Applying the Helmholtz illusion to fashion: horizontal stripes won’t make you look fatter

Peter Thompson

Department of Psychology, University of York, York, YO10 5DD UK

Kyriaki Mikellidou

Department of Psychology, University of York, York, YO10 5DD UK

   

Abstract. A square composed of horizontal lines appears taller and narrower than an identical square made up of vertical lines. Reporting this illusion, Hermann von Helmholtz noted that such illusions, in which filled space seems to be larger than unfilled space, were common in everyday life, adding the observation that ladies’ frocks with horizontal stripes make the figure look taller. As this assertion runs counter to modern popular belief, we have investigated whether vertical or horizontal stripes on clothing should make the wearer appear taller or fatter. We find that a rectangle of vertical stripes needs to be extended by 7.1% vertically to match the height of a square of horizontal stripes and that a rectangle of horizontal stripes must be made 4.5% wider than a square of vertical stripes to match its perceived width. This illusion holds when the horizontal or vertical lines are on the dress of a line drawing of a woman. We have examined the claim that these effects apply only for 2-dimensional figures in an experiment with 3-D cylinders and find no support for the notion that horizontal lines would be ‘fattening’ on clothes. Significantly, the illusion persists when the horizontal or vertical lines are on pictures of a real half-body mannequin viewed stereoscopically. All the evidence supports Helmholtz’s original assertion.


Cite as: Thompson P, Mikellidou K, 2011, "Applying the Helmholtz illusion to fashion: horizontal stripes won’t make you look fatter" i-Perception 2(1) 69–76; doi:10.1068/i0405
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DOI: 10.1068/i0405

ISSN: 2041-6695 (electronic only)

Copyright: Copyright is retained by the author(s) of this article. This open-access article is distributed under a Creative Commons Licence, which permits noncommercial use, distribution, and reproduction, provided the original author(s) and source are credited and no alterations are made.
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