Two principles of perception revealed by geometrical illusions

Day, R. H.

doi:10.1080/00049530601087504

Cited by 8 publications

(7 citation statements)

References 22 publications

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“…For example, the lines of an equilateral triangle in which all the angles are acute appear shorter than those of the same length in a pentagon in which all the angles are obtuse. Day (2006) extended these observations by showing that lines, also of the same length, forming a square appear intermediate in length between those of the triangle and pentagon and, moreover, that the same differences are evident in the equal dimensions of other figures . In consequence it was concluded that the apparent length of lines forming a figure is determined by the overall size of the figure of which they are integral parts.…”

Section: Critical Role Of Oblique Intersectionsmentioning

confidence: 70%

On the common stimulus condition and explanation of the Müller-Lyer, Poggendorff and Zöllner illusions: The basis for a class of geometrical illusions

Day

2010

Australian Journal of Psychology

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Although the Mü ller-Lyer, Poggendorff and Zö llner figures and the illusions with which they are associated-those of length, misalignment and non-parallelism, respectively -are quite different, all three are attributable to the same basic effect, that of the difference in the apparent length of equal lines forming acute and obtuse angles. The role of this basic affect, reported originally by Mü ller-Lyer but overlooked by him and others as a possible cause of the three illusions, is identified and discussed. It is suggested that the demonstration of a basic stimulus condition (acute and obtuse angles) and its associated illusion (difference in apparent length) generating a class of ''higher order'' geometric illusions has implications not only for a closer understanding of the three illusions under consideration but for other classes of illusory phenomena that might also share a common basis.

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Section: Critical Role Of Oblique Intersectionsmentioning

confidence: 70%

On the common stimulus condition and explanation of the Müller-Lyer, Poggendorff and Zöllner illusions: The basis for a class of geometrical illusions

Day

2010

Australian Journal of Psychology

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“…This is a striking variation on a theme by Botti ( 1906 ). (n) Another illusion by Day ( 2006 ). The half segments belonging to the cross are equal to the sides of the diamond, but appear to be longer.…”

Section: The Corpus Of Geometrical Illusionsmentioning

confidence: 99%

“…He illustrated his principle with Figures 15–19 of his panel, but there are, in my opinion, other principles at work in his examples. Day ( 2006 ) conjectured that “it is conceivable that (…) the amount of time it takes to move from one place to another is a determinant of the apparent distance between them.”—but he did not speculate on the law relating space and time.…”

Section: Measurement Theories Of Illusionsmentioning

confidence: 99%

Geometrical illusions are not always where you think they are: a review of some classical and less classical illusions, and ways to describe them

Ninio

2014

Front. Hum. Neurosci.

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Geometrical illusions are known through a small core of classical illusions that were discovered in the second half of the nineteenth century. Most experimental studies and most theoretical discussions revolve around this core of illusions, as though all other illusions were obvious variants of these. Yet, many illusions, mostly described by German authors at the same time or at the beginning of the twentieth century have been forgotten and are awaiting their rehabilitation. Recently, several new illusions were discovered, mainly by Italian authors, and they do not seem to take place into any current classification. Among the principles that are invoked to explain the illusions, there are principles relating to the metric aspects (contrast, assimilation, shrinkage, expansion, attraction of parallels) principles relating to orientations (regression to right angles, orthogonal expansion) or, more recently, to gestalt effects. Here, metric effects are discussed within a measurement framework, in which the geometric illusions are the outcome of a measurement process. There would be a main “convexity” bias in the measures: the measured value m(x) of an extant x would grow more than proportionally with x. This convexity principle, completed by a principle of compromise for conflicting measures can replace, for a large number of patterns, both the assimilation and the contrast effects. We know from evolutionary theory that the most pertinent classification criteria may not be the most salient ones (e.g., a dolphin is not a fish). In order to obtain an objective classification of illusions, I initiated with Kevin O'Regan systematic work on “orientation profiles” (describing how the strength of an illusion varies with its orientation in the plane). We showed first that the Zöllner illusion already exists at the level of single stacks, and that it does not amount to a rotation of the stacks. Later work suggested that it is best described by an “orthogonal expansion”—an expansion of the stacks applied orthogonally to the oblique segments of the stacks, generating an apparent rotation effect. We showed that the Poggendorff illusion was mainly a misangulation effect. We explained the hierarchy of the illusion magnitudes found among variants of the Poggendorff illusion by the existence of control devices that counteract the loss of parallelism or the loss of collinearity produced by the biased measurements. I then studied the trapezium illusion. The oblique sides, but not the bases, were essential to the trapezium illusion, suggesting the existence of a common component between the trapezium and the Zöllner illusion. Unexpectedly, the trapeziums sometimes appeared as twisted surfaces in 3d. It also appeared impossible, using a nulling procedure, to make all corresponding sides of two trapeziums simultaneously equal. The square-diamond illusion is usually presented with one apex of the diamond pointing toward the square. I found that when the figures were displayed more symmetrically, the illusion was significantly reduced. Fur...

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“…Incidentally, there is evidence that the distortions in a number of illusions (Zöllner, Poggendorff and Müller-Lyer) critically depend on the presence of corner junctions (e.g. Day, 2006) and that errors on a Müller-Lyer shaft bisection task increase close to the angles (Prebedon, 2000). Thus, one of the future directions of this research will be to systematically relate the strength of this illusion to the degree of field distortion…”

Section: Discussionmentioning

confidence: 99%

Local spatial distortion caused by simple geometrical figures

Aksentijevic

Elliott

2017

Quarterly Journal of Experimental Psychology

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Dynamic distortion of the visual field has been shown to affect perceptual judgment of visual dimensions such as size, length, and distance. Here, we report four experiments demonstrating that the different aspects of a triangle differently influence judgments of distance. Specifically, when the base of the triangle faces the centre of the display, participants consistently underestimate and overestimate the distance of a small dot from the unmarked centre of the display relative to conditions in which the vertex of the triangle faces the centre. When the dot is close to the figure, the distance of the dot to the centre is underestimated. Conversely, when the dot is close to the figure, the distance to the centre is overestimated. The effect is replicated when the internal distances are equalized and when ellipses are used instead of triangles. These results support a ripple model of spatial distortion in which local curvature acts to attract or repel objects. In conclusion, we suggest some implications of our findings for theories of perceptual organization.

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Two principles of perception revealed by geometrical illusions

Cited by 8 publications

References 22 publications

On the common stimulus condition and explanation of the Müller-Lyer, Poggendorff and Zöllner illusions: The basis for a class of geometrical illusions

On the common stimulus condition and explanation of the Müller-Lyer, Poggendorff and Zöllner illusions: The basis for a class of geometrical illusions

Geometrical illusions are not always where you think they are: a review of some classical and less classical illusions, and ways to describe them

Local spatial distortion caused by simple geometrical figures

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