In order to study the correlation of the brightness enhancement nearthe edge transition and the effect of the broad area, experiments were carried out on the effect of simultaneous masking of the edge and the change of the threshold contrast for the low spatial frequencies by masking the suprathreshold grating having the high spatial frequencies. The results suggest that the contrast thresholds of low frequency components rose with masking by the high contrast pattern of high frequency components.
A model is assumed in which the spatial brightness enhancements are the result of the interactions of four kinds of spatial brightness signals in the visual system, that is, outputs of ‘ narrow receptive fields’, ‘broad receptive fields’, ‘differential detectors’ and ‘gradient detectors’. The model based on these four signals are discussed.