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Effect of chromatic mechanisms on the detection of mesopic incremental targets at different eccentricities
Author(s) -
Bodrogi Peter,
Vas Zoltán,
Haferkemper Nils,
Várady Géza,
Schiller Christoph,
Khanh Tran Quoc,
Schanda János
Publication year - 2010
Publication title -
ophthalmic and physiological optics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.147
H-Index - 66
eISSN - 1475-1313
pISSN - 0275-5408
DOI - 10.1111/j.1475-1313.2009.00699.x
Subject(s) - achromatic lens , mesopic vision , chromatic scale , optics , visibility , physics , metric (unit) , chromatic adaptation , contrast (vision) , sensitivity (control systems) , biological system , mathematics , photopic vision , biology , retina , operations management , electronic engineering , economics , engineering
Spectral sensitivity functions for the threshold detection of mesopic incremental targets were compared for different target eccentricities (10, 20, and 30°) 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°. 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°, the visibility predicted by C CHC2 is less than the visibility predicted by C MOVE .