Illusory bands in orientation and spatial frequency: a cortical analog to Mach bands.
Illusory bands at a luminance transition in space (ie an edge) are well known. Here we demonstrate illusory bands of enhanced orientations or spatial frequencies at transitions between higher-contrast and lower-contrast image content along the orientation and spatial-frequency dimensions--the dimensions of cortical spatial coding. We conclude that this illusion is a consequence of cortical-level suppression of units of similar orientations and spatial frequencies and serves to aid texture segmentation while providing efficient neural coding.
Essock
Edward A
EA
Department of Psychological and Brain Sciences, University of Louisville, Louisville, KY 40292, USA. essock@louisville.edu
Hansen
Bruce C
BC
Haun
Andrew M
AM
D015350:Contrast Sensitivity / Q000502:physiology; D006801:Humans; D008027:Light; D009903:Optical Illusions / Q000502:physiology*; D009949:Orientation / Q000502:physiology*; D010364:Pattern Recognition, Visual / Q000502:physiology*; D010783:Photometry; D013028:Space Perception