( Dobias & Papathomas, 2013 ).…”

Section: Introductionmentioning

confidence: 99%

Pinhole Viewing Strengthens the Hollow-Face Illusion

Koessler

Hill

2015

i-Perception

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A hollow (concave) mask appears convex when viewed from beyond a certain distance even when viewed stereoscopically—this is the hollow-face illusion. At close viewing distances, the same mask is seen as hollow even when disparity information is eliminated by monocular viewing. A potential source of nonpictorial, monocular information that favors a veridical percept at close distances is accommodation in conjunction with focus blur. In this article, we used pinhole viewing to minimize this potential source of information and test whether it affects whether a hollow mask is seen as veridical (concave) or illusory (convex). Since monocular viewing also facilitates the illusory (convex) percept, it was included in the design both as a comparison and to test whether any effect of accommodation depends on vergence. Pinhole viewing was found favor the illusory percept, and its effect was at least as large as, and added to, that of monocular viewing. A control experiment using tinted glasses that attenuate illumination at least as much as the pinholes did not strengthen the illusion ruling out explanations in terms of reduced luminance. For pinhole viewing, there was no difference between monocular and binocular conditions. The results are interpreted as evidence that focus driven depth information affects perceived three-dimensional shape at close distances even when other sources of depth information are available. The lack of a difference between monocular and binocular pinhole viewing suggests that, by disrupting accommodation, pinholes may also interfere with linked vergence cues to depth.

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Section: Introductionmentioning

confidence: 99%

Pinhole Viewing Strengthens the Hollow-Face Illusion

Koessler

Hill

2015

i-Perception

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“…It is unlikely, however, that this small 4.5% decrease in viewing distance was responsible for the significant decrease in illusion strength, which was 35.4% (0.42–0.65)/0.65] for the painted and 49.1% (0.27–0.53)/0.53] for the unpainted stimuli in this experiment. For comparison, Dobias and Papathomas (2013) reported that decreasing the viewing distance by a factor of 50% (from 535 to 267.5 cm) for the same painted stimulus used in the present experiment, decreased the illusion strength by only 14.7%. Thus, the difference in illusion strength is likely due, to a major extent, to the convexity bias.…”

Section: Discussionmentioning

confidence: 51%

“…When fixating the “water” mark at the top of the truncated pyramid, which is at 256 (268−12) cm, the distance from the observer is about 4.5% shorter than when fixating the central building corner (at 268 cm). The strength of reverse-perspective illusions has been shown to decrease as the viewing distance decreases ( Dobias & Papathomas, 2013 ; Papathomas, 2002 ; Rogers & Gyani, 2010 ). It is unlikely, however, that this small 4.5% decrease in viewing distance was responsible for the significant decrease in illusion strength, which was 35.4% (0.42–0.65)/0.65] for the painted and 49.1% (0.27–0.53)/0.53] for the unpainted stimuli in this experiment.…”

Section: Discussionmentioning

confidence: 99%

“…When viewing reverse-perspective stimuli ( Wade & Hughes, 1999 ), painted linear perspective cues can compete with bottom-up monocular (motion parallax, shading, lens accommodation) and binocular (disparity, vergence angle) depth cues, thus creating a bistable percept: The bottom-up cues favor the veridical depth arrangement, whereas the perspective cues elicit a depth-inversion illusion (DII), in which distant points on the stimulus appear to be closer than near points and vice versa ( Cook, Hayashi, Amemiya, & Suzuki, Leumann, 2002 ; Cook, Yutsudo, Fujimoto, & Murata, 2008 ; Dobias & Papathomas, 2013 , 2014 ; Hayashi, Umeda, & Cook, 2007 ; Papathomas, 2002 , 2007 ; Papathomas & Bono, 2004 ; Rogers & Gyani, 2010 ; Sherman, Papathomas, Jain, & Keane, 2011 ; Wagner, Ehrenstein, & Papathomas, 2008 ). Similar cases of DII can occur with either a hollow mask ( Gregory, 1970 , 1997 ; Hill & Bruce, 1993 , 1994 ; Hill & Johnston, 2007 ; Matthews, Hill, & Palmisano, 2011 ; Papathomas & Bono, 2004 ) or merely a hollow oval shape (“hollow-potato”; Hill & Bruce, 1994 ; Johnston, Hill, & Carman, 1992 ).…”

Section: Introductionmentioning

confidence: 99%

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Convexity Bias and Perspective Cues in the Reverse-Perspective Illusion

2016

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The present experiment was designed to examine the roles of painted linear perspective cues, and the convexity bias that are known to influence human observers’ perception of three-dimensional (3D) objects and scenes. Reverse-perspective stimuli were used to elicit a depth-inversion illusion, in which far points on the stimulus appear to be closer than near points and vice versa, with a 2 (Type of stimulus) × 2 (Fixation mark position) design. To study perspective, two types of stimuli were used: a version with painted linear perspective cues and a version with blank (unpainted) surfaces. To examine the role of convexity, two locations were used for the fixation mark: either in a locally convex or a locally concave part of each stimulus (painted and unpainted versions). Results indicated that the reverse-perspective illusion was stronger when the stimulus contained strong perspective cues and when observers fixated a locally concave region within the scene.

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“…The interaction of depth cues in perceiving reverspectives is a key question in this area. Thus far, the main cues that have been studied are binocular disparity, linear perspective and motion parallax [5,33,34]. It appears that prior experiences, specifically with retinal perspective projection, play a leading role in the depth-inversion illusion.…”

Section: The Influence Of Prior Experiences On Visual Perceptionmentioning

confidence: 99%

Hughes’s Reverspectives: Radical Uses of Linear Perspective on Non-Coplanar Surfaces

Papathomas

Hughes²

2019

Vision

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Two major uses of linear perspective are in planar paintings—the flat canvas is incongruent with the painted 3-D scene—and in forced perspectives, such as theater stages that are concave truncated pyramids, where the physical geometry and the depicted scene are congruent. Patrick Hughes pioneered a third major art form, the reverse perspective, where the depicted scene opposes the physical geometry. Reverse perspectives comprise solid forms composed of multiple planar surfaces (truncated pyramids and prisms) jutting toward the viewer, thus forming concave spaces between the solids. The solids are painted in reverse perspective: as an example, the left and right trapezoids of a truncated pyramid are painted as rows of houses; the bottom trapezoid is painted as the road between them and the top forms the sky. This elicits the percept of a street receding away, even though it physically juts toward the viewer. Under this illusion, the concave void spaces between the solids are transformed into convex volumes. This depth inversion creates a concomitant motion illusion: when a viewer moves in front of the art piece, the scene appears to move vividly. Two additional contributions by the artist are discussed, in which he combines reverse-perspective parts with forced and planar-perspective parts on the same art piece. The effect is spectacular, creating objects on the same planar surface that move in different directions, thus “breaking” the surface apart, demonstrating the superiority of objects over surfaces. We conclude with a discussion on the value of these art pieces in vision science.

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Recovering 3-D Shape: Roles of Absolute and Relative Disparity, Retinal Size, and Viewing Distance as Studied with Reverse-Perspective Stimuli

Cited by 8 publications

References 37 publications

Pinhole Viewing Strengthens the Hollow-Face Illusion

Pinhole Viewing Strengthens the Hollow-Face Illusion

Convexity Bias and Perspective Cues in the Reverse-Perspective Illusion

Hughes’s Reverspectives: Radical Uses of Linear Perspective on Non-Coplanar Surfaces

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