title: Effect of chromatic mechanisms on the detection of mesopic incremental targets at different eccentricities.
abstract: Spectral sensitivity functions for the threshold detection of mesopic incremental targets were compared for different target eccentricities (10, 20, and 30 degrees ) and for different mesopic backgrounds (0.1, 0.5 and 1.0 cd m(-2)). Relative responsivities of achromatic mechanisms (L + M and rods) and chromatic mechanisms (S and /L-M/) were estimated for each eccentricity and background. Chromatic mechanisms contribute significantly to detection but their effect is lower at 30 degrees . A new contrast metric (C(CHC2)) is introduced to account for the selective adaptation of the photoreceptors and the effects of the chromatic mechanisms i.e. broadening of the range of spectral sensitivity with multiple local maxima and yellow sub-additivity of detection performance. The C(CHC2) metric is compared with the achromatic contrast metric of the MOVE model (C(MOVE)). For the same target, C(CHC2) generally predicts a higher visibility level than C(MOVE). However, in accordance with visual observations, for grey or yellowish incremental targets appearing at the eccentricities of 20 and 30 degrees , the visibility predicted by C(CHC2) is less than the visibility predicted by C(MOVE).
authors.affiliation: FG Lichttechnik, Technische Universität Darmstadt, Hochschulstrasse 4a, Darmstadt, Germany. bodrogi@lichttechnik.tu-darmstadt.de
authors.forename: Peter
authors.initials: P
authors.lastname: Bodrogi
authors.forename: Zoltán
authors.initials: Z
authors.lastname: Vas
authors.forename: Nils
authors.initials: N
authors.lastname: Haferkemper
authors.forename: Géza
authors.initials: G
authors.lastname: Várady
authors.forename: Christoph
authors.initials: C
authors.lastname: Schiller
authors.forename: Tran Quoc
authors.initials: TQ
authors.lastname: Khanh
authors.forename: János
authors.initials: J
authors.lastname: Schanda
mesh_terms: D003118:Color Perception / Q000502:physiology*; D003119:Color Perception Tests; D003198:Computer Simulation; D015350:Contrast Sensitivity / Q000502:physiology; D004192:Discrimination, Psychological; D006801:Humans; D008027:Light; D008433:Mathematics; D008954:Models, Biological; D010775:Photic Stimulation; D012684:Sensory Thresholds / Q000502:physiology*