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The venetian-blind effect: a preference for zero disparity or zero slant?

Vlaskamp BN, Guan P, Banks MS - Front Psychol (2013)

Bottom Line: The preference for minimum disparity and minimum slant are identical for gaze at zero eccentricity; we dissociated the predictions of the two by measuring the occurrence of Venetian blinds when the stimuli were viewed in eccentric gaze.The results were generally quite consistent with a zero-disparity preference (Experiment 1), but we also observed a shift toward a zero-slant preference when the edges of the stimulus had zero slant (Experiment 2).These observations provide useful insights into how the visual system constructs depth percepts from a multitude of possible depths.

View Article: PubMed Central - PubMed

Affiliation: Vision Science Program, School of Optometry, University of Berkeley Berkeley, CA, USA ; Philips Research Eindhoven, Netherlands.

ABSTRACT
When periodic stimuli such as vertical sinewave gratings are presented to the two eyes, the initial stage of disparity estimation yields multiple solutions at multiple depths. The solutions are all frontoparallel when the sinewaves have the same spatial frequency; they are all slanted when the sinewaves have quite different frequencies. Despite multiple solutions, humans perceive only one depth in each visual direction: a single frontoparallel plane when the frequencies are the same and a series of small slanted planes-Venetian blinds-when the frequencies are quite different. These percepts are consistent with a preference for solutions that minimize absolute disparity or overall slant. The preference for minimum disparity and minimum slant are identical for gaze at zero eccentricity; we dissociated the predictions of the two by measuring the occurrence of Venetian blinds when the stimuli were viewed in eccentric gaze. The results were generally quite consistent with a zero-disparity preference (Experiment 1), but we also observed a shift toward a zero-slant preference when the edges of the stimulus had zero slant (Experiment 2). These observations provide useful insights into how the visual system constructs depth percepts from a multitude of possible depths.

No MeSH data available.


Related in: MedlinePlus

The sunbeam illusion or crepuscular rays. The sun shines through clouds creating regions of illumination and shadow. The beams appear to radiate from a central point much as the blades of a fan emanate from a center. The perceptual effect is striking in the natural environment when the viewer looks with one eye while not moving the head. Image: Andrew Green “over the lighthouse,” December 13, 2010 via Flickr, Creative Commons Attribution.
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Figure 2: The sunbeam illusion or crepuscular rays. The sun shines through clouds creating regions of illumination and shadow. The beams appear to radiate from a central point much as the blades of a fan emanate from a center. The perceptual effect is striking in the natural environment when the viewer looks with one eye while not moving the head. Image: Andrew Green “over the lighthouse,” December 13, 2010 via Flickr, Creative Commons Attribution.

Mentions: The photograph in Figure 2 shows rays of sunlight shining through clouds. The rays appear to radiate like a fan from a central point; the fan appears to lie in a plane perpendicular to the viewer's line of sight. The same effect occurs in the natural environment when viewed with one eye and a stationary head. Despite the appearance of a fan-like pattern, the rays are actually all parallel to the line of sight because their source is the sun, which is effectively at infinite distance. Nonetheless, the rays regress perceptually toward a fronto-parallel plane, so they appear to lie in a surface of zero slant even though their true geometry is parallel rays with slants close to 90°. This effect has been called the sunbeam illusion or crepuscular rays (Minnaert, 1954; Lynch, 1987).


The venetian-blind effect: a preference for zero disparity or zero slant?

Vlaskamp BN, Guan P, Banks MS - Front Psychol (2013)

The sunbeam illusion or crepuscular rays. The sun shines through clouds creating regions of illumination and shadow. The beams appear to radiate from a central point much as the blades of a fan emanate from a center. The perceptual effect is striking in the natural environment when the viewer looks with one eye while not moving the head. Image: Andrew Green “over the lighthouse,” December 13, 2010 via Flickr, Creative Commons Attribution.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3822326&req=5

Figure 2: The sunbeam illusion or crepuscular rays. The sun shines through clouds creating regions of illumination and shadow. The beams appear to radiate from a central point much as the blades of a fan emanate from a center. The perceptual effect is striking in the natural environment when the viewer looks with one eye while not moving the head. Image: Andrew Green “over the lighthouse,” December 13, 2010 via Flickr, Creative Commons Attribution.
Mentions: The photograph in Figure 2 shows rays of sunlight shining through clouds. The rays appear to radiate like a fan from a central point; the fan appears to lie in a plane perpendicular to the viewer's line of sight. The same effect occurs in the natural environment when viewed with one eye and a stationary head. Despite the appearance of a fan-like pattern, the rays are actually all parallel to the line of sight because their source is the sun, which is effectively at infinite distance. Nonetheless, the rays regress perceptually toward a fronto-parallel plane, so they appear to lie in a surface of zero slant even though their true geometry is parallel rays with slants close to 90°. This effect has been called the sunbeam illusion or crepuscular rays (Minnaert, 1954; Lynch, 1987).

Bottom Line: The preference for minimum disparity and minimum slant are identical for gaze at zero eccentricity; we dissociated the predictions of the two by measuring the occurrence of Venetian blinds when the stimuli were viewed in eccentric gaze.The results were generally quite consistent with a zero-disparity preference (Experiment 1), but we also observed a shift toward a zero-slant preference when the edges of the stimulus had zero slant (Experiment 2).These observations provide useful insights into how the visual system constructs depth percepts from a multitude of possible depths.

View Article: PubMed Central - PubMed

Affiliation: Vision Science Program, School of Optometry, University of Berkeley Berkeley, CA, USA ; Philips Research Eindhoven, Netherlands.

ABSTRACT
When periodic stimuli such as vertical sinewave gratings are presented to the two eyes, the initial stage of disparity estimation yields multiple solutions at multiple depths. The solutions are all frontoparallel when the sinewaves have the same spatial frequency; they are all slanted when the sinewaves have quite different frequencies. Despite multiple solutions, humans perceive only one depth in each visual direction: a single frontoparallel plane when the frequencies are the same and a series of small slanted planes-Venetian blinds-when the frequencies are quite different. These percepts are consistent with a preference for solutions that minimize absolute disparity or overall slant. The preference for minimum disparity and minimum slant are identical for gaze at zero eccentricity; we dissociated the predictions of the two by measuring the occurrence of Venetian blinds when the stimuli were viewed in eccentric gaze. The results were generally quite consistent with a zero-disparity preference (Experiment 1), but we also observed a shift toward a zero-slant preference when the edges of the stimulus had zero slant (Experiment 2). These observations provide useful insights into how the visual system constructs depth percepts from a multitude of possible depths.

No MeSH data available.


Related in: MedlinePlus