The manner in which Pressey's assimilation theory of geometric illusions (e.g., Pressey & Pressey, 1992) operates is illustrated by considering the basic question of why shrinkage and expansion forms of Müller-Lyer's illusions differ. The traditional answer is that the differences are due to the fact that the two forms generate “fundamentally different” kinds of illusions. Three experiments, each purporting to support this view, were simulated by the quantitative version of the theory. Because the theory correctly predicted complex means and variances, it was concluded that the traditional position was not valid.
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References
1.
AdamJ.BatemanL. (1980) Control stimuli in investigations of the acute-angled and obtuse-angled Müller-Lyer illusions. Perception, 9, 467–474.
2.
BayerC. A.PresseyA. W. (1972) Geometric illusions as a function of pigmentation of the Fundus oculi and target size. Psychonomic Science, 26, 77–79.
3.
BeagleyW. K. (1985) Interaction of Müller-Lyer with filled-unfilled space illusion: An explanation of Müller-Lyer asymmetry. Perception & Psychophysics, 37, 45–49.
4.
BinetA. (1895) La mèsure des illusions visuèlles chez les enfants. Revue Pilosophique, 40, 11–25.
5.
BrigellM.UhlarikJ. (1979) The relational determination of length illusions and after effects. Perception, 8, 187–197.
6.
BrigellM.UhlarikJ.GoldhornP. (1977) Contextual influences and illusions of extent. Journal of Experimental Psychology: Human Perception & Performance, 3, 105–118.
7.
BrossM.BlairR.LongtinP. (1978) Assimilation theory, attentive fields and the Müller-Lyer illusion. Perception, 7, 297–304.
8.
CapraF. (1983) The Tao of physics. Glasgow, UK: William Collins, Sons.
9.
DayR. H.DickensonR. G. (1976) Apparent length of the arms of acute and obtuse angles, and the components of the Müller-Lyer illusion. Australian Journal of Psychology, 28, 137–148.
10.
EricksenC. W.YehY. (1985) Allocation of attention in the visual field. Journal of Experimental Psychology: Human Perception & Performance, 11, 583–597.
11.
Greist-BousquetS.SchiffmanH. R. (1981) The many illusions of the Müller-Lyer: Comparisons of the wings-in and wings-out illusions and manipulations of standard and dot forms. Perception, 10, 147–154.
12.
JordanK.RandallJ. (1987) The effects of framing ratio and oblique length on Ponzo illusion magnitude. Perception & Psychophysics, 41, 435–439.
13.
JordanK.SchianoD. J. (1986) Serial processing and the parallel lines illusion: Length contrast through relative spatial separation of contours. Perception & Psychophysics, 40, 384–390.
14.
JordanK.UhlarikJ. (1986) Length contrast and the Mueller-Lyer figure: Functional equivalence of temporal and spatial separation. Perception & Psychophysics, 39, 267–274.
15.
KerstenB.SarrisV.KolbertJ. (1987) Predicted gap effects for the Mueller-Lyer figure: A test of two quantitative models. Unpublished manuscript.
16.
LewisE. O. (1909) Confluxion and contrast effects in the Mueller-Lyer illusion. British Journal of Psychology, 3, 21–41.
PiagetJ. (1969) The mechanisms of perception. New York: Routledge & Kegan Paul.
19.
PredebonJ. (1994) The reversed Müller-Lyer illusion in conventional and in wing-amputated Müller-Lyer figures. Psychological Research, 56, 217–223.
20.
PresseyA. W. (1970a) An assimilation theory of geometric illusions. In PresseyA. W.ZubekJ. P. (Eds.), Readings in general psychology: Canadian contributions. Toronto, ON: McClelland & Stewart.
21.
PresseyA. W. (1970b) The assimilation theory applied to a modification of the Müller-Lyer illusion. Perception & Psychophysics, 8, 411–412.
22.
PresseyA. W. (1972) The assimilation theory of geometric illusions: An additional postulate. Perception & Psychophysics, 11, 28–30.
23.
PresseyA. W. (1977) Measuring the Titchener Circles and Delboeuf illusions with the method of adjustment. Bulletin of the Psychonomic Society, 10, 118–120.
24.
PresseyA. W. (1985) The role of internal contextual features in the Baldwin illusion. In McGaughJ. L. (Ed.), Contemporary psychology: Biological processes and theoretical issues. Amsterdam, The Netherlands: Elsevier.
25.
PresseyA. W. (1987) Psychophysical methods and life-span changes in visual illusions. Perceptual & Motor Skills, 65, 83–87.
26.
PresseyA. W.ButchardN.ScrivnerL. (1971) Assimilation theory and the Ponzo illusion: Quantitative predictions. Canadian Journal of Psychology, 25, 486–497.
27.
PresseyA. W.DiLolloV. (1978) Effects of distance between standard and comparison lines on the Müller-Lyer illusion. Perception & Psychophysics, 24, 415–419.
PresseyA. W.KerstenB. (1989) Attention and the Muller-Lyer illusion: Simulation of an experiment by Larsen and Garn. Perceptual & Motor Skills, 68, 1323–1329.
30.
PresseyA. W.MoroT. L. (1971) An explanation of Cooper and Runyon's results on the Mueller-Lyer illusion. Perceptual & Motor Skills, 32, 564–566.
31.
PresseyA. W.MurrayR. (1976) Further developments in the assimilation theory of geometric illusions. Perception & Psychophysics, 19, 536–544.
32.
PresseyA. W.PresseyC. A. (1992) Attentional fields are related to focal and contextual features: A study of Müller-Lyer distortions. Perception & Psychophysics, 51, 423–436.
33.
PresseyA. W.SmithN. E. (1986) The effects of location, orientation, and cumulation of boxes in the Baldwin illusion. Perception & Psychophysics, 40, 344–350.
34.
PresseyA. W.WilsonA. E. (1977) The hydra-headed Müller-Lyer effect: A theoretical puzzle. Perception & Psychophysics, 22, 392–394.
35.
PresseyA. W.WilsonA. E. (1980) Assimilation theory and the Baldwin illusion. The Italian Journal of Psychology, 7, 65–73.
36.
RestleF.DeckerJ. (1977) Size of the Mueller-Lyer illusion as a function of its dimensions: Theory and data. Perception & Psychophysics, 21, 489–503.
37.
SchianoD. J. (1986) Relative size and spatial separation: Effects on the parallel lines illusion. Perceptual & Motor Skills, 63, 1151–1155.
38.
SekulerR.BlakeR. (1985) Perception. New York: Alfred A. Knopf.
39.
SekulerR.ErlebacherA. (1971) The two illusions of Müller-Lyer: Confusion theory reexamined. American Journal of Psychology, 84, 477–486.
40.
SweeneyO. (1973) Successive trials effects in the two forms of the Müller-Lyer illusion. Unpublished doctoral dissertation, Univer. of Manitoba, Winnipeg, Canada.
41.
WeintraubD. J.KrantzD. H. (1971) The Poggendorff illusion: Amputations, rotations, and other perturbations. Perception & Psychophysics, 10, 257–264.
42.
WilsonA. E. (1981) Contrast and assimilation in illusions of extent. Unpublished doctoral dissertation, Univer. of Manitoba, Winnipeg, Canada.
43.
WilsonA. E.PresseyA. W. (1988) Contrast and assimilation in the Baldwin illusion. Perceptual & Motor Skills, 66, 195–204.
