title: Characterising mesopic spectral sensitivity from reaction times.
abstract: The spectral sensitivity of the eye was investigated using reaction times to broadband chromatic stimuli over a range of background luminances. Relative sensitivity was determined from the nonlinear reaction time curve by converting reaction times to a linear measure that was independent of spectral sensitivity. Two models for mesopic spectral sensitivity were compared. The first was a linear combination of V(lambda) and V'(lambda), and the second included input from the L-M colour-opponent mechanism and the S-cones. The second model produced a significantly better fit to the data. The chromatic mechanisms appear to contribute to reaction time when there is an appreciable chromatic signal but luminance contrast is low.
authors.affiliation: Applied Vision Research Centre, The Henry Wellcome Laboratories for Vision Sciences, City University, London, EC1V 0HB, UK. h.walkey@imperial.ac.uk <h.walkey@imperial.ac.uk>
authors.forename: H C
authors.initials: HC
authors.lastname: Walkey
authors.forename: J A
authors.initials: JA
authors.lastname: Harlow
authors.forename: J L
authors.initials: JL
authors.lastname: Barbur
mesh_terms: D000221:Adaptation, Ocular; D000328:Adult; D003118:Color Perception / Q000502:physiology; D015350:Contrast Sensitivity / Q000502:physiology; D005260:Female; D006801:Humans; D008027:Light; D008297:Male; D008433:Mathematics; D008960:Models, Psychological; D010775:Photic Stimulation / Q000379:methods; D010783:Photometry; D011601:Psychophysics; D011930:Reaction Time; D012684:Sensory Thresholds; D014796:Visual Perception / Q000502:physiology*