Are you there or not anymore? An investigation on the effects of social support and the order in which it is received on the development of mechanical hypersensitivity

Social support, such as handholding from a romantic partner, can reduce pain and physiological responses to noxious stimuli. We previously demonstrated that handholding during the induction of secondary mechanical hypersensitivity via electrical stimulation reduces the spatial spread of hypersensitivity. However, real-life social contexts are dynamic, and it remains unclear whether such support has lingering effects after its withdrawal or whether prior support buffers against subsequent absence. In this pre-registered study, we expanded our earlier sample (N=37 couples) with an additional 28 couples (total N=65) to examine the effects of support and condition order on mechanical hypersensitivity. All female participants underwent two sessions (Support and Alone), where involved partner handholding during Middle Frequency Stimulation (MFS) of the volar forearm. We measured the perceived intensity, unpleasantness, and spatial spread of hypersensitivity before and after MFS. Results replicated and extended our earlier finding: support significantly reduced both vertical and horizontal spread of hypersensitivity, regardless of condition order. Subjective ratings of pain intensity and unpleasantness revealed a complex interaction with condition order. Elevated baseline mechanical sensitivity and MFS ratings were observed when support was provided first, while receiving support after having been alone yielded the lowest ratings, consistent with safety signaling or relief effects. The post-MFS increase in ratings was inversely related to baseline sensitivity, resulting in no significant differences. Our findings suggest that while the modulation of hypersensitivity spread by support is robust and order-independent, processes related to expectation and habituation shape subjective reports of hypersensitivity and their modulation by social support.