Heart rate and avoidance conditioned activity in rats.

In accordance with the determination of base-line heart rate and running in an activity wheel, 14 Long-Evans male rats were given ten 30 minute sessions of Immobile-Avoid conditioning followed by 30 minute sessions of Active-Avoid conditioning. Control Ss were yoked to the experimental Ss. Experimental Ss made significantly fewer responses in the immobile-avoid period and significantly more responses in the active-avoid period than did the yoked control Ss. Heart rate was correlated with skeletal activity both for experimental and control Ss. For experimental Ss, low heart rate was concomitant with a low amount of activity in the immobile-avoid peroid and high heart rate was concomitant with greater skeletal activity in the active-avoid period. These results support the position that heart rate is secondary to responses of the somatic-motor system and that heart rate during immobile-avoid or active avoid conditioning is more closely related to the level of somatic-motor activity than to the emotional stress which purportedly motivates instrumental avoidance behavior.