Voluntarily controlled bi–stable slant perception of real and photographed surfaces

Abstract

We have quantified voluntarily selected perceived slant of real trapezoidal surfaces (a 'reverse-perspective' scene) and their photographed counterparts (pictorial space). The surfaces were slanted about the vertical axis and observers estimated slant relative to the frontal plane. We were particularly interested in those cases in which binocular disparity and monocular perspective provided conflicting slant information. We varied the monocularly and binocularly specified surface slants independently across stimulus presentations. To eliminate texture and shading cues we used sand-blasted aluminium trapezoidal surfaces illuminated from all directions. When disparity-specified slant and perspective-specified slant were conflicting, observers were able to perceive the surfaces in two ways: they perceived either a trapezoid or a rectangle. Our main finding is twofold. First, when subjects chose to perceive the trapezoid, the slant estimates followed the disparitypredicted slant with only a slight underestimation, as if they selected a pure binocular representation of slant governed only by disparity. Second, when subjects chose to perceive the rectangle their estimates for real surfaces were similar to those for photographed surfaces, as if they selected a representation of slant governed by perspective foreshortening.

The role of (micro)saccades and blinks in perceptual bi-stability from slant rivalry

“…Moreover, two alternating slants were perceived when perspective-and disparity-specified quite different slants. Our results are similar to those reported previously for slants about a vertical axis (van Ee et al, 2003;van Ee et al, 2002;van Ee et al, 2005b). In experiment 2 we investigated gaze positions while subjects viewed the stimulus and found that eye movements were not essential for the instigation of a perceptual flip, which means that perceptual flips were governed by a cognitive process.…”

“…The perceived slants about the horizontal axis are similar to those found previously for slants about the vertical axis (van Ee, Adams, & Mamassian, 2003;van Ee et al, 2002;van Ee, Krumina, Pont, & van der Ven, 2005b). In other words the perceived slants can be understood in a Bayesian frame work that describes the quantitative aspects of perceived slant on the basis of the likelihoods of both perspective and disparity slant information combined with prior assumptions about the shape and orientation of objects in the scene (van Ee et al, 2003).…”

The Role of Linear Perspective Cues on the Perceived Depth Magnitude of the Surfaces They are Painted on: Proper-, Reverse-, and Flat-Perspective Paintings

“…Recently, Erkelens (2013a) conducted a comprehensive study with both opposite-and same-signed slants specified by disparity and perspective cues and provided evidence that binocular disparity played no role in determining the final percept. However, most of these studies dealt with either (a) quantitative assessments (magnitude of slant or depth) using computerdisplayed stimuli (Allison and Howard, 2000;Dosher et al, 1986;Erkelens, 2013aErkelens, , 2013bSato & Howard, 2001;van der Meer, 1979;van Ee et al, 2002van Ee et al, , 2003 or (b) qualitative scene layout perception using physical 3-D stimuli (Cook et al, 2002;Keane, Silverstein, Wang, & Papathomas, 2013;Papathomas, 2002;Papathomas, Baker, Yeshua, Zhuang, & Ng, 2012;Rogers & Gyani, 2010;Sherman, Papathomas, Jain, & Keane, 2011;van Ee, Krumina, Pont, & van der Ven, 2005). To our knowledge, only van Ee et al (2005) studied quantitative aspects of slant using physical planar stimuli.…”