Reaction time to motion onset: local dispersion model analysis.

Data on the simple reaction time to motion onset presented in Ball and Sekuler [Psychol. Rev. 87, 435-469 (1980)] and Tynan and Sekuler [Vision Res. 20, 709-715 (1982)] are re-analysed on the basis of local dispersion model of motion detectability. According to this model the detectability at the moment t is determined by the mean value of the local dispersion function LD (t) within the interval (t-T, t), LD(t) being some measure of scattering (namely, running variance) of spatial positions passed through during the period (t-tau, t). Reaction time is assumed to be equal to the time that takes the detectability to reach some critical level plus constant execution time. Theoretical predictions fit the experimental data perfectly when two main parameters of the model, T/tau and tau are the same as were found appropriate in other, independent experiments on motion detection.