San Lorenzo and the Poggendorff illusion in Ravenna

DANEYKO, Olga, STUCCHI, Natale and ZAVAGNO, Daniele (2011). San Lorenzo and the Poggendorff illusion in Ravenna. i-Perception, 2 (5), 502-507.

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In the Mausoleum of Galla Placidia (Ravenna, Italy), the San Lorenzo lunette shows two peculiar visual effects: a transparency effect of gold seen through gold and perceptual collinearity between two parts of a cross which are physically misaligned. Both effects are found within the area of the halo surrounding the saint’s head. In this work we addressed the problem posed by the physical misalignment of the cross. Our hypothesis is that the physical misalignment went unnoticed throughout history because the artist produced a perceptual alignment to correct for the Poggendorff illusion. Hence, we asked observers to align two ends of a cross in a reproduction showing the silhouette of San Lorenzo’s torso holding the cross. Results support our hypothesis: both direction and magnitude of adjustments comply with the alignment in the original mosaic.

Item Type: Article
Research Institute, Centre or Group - Does NOT include content added after October 2018: Cultural Communication and Computing Research Institute > Art and Design Research Centre
Departments - Does NOT include content added after October 2018: Faculty of Social Sciences and Humanities > Department of Psychology, Sociology and Politics
Identification Number:
Page Range: 502-507
Depositing User: Olga Daneyko
Date Deposited: 17 Jan 2018 12:06
Last Modified: 18 Mar 2021 07:19

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