Individual differences in the cardiac component of the orienting response
Mylan, Marci M.
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Forty-two male subjects participated in two separate experimental sessions spaced at seven day intervals. The subjects were given the Locus of Control scale. During each session, the subjects viewed multiple presentations of two types of novel stimuli. Heart rate was monitored during a total of forty presentations of four stimulus groups, and for five seconds prior to every stimulus onset. The trials of interest in this experiment were trials one and nine of every stimulus group. Trial one represented orienting/ reorienting trials. Trial nine represented habituation trials. The results indicated that the initial novel stimulus of each group did elicit a decelerative heart rate orienting response. The heart rate response had habituated by the ninth trial of a stimulus set. However, stable individual differences in the cardiac component were not found. The findings of this study also indicated that subjects scoring within the external range of the Locus of Control scale manifested larger heart rate decreases during novel stimuli than did subjects scoring within the internal range of the Locus of Control scale. These findings indicate that heart rate deceleration as a response to novel stimuli may not be a stable individual characteristic over time.