Experimentally manipulating perceptions regarding acupuncture elicits different responses to the identical acupuncture stimulation

Excessive expectancy or an aversion to acupuncture makes it difficult to evaluate the efficacy of acupuncture during clinical trials. We investigated whether experimental manipulations of the perception of acupuncture could elicit different responses to identical acupuncture stimulation. Seventeen participants were assessed with the acupuncture belief scale (ABS) and by measuring tactile and pain sensitivity. Identical acupuncture-related pictures and either positive (positive group; n = 9) or negative (negative group, n = 8) statements related to treatment were presented, and participants used the self-assessment manikin (SAM) to rate each acupuncture-related image. Participants were stimulated with the same intensity for 5 min and then evaluated for acupuncture-induced, self-reported pain. Heart rate variability (HRV) was measured before and after the acupuncture stimulation. Participants in the negative group were less valenced and more aroused in response to the same acupuncture picture compared to those in the positive group. Negative cognition regarding acupuncture modality resulted in a change of the relationship between the pre-experimental expectancy of acupuncture and self-reported pain. The negative group produced an increased low-frequency component of HRV after acupuncture, whereas the positive group did not. Subjective and sympathetic responses to acupuncture can be modified by perception. Our findings may help to understand the psychological factors related to acupuncture modality.