December 2005
Volume 5, Issue 12
Free
OSA Fall Vision Meeting Abstract  |   December 2005
fMRI correlates of corner illusions show that BOLD activation varies gradually with corner angle
Author Affiliations
  • Xoana G Troncoso
    Barrow Neurological Institute
  • Peter U Tse
    Dartmouth College
  • Stephen L Macknik
    Barrow Neurological Institute
  • Gideon P Caplovitz
    Dartmouth College
  • Po-Jang Hsieh
    Dartmouth College
  • Alexander A Schlegel
    Barrow Neurological Institute
  • Susana Martinez-Conde
    Barrow Neurological Institute
Journal of Vision December 2005, Vol.5, 88. doi:10.1167/5.12.88
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      Xoana G Troncoso, Peter U Tse, Stephen L Macknik, Gideon P Caplovitz, Po-Jang Hsieh, Alexander A Schlegel, Susana Martinez-Conde; fMRI correlates of corner illusions show that BOLD activation varies gradually with corner angle. Journal of Vision 2005;5(12):88. doi: 10.1167/5.12.88.

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      © ARVO (1962-2015); The Authors (2016-present)

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Abstract

In the 1970's, the op-artist Victor Vasarely produced a series of “nested squares” paintings showing that 90° corners are more salient perceptually than straight edges. Based on this illusion we developed a novel visual illusion, the “Alternating Brightness Star” (ABS), which shows that sharp corners are more salient than shallow corners. Our recent psychophysical studies of the ABS illusion (Troncoso, Macknik & Martinez-Conde, Perception, 2005) revealed a linear relationship between corner brightness and corner angle, with sharp angles leading to stronger illusory percepts and shallow angles leading to weak percepts. Here we explore the BOLD correlates of the ABS illusion in the human cortex. We presented normal volunteers with ABSs of 5 different angles: 15° (sharp corner), 45°, 75°, 105°, and 180° (no corner). The results show that BOLD signal varies parametrically with corner angle throughout the visual cortex, matching previous psychophysical data and offering the first neurophysiological correlates of the ABS illusion. These results may have important consequences for our understanding of corner and angle processing and perception in the human brain.

Troncoso, X. G. Tse, P. U. Macknik, S. L. Caplovitz, G. P. Hsieh, P.-J. Schlegel, A. A. Martinez-Conde, S. (2005). fMRI correlates of corner illusions show that BOLD activation varies gradually with corner angle [Abstract]. Journal of Vision, 5(12):88, 88a, http://journalofvision.org/5/12/88/, doi:10.1167/5.12.88. [CrossRef]
Footnotes
 This project was funded by a Burke Award and NIH R03 MH0609660-01 grant to PUT, and by Barrow Neurological Foundation grants to SM-C and SLM. XGT was a fellow of the University College London Graduate School Fund
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