Distortions of perceived length in the frontoparallel plane: Tests of perspective theories

Abstract

The perceived length of a line segment in a frontoparallel plane is sometimes affected by the presence of other line segments in the visual field. Perspective theories attribute such interactions to sizeconstancy scaling: The configuration of line segments present in the visual field includes depth cues that trigger size scaling of each line segment. In three experiments, we test this claim for a range of simple configurations composed of two line segments joined at a point. These configurations include the inverted T configuration of the bisection illusion, as well as the L configuration of the horizontalvertical illusion. We conclude that the available depth cues, even when supplemented by known biases in perspective interpretations, do not account for observed distortions in judgments of relative length.

A scaling analysis of the snake lightness illusion

“…We draw the reader's attention to an analogous finding in the literature on pictorial illusions of length in Wolfe, Maloney, and Tam (2005), who concluded that illusory distortions of perceived line length cannot be attributed to a single depth interpretation of the pictured scene. It is also plausible that the visual system has no consistent interpretation of such pictured scenes.…”

Length perception of horizontal and vertical bisected lines

“…The results demonstrated that the degree of vertical overestimation directly depended on the degree of asymmetry, reaching its maximum when the horizontal bisection was symmetric (inverted T conWguration) and its minimum when the two lines formed a L shape. More recently, Wolfe et al (2005) conducted an experiment very similar to that of Künnapas and they also observed that the symmetry or asymmetry of bisection determines the degree of vertical overestimation. Although none of the studies proposed theoretical accounts to support their data, they both showed that the symmetry of bisection was determinant in line length perception.…”

“…Several studies suggesting that the visual Weld's shape has an impact on the vertical bias, reported that the vertical overestimation is signiWcantly reduced under monocular viewing condition, in comparison to binocular viewing (Künnapas, 1957a, b;Prinzmetal & Gettleman, 1993). It has recently been concluded that the size-constancy scaling mechanisms and the visual Weld anisotropy have independent eVects on the vertical bias (Williams & Enns, 1996) but that none of the two theories could account for the amount of the vertical overestimation in some two-line conWgurations (see Wolfe et al, 2005).…”

“…In this Wgure, two lines of the same length are displayed in an L or T shape on a two-dimensional background. The vertical line is reported as being longer whenever it is compared to a horizontal one (see adjustment and production tasks, Brosvic & Cohen, 1988;Harris & Slotnick, 1996;Lipshits & McIntyre, 1999;Lipshits, McIntyre, Zaoui, GurWnkel, & Berthoz, 2001;Wolfe & Amis, 2006; judgment tasks, Dixon & ProYtt, 2002;Künnapas, 1955a;Wolfe, Maloney, & Tam, 2005; reaching and grasping tasks, Raudsepp & Djupsjöbacka, 2005;Vishton, Rea, Cutting, & Nunez, 1999; tasks using inverting prisms, Richter, Wennberg & Raudsepp, 2007;haptic tasks, Gentaz & Hatwell, 2004 and tasks using auditory substitution of vision, Renier, Bruyer, & De Volder, 2006). A large body of evidence indicates that the vertical overestimation is highly dependent on the conWguration of the two lines.…”

Titchener’s ⊥ in context 1—delimited, discrete monomotif patterns, line arrangements, and branching patterns

“…Prinzmetal & Gettleman, 1993) and, with regard to possible effects of phenomenal perspective (von Collani, 1985), Ward, Porac, Coren, and Girgus (1977) could not find substantial evidence for a three-dimensional (3D) interpretation of the ⊥-figure (cf. Wolfe, Maloney, & Tam, 2005, for a formal experimentum crucis). Although there have been several proposals for a general, neurophysiological account of visual illusions (e.g., Fermüller & Malm, 2004: neural noise; Ganz, 1964: lateral inhibition), none has picked Titchener's ⊥ as its prime example, or offered a detailed explanation of the ⊥-illusion.…”