A detailed theory of the detection of sinusoidal gratings displayed with suprathreshold luminous fluctuations is developed by employing a previous model of the visual and decision-making systems. An important feature of the model is the organization of the photoreceptors and decision-making system into a set of parallel, independent photoreceptive field (PRF)-decision center channels that function like a set of parallel spatialfrequency filters, each associated with an independent threshold detector. A technique is proposed for determining the modulation sensitivity functions (MSFs) of single detection channels by obtaining threshold modulation (<i>M</i><sub><i>TN</i></sub>) data at a fixed sinusoidal grating frequency (ν) while varying the center frequency (ν<sub><i>c</i></sub>) of narrow-band luminous fluctuations caused by video noise (V<sub><i>N</i></sub>). The theory predicts that the ratio, at a given ν, of <i>M</i><sub><i>TN</i></sub> obtained as a function of ν<sub><i>c</i></sub> to the <i>M</i><sub><i>TN</i></sub> obtained without V<sub><i>N</i></sub> is proportional to the MSF of the particular channel for which the widths of the excitatory and inhibitory regions of the PRF equal a halfperiod of ν. Good agreement between theoretical curves and experimental data appearing in the literature provides strong corroboration of the theory.
© 1976 Optical Society of AmericaPDF Article