Novelty, arousal, and the reinforcement of diversive exploration in the rat.

Abstract

In 1 experiment, training sessions, during which a bar press resulted in either a novel or a familiar light change or buzzer sound, and test sessions, during which no reinforcing stimulus was given, occurred on alternate days. For rats maintained in a noisy room, novel stimuli were more rewarding than familiar stimuli, but the opposite was true for rats maintained in a quiet room. It is suggested that reward value is an inverted U-shaped function of arousal value, which increases with the novelty of the stimulus and the arousal level of Sfsubject]. This suggestion was corroborated by the results of a 2nd experiment, with methamphetamine injections used to raise arousal.