Effect Of Self-affirmation On Psychological And Physiological Response To Pain

Pain is an unpleasant feeling and emotional experience caused by tissue damage or potential tissue damage.Pain can affect the health and quality of life of individuals,but drug analgesia has dependence,side effects and other deficiencies.Therefore it is necessary to explore the methods of psychological analgesia without dependence and side effects.Self-affirmation is affirming important personal values or traits.Previous studies have shown that self-affirmation can buffer social threat to self and reduce the defensive response to threats.And then buffer the physiological and psychological reactions brought about by social threats.Pain is the body’s protective defense response to harmful stimuli,therefore self-affirmation may also buffer the psychological and physiological responses to pain.Pain can be divided into two types:phasic pain and tonic pain,therefore the present study examined the regulatory effect of self-affirmation on these two types of pain.In experiment 1,74 college students were recruited and randomly assigned to self-affirmation group(N = 37,average age 22.19 ± 0.35 years old,18 female students)and control group(N = 37,average age 21.35 ± 0.34 years old,20 female students).In this experiment,the contact heat evoked potential stimulator was used to induce the phasic pain of the subjects.Subjects’ thermal pain thresholds and tolerance thresholds were measured before and after the self-affirmation manipulation.After experimental manipulation,subjects were given thermal stimulation at 49℃ to induce pain potential and assess pain intensity.The results showed that 1)Before self-affirmation manipulation the thermal pain threshold and tolerance thresholds of the two groups were not significantly different.But after self-affirmation manipulation,the thermal pain threshold and tolerance thresholds of the self-affirmation group were significantly higher than the control group.2)the self-affirmation group had significantly lower pain intensity score and P2 amplitude than the control group.3)the pain intensity scores of the subjects were significantly positively correlated with P2 amplitude.These results suggest that self-affirmation buffer the individual’s psychological and physical responses to phasic pain.Experiment 2 recruited 40 university students(average age 19.00 ± 1.50 years old,20 female students).The tonic pain was induced by the Cold Pressor Test(8.92 ±0.05℃,3 minutes).The baseline test was followed by self-affirming manipulation and then the Cold Pressor Test.Psychological and physiological activity was measured in 4 period: baseline,self-affirmation manipulation(self-affirmation condition/control condition),the cold pressor presentation and fading period.The results found that the psychological indicators(pain intensity and unpleasantness score)and EEG indicators(Theta,Beta and Gamma power)of the subjects in the presentation period were significantly higher than those in the baseline and the fading period,while the ECG indicators(LF/HF)in the presentation period were significantly lower in the baseline period.These results suggest that the Cold Pressor Test evoked the individual’s pain perception and physiological stress response.However,no significant main effects of self-affirmation or related interactions were found for the above indicators.It suggests that self-affirmation does not modulate psychological and physiological responses to tonic pain.Further analysis of the data in the presentation period found that subjects with high levels of state anxiety had significantly higher heart rate variability indicators(RMSSD,LF-HRV,and HF-HRV)in the self-affirmation condition than in the control condition,However,no significant differences were found in these indicators among subjects with low state anxiety levels.This suggests that self-affirmation reduces physiological stress responses during pain in subjects with high levels of state anxiety.To sum up,self-affirmation has a significant analgesic effect on phasic pain.The impact of self-affirmation on the psychological and physiological responses to tonic pain was not found.