A Theory of the Mueller-Lyer Illusion

Pressey, Alexander W.

doi:10.2466/pms.1967.25.2.569

Cited by 69 publications

(33 citation statements)

References 3 publications

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“…The literature on humans offers at least two theories that may account for the illusion: perspective theory (Gregory, 1963) and assimilation theory (Pressey, 1967(Pressey, , 1971.…”

Section: Resultsmentioning

confidence: 99%

Pigeons see the Ponzo illusion

Fujita

Blough

1991

Animal Learning & Behavior

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Three experiments were performed to address factors contributing to the Ponzo illusion. In Experiment 1, pigeons learned to peck at the longer of two bars in varying line contexts. When these lines converged, the birds had difficulty in learning several patterns in which a Ponzo illusion would reduce the perceived difference. In Experiment 2, the subjects chose one response if a stimulus bar was longer than a predetermined length and a second response for shorter bars. The subjects were more likely to choose "long" as the stimulus bar approached the apex of converging lines. These results suggested that pigeons experience the Ponzo illusion. In Experiment 3, the effects of contexts that did and did not form a texture gradient were compared. The magnitude ofthe illusion did not differ according to context lines. This result failed to support a perspective theory of the Ponzo illusion. 283Studies of form pereeption in nonhuman speeies have demonstrated both similarities and dissimilarities with form perception in hurnans. For example, judgments about letter similarity are alike in pigeons, nonhurnan primates, and hurnans (Blough, 1982(Blough, , 1985Matsuzawa, 1985). On the other hand, recent evidenee indieates that pigeons and humans respond differently to eertain features of forms in visual seareh tasks (Allan & Blough, 1989).An interesting aspeet of pattern pereeption eoneerns geometrie illusions. Although rnany researehers have been interested in illusory pereeption by humans and many different geometrie illusions have been diseovered, there are few reports of illusory effects in nonhuman animals. Several studies suggest that monkeys are suseeptible to geometrie illusions: Dominguez (1954) showed that monkeys experienee a horizontal-vertieal illusion in whieh vertieallines are judged to be longer than horizontallines ofthe same length; Dominguez (1954) and Harris (1968, cited in Davis, 1974 demonstrated that monkeys are likely to see rectangles as being taller than squares (breadth-ofrectangles illusion); Benhar and Samuel (1982) showed that anubis baboons see a Zötlner illusion, in whieh parallel lines appear to be nonparallel because of the presenee of oblique transverse lines; Bayne and Davis (1983) demonstrated that rhesus monkeys are suseepti-

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“…The literature on humans offers at least two theories that may account for the illusion: perspective theory (Gregory, 1963) and assimilation theory (Pressey, 1967(Pressey, , 1971.…”

Section: Resultsmentioning

confidence: 99%

Pigeons see the Ponzo illusion

Fujita

Blough

1991

Animal Learning & Behavior

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“…30) and the assimilation theory (18,31). The eye-movement theory claimed that the misperception of the central shaft arises from the different extents of eye movements needed to view a figure adorned with arrow tails compared to a figure with arrowheads.…”

Section: Previous Explanations Of the Mü Ller-lyer Effectmentioning

confidence: 99%

“…Although the effects produced by these several variants have not been quantitatively compared, there is a general agreement that the shaft or the corresponding interval in the ''outward'' figure always appears longer than its counterpart in the ''inward'' figure. As a result, there has been much controversy about the genesis of the Müller-Lyer effect (6,(10)(11)(12)(13)(14)(15)(16)(17)(18)(19)(20), which still has no generally accepted explanation (21,22).…”

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The Müller-Lyer illusion explained by the statistics of image–source relationships

Howe

Purves

2005

Proc. Natl. Acad. Sci. U.S.A.

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The Mü ller-Lyer effect, the apparent difference in the length of a line as the result of its adornment with arrowheads or arrow tails, is the best known and most controversial of the classical geometrical illusions. By sampling a range-image database of natural scenes, we show that the perceptual effects elicited by the Mü llerLyer stimulus and its major variants are correctly predicted by the probability distributions of the possible physical sources underlying the relevant retinal images. These results support the conclusion that the Mü ller-Lyer illusion is a manifestation of the probabilistic strategy of visual processing that has evolved to contend with the uncertain provenance of retinal stimuli.geometrical illusions ͉ natural scene statistics ͉ vision T he standard Müller-Lyer stimulus (Fig. 1A) has been the subject of hundreds of studies since its introduction in the late 19th century (1). The perceptual effect is that two identical straight lines appear different in length when they are terminated, respectively, with ''arrowheads'' that extend inward or ''arrow tails'' that extend outward with respect to the ''shaft.'' Although there is considerable variation in the reported magnitude of the effect (presumably due to the different experimental conditions in various studies), the line terminated by the arrowheads always appears shorter than same line terminated by arrow tails (2-8).Rationalizing this illusion has been made especially difficult by persistence of the effect when the identical lines are terminated with a variety of other adornments (9), a fact that undermines intuitive explanations based on what arrowheads and tails might signify. In Fig. 1B, for instance, the same perceptual discrepancy is generated when identical lines are terminated by outward and inward squares. A further obstacle for any simple explanation of the Müller-Lyer effect is that neither the shaft (Fig. 1C) nor continuous lines (Fig. 1D) is needed to elicit a misperception of the relevant spatial interval. Although the effects produced by these several variants have not been quantitatively compared, there is a general agreement that the shaft or the corresponding interval in the ''outward'' figure always appears longer than its counterpart in the ''inward'' figure. As a result, there has been much controversy about the genesis of the Müller-Lyer effect (6,(10)(11)(12)(13)(14)(15)(16)(17)(18)(19)(20), which still has no generally accepted explanation (21,22).Here we test the hypothesis that the standard Müller-Lyer effect and its variants are a result of the fundamentally probabilistic strategy of visual processing that contends with inverse optics problem. Any geometrical stimulus (or indeed any visual stimulus) can have been generated by many different real-world sources (23-27), presenting a quandary to observers whose survival depends on appropriate visually guided behavior. A plausible solution would be to generate visual percepts predicated on the probability distributions of the physical sources of retinal images. In t...

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“…Massaro and Anderson (1971). Pressey (1967). and Restle and Merryman (1968) have all presented data which suggest the operation of corn par at ive judgmental componen ts in iIlusion formation.…”

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confidence: 99%