Quantal fluctuation limitations on reaction time to sinusoidal gratings

A model of sinusoidal grating detection based on the output of many parallel-processing spatial frequency-bandpass receptive fields is developed. The receptive fields are assumed to be of similar shape but to differ in scale and retinal location. Because the retinal image is inherently noisy due to photon noise a signal detection analysis is carried out. For a stimulus grating having a particular spatial frequency there is a most sensitive mechanism: one with a receptive field of ideal size and retinal location with respect to the stimulus. We hypothesize that subjects make reliable judgements concerning the physical presence of a grating based on the time-integrated output of the most sensitive mechanism. This leads to the prediction that reaction time to grating onset will be linearly related to the square of the grating frequency. This prediction is confirmed by data from Breitmeyer [1975, Experiment 1 (Vision Res. 15, 1411-1412)].