Heart Rate Measurement and the Correlation of Indices of Arousal

Twenty-two subjects watched a stressor motion picture film, "Subincision," which was expected to stimulate autonomic arousal, and 22 control subjects saw a benign film, "The Corn Farmer." Heart rate and skin conductance were recorded. When analyzed by previously used methods, skin conductance changes over time showed a close correspondence to film content, while heart rate did not. A new method of sampling heart rate records, the method of mean cyclic maxima, gave results closely paralleling those of skin conductance. This method appears to be a major improvement over previous approaches to heart-rate measurement in that it produces greater correspondence to both skin conductance and to the known characteristics of the motion picture stimulus. Since an earlier study showed that phenomenological ratings of emotional reaction closely followed a similar curve of skin conductance, it is expected that future studies will show heart rate variation and phenomenological ratings also to be closely related.