STUDIES OF CLASSICAL HEART RATE CONDITIONING IN THE RAT,

Four rat heart rate conditioning studies are presented. Measures were 1 HR changes during 8 sec. CS 9550 cps tone and 2 immediately after the CS when the UCS 0.5 sec. shock was not presented. Using analysis of variance, significant evidence of conditioning was found. The CR was a cardiac deceleration on early trials each day, followed by a cardiac accelera tion on later trials. The orienting response to tone was found to show similar changes as a function of trials. It was concluded that pre vous investigators would have also observed conditioned acceleration had they given a larger number of conditioning trials. The data were viewed as consistent with a stimulus substitu tion theory of conditioning, although other hypotheses were not ruled out. Author