The Function of Intensity in the Spatial Summation of Subliminal Stimuli in the Retina

Each of 12 rats was subjected to a conventional three-phase behavioral contrast paradigm. No positive behavioral contrast was observed in any S, although 11 rats showed very strong extinction effects. Three rats showed negative induction, eight showed no increase in response rate in the constant component, while one rat showed first a positive then a negative induction effect. The results were discussed in terms of both Reynolds' and Terrace's hypothesis and related to the recent research on autoshaping.