An Explanation for the Müller-Lyer Illusion

This article describes a quantitative method to evaluate several averaging (i,e., confusion and assimilation) theories by comparing predictions of the absolute magnitude of the Muller-Lyer (ML) illusion with results of previous studies of the composite ML figure. The magnitude of illusion was best predicted by Davies and Spencer's (1977) theory and by integrative field theory (Pressey & Pressey, 1992). Furthermore, when the ML figure was at the point of subject equality, the average of shaft and intertip distances, and the configural dimensions proposed by Davies and Spencer, were most frequently closest to being equal in the apex-in ML and apex-out ML. Results indicate that a comparison ofpredicted and reported absolute magnitudes ofthe ML illusion can provide quantitative criteria to distinguish and evaluate averaging theories of the ML illusion.

Section: Methodsmentioning

confidence: 87%

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confidence: 84%

A quantitative analysis of illusion magnitude predicted by several averaging theories of the Müller-Lyer illusion

DeLucia

1993

“…Experimental results indicate that there are systematic relations between certain aspects of the Muller-Lyer figure and it's perceived size. For instance, experiments in which the geometrical properties of the figure were varied have led to good insight in to the effects of variation of angle and length of the oblique lines (Davies & Spencer, 1977;Restle & Decker, 1977).…”

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confidence: 99%

Influence of color and luminance on the Müuller-Lyer illusion

Sadza

Weert

1984

The arrowheads and lines of the Milller-Lyer illusion were varied independently in color and luminance. Stimuli were presented on a computer-controlled color television monitor. Subjects responded yes or no to a forced choice. Results indicated the following: (1) Differences in color between arrowheads and line reduce the illusion. (2) Luminance differences between arrowheads and line always reduce the illusion. (3) Effect 1 and 2 are independent of each other. (4) With a dark background, if the arrowheads are brighter than the line, the decrease is smaller than when the arrowheads are darker than the line. (5) A total change of luminance does not affect the illusion. Results 1 and 2 contradict Wickelgren's contrast hypothesis, which predicts a maximum illusion with the difference between arrowheads and background at maximum and the difference between line and background at minimum. Result 4, however, shows that an explanation in terms of similarity only is not possible. Therefore, a description in terms of both contrast and similarity is proposed.

“…Davies and Spencer (1977) stress the experimental fact that, with fin angles of 30 to 60 deg and with moderate fin lengths, the magnitude of the distortion of length is very accurately proportional to m cos a.…”

Section: Comparison With Experimental Datamentioning

confidence: 99%

“…For this reason, we will restrict ourselves to the Muller-Lyer patterns in this range and we will use data accumulated by Davies and Spencer (1977) and Restle and Decker (1977).…”

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confidence: 99%

Two-dimensional filtering, oriented line detectors, and figural aspects as determinants of visual illusions

Eijkman

Jongsma

Vincent

1981

Quantitative data of Muller-Lyer illusions from the literature were analyzed according to three different models. All three models predict the illusion effect, although with different magnitude and different parameter dependency. First, a filter model describing a certain amount of blurring of the retinal picture seems partly responsible for the observed illusion. With reasonable estimation of the filter constants, however, a sufficient magnitude of illusion cannot be obtained. A second model of oriented line or bar receptors is even less effective in explaining the observed length illusions. A third model, consisting of a size-constancy operator triggered by depth cues, may predict effects larger than actually observed. It is concluded that figural aspects such as depth-inducing cues are mainly responsible for the illusion effects observed in Muller-Lyer figures.