Abstract
The magnitude of the Mueller-Lyerillusion was measured under conditions of high and low image blur. Blur was manipulated by altering the focus of an image projected on a screen. Elusion magnitude increased under high blur conditions. This supports the theory that blur-inducing optical imperfections of the eye are partially responsible for illusory effects in figures with converging lines. The data also indicate the importance of testing the acuity of observers in such experiments, since poor refraction can result in artifactual overestimation of illusion magnitude.
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This research was supported in part by grants from the National Research Council of Canada A9783 and A9958. The authors would also like to thank Donna Bevelander who assisted on the statistical analyses.
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Ward, L.M., Coren, S. The effect of optically induced blur on the magnitude of the Mueller-Lyer illusion. Bull. Psychon. Soc. 7, 483–484 (1976). https://doi.org/10.3758/BF03337255
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DOI: https://doi.org/10.3758/BF03337255