Poster Session I: Diurnal variations in luminance and chromatic contrast sensitivity.

Abstract

Sensory motor performance typically peaks in the evening, influenced by observer's diurnal arousal level. The arousal level is regulated by neurons in the brainstem, which form connections extending throughout the brain but the connection is highly heterogeneous. The dorsal visual pathway and superior colliculus receive a dense projections, while the ventral visual pathway and lateral geniculate nucleus receive fewer. The former primarily deal with stimuli determined by luminance contrast, while the latter handle chromatic information. How such heterogeneous projection in the brain impacts on human visual detection performance has yet to be understood. In this study, we measured the diurnal variation in human contrast sensitivity and investigated whether changes differed between luminance and chromatic stimuli. Result revealed that as the time of day progressed, sensitivity to luminance contrast improved, while sensitivity to color contrast deteriorated.