Reaction time as a measure of temporal summation at suprathreshold levels

Two subjects performed simple reaction-time responses to green-blue stimuli of varying luminance and duration under binocular and monocular observation. Reaction time varied as a power function of luminance with simple fractional exponents: an exponent of 1/3 for binocular vision and an exponent of 2/5 for monocular vision. The luminance required to produce ten criterion reaction times was calculated, and the luminance-duration relationship was examined. The critical duration was a function of the criterion reaction time: as the criterion reaction time increases, the critical duration increases monotonically. The binocular critical duration was found to be longer than the monocular critical duration.