Visual performance derived from reaction times at low luminance levels: The effect of eccentricity

COLOMBO E.M.; AGUIRRE R.C.; BARRAZA J.F.

Arezzo, Italia

Congreso; European Conference on Visual Perception; 2007

Universidad de Florencia, Dpto. de Psicología

Low luminance and periphery are fundamental aspects in the study of vision in night driving. We investigated how reaction times (RTs) depend on eccentricity for a variety of spatial frequencies and contrasts, considering mesopic adaptation. If RTs are closely related to contrast sensitivity, we expect low and high spatial frequencies to produce different results. We measured RTs as a function of contrast for the detection of achromatic sinusoidal gratings of 1, 2, 4, and 8 cycles deg-1 displayed at 7, 14, and 23 deg of eccentricity besides the foveal condition. Results show that RT increases linearly when it is plotted against the reciprocal of contrast for all eccentricities and spatial frequencies. For 1 and 2 cycles deg-1 the slope of the lines does not depend on eccentricity but RTs at the periphery are all similar and higher than those obtained on the fovea. However, for 4 and 8 cycles deg-1 the slope increases monotonically with eccentricity showing that high spatial frequencies are processed differently at the periphery.