Purchase this article with an account.
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: https://doi.org/10.1167/5.12.88.
Download citation file:
© ARVO (1962-2015); The Authors (2016-present)
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.
This PDF is available to Subscribers Only