Global shape versus local feature: An angle illusion

Kennedy, Graeme J.; Orbach, Harry S.; Löffler, Günter

doi:10.1016/j.visres.2008.03.003

Cited by 17 publications

(18 citation statements)

References 40 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Area V2 contributes to angle information extraction by a linear combination of orientation selective V1 cells' outputs (Hegdé and Van Essen, 2000; Boynton and Hegdé, 2004; Ito and Komatsu, 2004). Angle discrimination and judgment of the visual system is highly dependent on global geometry of the object containing them (Kennedy et al, 2006, 2008). Curvatures and orientation flows of real and illusory contours also activate three dimensional and complex shape processing mechanisms in extra-striate cortical areas (Pasupathy and Connor, 1999, 2001; Li et al, 2008; Filangieri and Li, 2009).…”

Section: Discussionmentioning

confidence: 99%

Adaptation to Skew Distortions of Natural Scenes and Retinal Specificity of Its Aftereffects

Habtegiorgis

Rifai

Lappe³

et al. 2017

Front. Psychol.

View full text Add to dashboard Cite

Image skew is one of the prominent distortions that exist in optical elements, such as in spectacle lenses. The present study evaluates adaptation to image skew in dynamic natural images. Moreover, the cortical levels involved in skew coding were probed using retinal specificity of skew adaptation aftereffects. Left and right skewed natural image sequences were shown to observers as adapting stimuli. The point of subjective equality (PSE), i.e., the skew amplitude in simple geometrical patterns that is perceived to be unskewed, was used to quantify the aftereffect of each adapting skew direction. The PSE, in a two-alternative forced choice paradigm, shifted toward the adapting skew direction. Moreover, significant adaptation aftereffects were obtained not only at adapted, but also at non-adapted retinal locations during fixation. Skew adaptation information was transferred partially to non-adapted retinal locations. Thus, adaptation to skewed natural scenes induces coordinated plasticity in lower and higher cortical areas of the visual pathway.

show abstract

Section: Discussionmentioning

confidence: 99%

Adaptation to Skew Distortions of Natural Scenes and Retinal Specificity of Its Aftereffects

Habtegiorgis

Rifai

Lappe³

et al. 2017

Front. Psychol.

View full text Add to dashboard Cite

show abstract

“…Since the stimuli consisted only of plain triangles set against a uniform grey background, and the only relevant contextual information was the length of the two lines defining the target angle of the triangle, this illusion is not caused by the processing of 3D depth cuesunlike, say, classic demonstrations of shape or size constancy, as in Cohen and Jones (2008) or Ostrofsky et al (2012). (See Kennedy et al, 2008, for the tentative theory that the visual system's computation of the aspect ratio of the entire triangle is the causal mechanism producing this illusion).…”

Section: Angle Drawing As a Test Case Of The Misperception Hypothesismentioning

confidence: 99%

Observational drawing biases are predicted by biases in perception: Empirical support of the misperception hypothesis of drawing accuracy with respect to two angle illusions

Ostrofsky

Kozbelt

Cohen

2015

Quarterly Journal of Experimental Psychology

View full text Add to dashboard Cite

We tested the misperception hypothesis of drawing errors, which states that drawing accuracy is strongly influenced by the perceptual encoding of a to-be-drawn stimulus. We used a highly controlled experimental paradigm in which nonartist participants made perceptual judgements and drawings of angles under identical stimulus exposure conditions. Experiment 1 examined the isosceles/scalene triangle angle illusion; congruent patterns of bias in the perception and drawing tasks were found for 40 and 60° angles, but not for 20 or 80° angles, providing mixed support for the misperception hypothesis. Experiment 2 examined shape constancy effects with respect to reproductions of single acute or obtuse angles; congruent patterns of bias in the perception and drawing tasks were found across a range of angles from 29 to 151°, providing strong support for the misperception hypothesis. In both experiments, perceptual and drawing biases were positively correlated. These results are largely consistent with the misperception hypothesis, suggesting that inaccurate perceptual encoding of angles is an important reason that nonartists err in drawing angles from observation.

show abstract

“…The segments belong to the sides of a perfect hexagon, but seem to be displaced. (g) The triangle illusion of Kennedy et al ( 2008 ). The two angles at the top of the triangles are equal, but the one belonging to the equilateral triangle seems to be larger than the other.…”

Section: The Corpus Of Geometrical 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.

View full text Add to dashboard Cite

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...

show abstract

Global shape versus local feature: An angle illusion

Cited by 17 publications

References 40 publications

Adaptation to Skew Distortions of Natural Scenes and Retinal Specificity of Its Aftereffects

Adaptation to Skew Distortions of Natural Scenes and Retinal Specificity of Its Aftereffects

Observational drawing biases are predicted by biases in perception: Empirical support of the misperception hypothesis of drawing accuracy with respect to two angle 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

Contact Info

Product

Resources

About