Classical conditioning of heart-rate deceleration in the rat with continuous and partial reinforcement

Classical conditioning of heart rate was studied in three groups of rats receiving either 100%, 50%, or 0% reinforcement. All groups were given two days of acquisition and one day of extinction. A deceleration in heart rate was observed as the CR for the 100% and 50% groups. The magnitudes of the CRs failed to diminish over 24 extinction trials.