The choice between two groups of human vision functional models: multi-channel and its modifications and the models based on the conception of matched filtering in the human visual system is difficult because predictions made by using each of these models are very close to experimental data. One of exceptions is the dependence of contrast sensitivity on the number (N) of sine-wave grating cycles when N is small and spatial frequency is constant. According to matched filtering models reduction of N specifies the proportional reduction in contrast sensitivity. According to multi-channel models reduction in N specifies the more strong reduction in contrast sensitivity than in the first case, since when N decreases, the spatial-frequency spectrum of test grating expands and therefore the energy corresponding to the appropriate channel decreases because of energy redistribution between all channels. Hence, the more energy is need for test grating detection with given probability than it is obtained in the experiments. Performed calculations and comparison their results with experimental data permit us to prefer the matched filtering model for description and modeling of the human- display interactions.