The effect of instrumentalization of inborn reaction on its transformation into contrary directed escape response in dogs and the problem of reinforcement.

Transformation of inborn reaction of leg flexion into conditioned escape response of leg extension was studied. The model of the so called precise reflex was used. A dog could avoid or escape the shock applied to the paw by placing this paw in a narrow ,,safety zone located at a definite height above the floor. When the shock is applied to the paw located below this zone, the escape response is flexion, i.e., it coincides with the inborn reaction. When the paw is lifted above this zone, the escape response is extension, i.e., it is opposite to the inborn response. Success of such extension response acquisition depended on the sequence of training conditions. The dogs of Group I at the beginning were accustomed to escape from shock by lifting the paw into the ,,safety zone, i.e., inborn reaction was instrumentalized. A subsequent formation of conditioned extension was extremely difficult and it did not became strong in spite of a very long training. Lowering the paw into the ,,safety zone was usually slow. The dogs of group II were trained from the very beginning to escape from shock by leg extension. Contrary to the results obtained on group I this conditioned response was perfectly established. It was formed rapidly, only when active extension was paired regularly with termination (during extension) of the shock. It is suggested that conditioned connection from one functional center to another is formed and becomes stronger if evoked activity of the first center decreases during (or immediately after) the excitation of the second center.