Physiological and behavioral differentiation between pain and anxiety

Twenty-seven subjects were divided Into High and Low anxiety groups on the basis of their scores on the Taylor Manifest Anxiety Scale. Physiological responses and a behavioral response were measured while under the induced arousal states of anxiety and pain. The physiological responses measured were systolic and diastolic blood pressure, respiration, heart rate, and galvanic skin response. The behavioral measure was the determination of the critical flicker fusion threshold. Anxiety was aroused by leading the subjects to believe that they were about to receive an injection of an oral anesthetic and pain was induced by electrically stimulating the central incisor. The results of the study were examined to test the following hypotheses; 1) There is some distinguishable pattern of physiological responses related to the arousal states of anxiety and pain that allows differentiation between the two states; 2) There is some distinguishable pattern of behavioral effects associated with anxiety and pain that allows differentiation between the two arousal states. The results of this study were as follows: (1) Differences between the High and Low Anxiety groups. No differences between the two groups were found when the physiological responses were compared. The descending critical flicker fusion threshold during the arousal state of pain was significantly higher for the Low Anxiety group. (2) Physiological responses during anxiety and pain. Both the conditions of anxiety and pain Increased the physiological responses of the Ss. Significant increases were found in systolic blood pressure, respiration, and galvanic skin responses during anxiety and pain. Diastolic blood pressure and heart rate showed significant increases only during anxiety. Significant differences between the anxiety and pain conditions were found for increased systolic blood pressure and heart rate during anxiety. (3) Behavioral responses. Pain and anxiety significantly decreased the ascending and descending critical flicker fusion thresholds. Anxiety decreased both the ascending and descending threshold to a greater extent than pain. (4) Physiological and behavioral responses correlated. Small insignificant correlations were found among the physiological measures. However, blood pressure, especially diastolic, was significantly correlated with critical flicker fusion. The correlations were greatest for diastolic blood pressure and descending flicker fusion during the experiencing of pain. Those subjects who ranked high on one physiological measure under one condition were found to rank high on that measure under another condition. Also, those subjects who ranked high in autonomic activity were found to rank high for the threshold of visual acuity. The present physiological findings were discussed in light of Funkenstein's theory of epinephrine-like and norepinephrine-like responses (Funkenstein et al. 1957). The findings do not appear consistent with the findings of Funkenstein and are interpreted in terms of a mixed model of epinephrine and norepinephrine-like responses (Martin, 1961). The failure to find any differences In physiological responses of the High and Low Anxiety groups was discussed in terms of Spielberger's hypothesis of 'ego stress' vs. situational stress (Spielberger, 1966). The possibility of the relationship between the diastolic blood pressure and the critical flicker fusion was discussed with respect to the hypothesis of Landis, (1951). The increased blood flow to the cerebral cortex during anxiety and pain as represented by the increased systolic and diastolic blood pressure is postulated as the cause of the increased visual acuity. The greater the blood pressure during anxiety the greater was the sensitivity of the subject to the flicker.Psychology, Department o