Interaction between first- and second-order orientation channels revealed by the tilt illusion: psychophysics and computational modelling.
This paper examines the interaction between first- and second-order contours in the orientation domain. Using the simultaneous tilt illusion (TI), we show that the apparent rotation of a vertical test grating away from that of a surrounding inducing grating (repulsion effect) occurs when both the inducing and test grating are either first- or second-order. Furthermore, a significant repulsion effect is obtained when a first-order inducing grating surrounds a second-order test. If lateral inhibitory interactions between populations of orientation selective neurons provides a plausible explanation for orientation repulsion effects [Blakemore, C. B. Carpenter, R. H. S. & Georgeson, M. A. (1970) Nature, 228, 37-39], it is likely that the cue-invariant mechanisms that encodes the orientation of first- and second-order contours also exhibit inhibitory interactions. A two-channel computational model of orientation encoding is presented where one channel encodes only first-order stimuli while the second channel encodes both first- and second-order contours. In addition to predicting the orientation repulsion effects we observed, the model also provides a functional account of orientation attraction effects in terms of the responses of populations of orientation-tuned neurons.
Smith
S
S
Department of Psychology, Macquarie University, Marsfield, NSW 2109, Sydney, Australia. stuarts@vision.bhs.mq.edu.au
Clifford
C W
CW
Wenderoth
P
P
D016009:Chi-Square Distribution; D003198:Computer Simulation; D006801:Humans; D008959:Models, Neurological; D009903:Optical Illusions; D009949:Orientation / Q000502:physiology*; D011601:Psychophysics