It has long been established anecdotally that MDMA enhances social behaviour and this has been tested more frequently in experimental settings recently. To determine whether MDMA affected the perceived pleasantness of touch, Bershad et al. gave healthy individuals a high (1.5 mg/kg) or low (0.75 mg/kg) dose of MDMA, Methamphetamine (20mg) or placebo, in a double blind within-subjects design study. Participants then rated the pleasantness of CT-optimal (slow gentle) vs non-CT-optimal (fast abrasive) stroking whilst simultaneously having activity from their Zygomaticus (smile) and Corrugator (frown) muscles recorded. While CT-optimal touch is typically rated as the most pleasant, it was found that MDMA significantly increased the perceived pleasantness of this slow touch, but not the fast touch. Zygomatic (smile) activity was also greatly increased in the MDMA condition compared to control. Furthermore, these increases in pleasantness/positive affect was specific to the higher dose of MDMA and was not present for the methamphetamine manipulation. This suggests that MDMA does indeed impact social behaviour increasing the subjective (and outward expression) of pleasantness for affective touch.
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