Sunday, January 29, 2012

On Right Angles

Most humans seem to have a natural impulse to create right angles, and will do so despite attempted conscious override. For example, when trying to draw figure 1, most people will draw figure 2 instead. Figures 3 and 4 are more examples. Notice the right angles that are created in the incorrect examples.

Even after a person has been told of this phenomenon, they will continue to perform the same mistake. See figures 5-7: When given instructions to add “cross-contour lines” to figure 5, the typical subject will produce figure 7, not figure 6. Once again, the tendency to make the lines 'increasingly perpendicular' is evident.

Relevant Findings:
The following is taken from a relevant report; subjects were shown various angles and asked what angle they saw:
Compared to a quadrilateral on its own, judgments of the acute and obtuse angles in the cube drawings were biased towards 90 degrees.

Of interest, the judgments are attracted only to 90
degrees, not to 0 degrees or 180 degrees, 45 degrees and 135 degrees,other possible components of good form. angle illusion could be a top-down, Gestalt effect. When physical conditions approach a ‘simpler’ shape, a percept with symmetry, equality, parallels, and orthogonality is favoured, Gestaltists argue.

If the V means 90 degrees, it is seen as 90 degrees, in a strong version of this theory.

Peterson and Gibson (1993) argue perceptual input and cognitive information are processed in parallel. If recognition influences perception, angles close to 90 degrees on the page might indeed be seen as 90 degrees.
Angle illusion on a picture’s surface
University of Toronto at Scarborough, 1265 Military Trail, Toronto ON M1C1A4, Canada
Received 28 August 2006; accepted 15 March 2007

Spatial Vision, Vol. 21, No. 3–5, pp. 451– 462 (2008)
Koninklijke Brill NV, Leiden, 2008.

Also available online -

Peterson, M. A. and Gibson, B. S. (1993). Shape recognition contributions to figure-ground organization in three-dimensional displays, Cognit. Psychol. 25, 383–429.

Further Interpretations:
In an effort towards simplification, where all angles exist on a spectrum between 90 and 180 degrees, (either angled or straight) it is 'cognitively efficient' to assume that the angle in question is not somewhere on the angle-spectrum, but only at either end. To see things as either good or bad, right or wrong, up or down, is also much easier and at times more effective than discriminating between shades of difference.

In another override (also, one would assume, to maximize cognitive processing), it is, at times (or, more often than not, as it seems) better to "see" what a thing "is" rather than to see what it really looks like. (This implies that the viewer knows that the correctly-drawn cube is, in fact, a cube, with six rectilinear sides, just by looking at the drawing, thus knowing what it is, or is meant to represent.)

So, is this common misperception a result of simple-over-complex, or one of "what it is" over "what it looks like"

The Nature of Illusion

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