[Forward and reverse connections in the presence of a combination of indifferent stimuli]

In pairing of auditory and photic stimuli, the first stimulus caused an orientation reaction typical of the second stimulus even before its action, while the "proper" reaction to the first stimulus was reduced. Difference between orientation reactions to "positive" and "differentiation" stimuli was revealed. If the "positive" stimulus evoked the orientation reaction typical of the second stimulus, and the proper reaction was weakened, then the differentiation stimulus elicited mainly the proper reaction or no orientation reaction at all. This seems to be due to the specialization of reactions of performed by means forward connection.