A technique is presented for the estimation of the impulse response, based on data from a psychophysical experiment on threshold vision. A two-step method is used for the estimation of the model parameters. The first step is a Hankel matrix approach, and the second an unweighted least squares method. Results of this estimation technique are presented. The model with the estimated parameters corroborates other psychophysical data. The estimates obtained are adequate for the intended purposes of simulation and modeling.