Vicarious conditioned acceleration: successful observational learning of an aversive Pavlovian stimulus contingency

Five rats (observers) were trained to avoid unsignalled shocks in a shuttlebox and then habituated to brief light presentations. They were next confined on an observation platform while another rat (model) received light-shock pairings in the opposite compartment. The observers were exposed only to the sight and sound of the model during classical conditioning and were not shocked themselves. Test presentations of the light during subsequent avoidance sessions produced response rate increases (vicarious conditioned acceleration) comparable to those obtained in other studies where the avoidance animals were used in classical conditioning. Following sessions in which the model was not shocked after the light, the light presentations during avoidance eventually failed to elicit any response increases in the observers. When the model was again shocked, immediate recovery of avoidance acceleration occurred in the observers during the light.