Contrast coding and magno/parvo segregation revealed in reaction time studies.
Reaction times (RTs) are obtained for a wide range of contrasts of vertical sinusoidal gratings. The data are plotted as a function of the reciprocal of contrast. In some conditions, a single linear function accounts for the data. In others a clear bi-linear function is obtained. The low and high contrast regions of the function are interpreted as representing magno and parvo activity, respectively. RT-based supra-threshold sensitivity functions are obtained for different luminances, stimulus durations and eccentricities and these are compared with conventional threshold-based sensitivities to establish the extent to which RTs and contrast sensitivity are constrained by the same sensory processes.
Murray
I J
IJ
Visual Sciences Laboratory, Department of Optometry and Neuroscience, UMIST, PO Box 88, Manchester M60 1QD, UK. mjcijm@fsl.op.umist.ac.uk
Plainis
S
S
D003118:Color Perception / Q000502:physiology; D015350:Contrast Sensitivity / Q000502:physiology*; D005829:Geniculate Bodies / Q000502:physiology*; D006801:Humans; D011930:Reaction Time; D014794:Visual Fields; D014795:Visual Pathways / Q000502:physiology; D014796:Visual Perception / Q000502:physiology