The orienting-exploratory response hypothesis of discriminative conditioning.

Behavioral and electrophysiological manifestations occurring under conditions of spatial discontiguity of CS and reinforcement (or response) are described. It is concluded that the conflict or learning difficulties which arise in such situations are the result of a competition between the signal directed conditioned orienting response and the goal directed approach response which require different or opposite directional movements. Considerations are offered to prove that the complex orienting-exploratory response emerging as a result of reinforcement corresponds to the real conditioned response and accordingly the CS to a new independent goal with comparable attractiveness as the primary (consummative) goal. Arguments are (brought up against the validity of the stimulus substitution theory of signal directed activities. Findings obtained in fimbria-fornix lesioned animals are presented to show that the orienting-exploratory mode of coping with spatial tasks necessitates the intactness of the limbic system. The conclusion is drawn that an apparently more adaptive mode of behaving in spatial discontiguity, where the CS only releases or triggers the goal response (used occasionally by intact but exclusively by limbic lesioned animals) corresponds to a relatively inferior mode of adaptation.