Meta- and paracontrast reveal differences between contour- and brightness-processing mechanisms.
We investigated meta- and paracontrast masking using tasks requiring observers to judge the surface brightness or else the contours of target stimuli. The contour task revealed strongest metacontrast at SOAs shorter than those obtained for the brightness task. Paracontrast revealed related temporal differences between the tasks. Additionally, the paracontrast results support the existence not only of prolonged inhibitory effects but also of facilitatory effects. The combined results comport with the existence of cortical mechanisms for: (i) fast contour processing, (ii) slow surface-brightness processing, (iii) prolonged inhibition, and (iv) facilitation.
Department of Psychology, University of Houston, Houston, TX 77204-5022, USA. brunob@uh.edu
Bruno G
BG
Breitmeyer
Hulusi
H
Kafaligönül
Haluk
H
Oğmen
Lynn
L
Mardon
Steven
S
Todd
Ralph
R
Ziegler
D000328:Adult; D015350:Contrast Sensitivity / Q000502:physiology*; D005260:Female; D005556:Form Perception / Q000502:physiology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D008959:Models, Neurological; D008960:Models, Psychological; D010470:Perceptual Masking / Q000502:physiology*; D010775:Photic Stimulation / Q000379:methods; D011601:Psychophysics; D012165:Retinal Ganglion Cells / Q000502:physiology; D014795:Visual Pathways / Q000502:physiology