June 2007
Volume 7, Issue 9
Free
Meeting Abstract  |   June 2007
Entasis: architectural illusion compensation, aesthetic preference or engineering necessity?
Author Affiliations
  • Peter Thompson
    Department of Psychology, University of York, York, UK.
  • Georgia Papadopoulou
    Department of Psychology, University of York, York, UK.
  • Eleni Vassilou
    Department of Psychology, University of York, York, UK.
Journal of Vision June 2007, Vol.7, 355. doi:10.1167/7.9.355
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      Peter Thompson, Georgia Papadopoulou, Eleni Vassilou; Entasis: architectural illusion compensation, aesthetic preference or engineering necessity?. Journal of Vision 2007;7(9):355. doi: 10.1167/7.9.355.

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      © 2015 Association for Research in Vision and Ophthalmology.

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Abstract

A typical characteristic of columns in Doric temples is entasis; a slight convexity in the body of the column. Often, particularly in guide-books, it is suggested that entasis compensates for an illusion of concavity in columns with parallel sides. Architectural experts generally agree: Entasis is the “swelling given to a column in the middle parts of the shaft for the purpose of correcting a disagreeable optical illusion, which is found to cause their outlines to seem concave instead of straight”- Penrose (1888). Nuttgens (1999) writes ‘Most Greek buildings of this golden period use entasis, the device whereby columns are given a slight swelling .… to counteract a tendency of the eye to see them as curving inwards from either side..’

We investigated whether any such illusion exists in a series of experiments in which we vary the degree of entasis from a negative value (columns waisted in the middle) through parallel sides to positive values (columns bulging in the middle). Our experiments presented 7 stimuli; 3 convex, 3 concave and 1 with truly parallel columns in a constant stimuli paradigm. Each stimulus was presented 30 times (to 12+ subjects) in pseudo-random order and results plotted as a psychometric function from which the PSE where columns appear neither convex nor concave determined. Several experiments, with more or less realistic column stimuli, failed to find any evidence to support any illusion-compensation theory.

Secondly, we have explored the possibility that entasis was employed for purely aesthetic reasons. 5 computer-generated temples were judged for their aesthetic preference by 30 subjects. The temples differed in the application of entasis on the columns: 2 had negative entasis, 2 positive and one had parallel-sided columns. The results showed positive entasis as the least preferred aesthetically.

Finally, we shall present some evidence supporting an engineering role for entasis.

Thompson, P. Papadopoulou, G. Vassilou, E. (2007). Entasis: architectural illusion compensation, aesthetic preference or engineering necessity? [Abstract]. Journal of Vision, 7(9):355, 355a, http://journalofvision.org/7/9/355/, doi:10.1167/7.9.355. [CrossRef]
© 2007 ARVO
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