Expectations predict the psychological but not the physiological effects of slow stroking

Response expectancies are expectations referring to changes in voluntarily not controllable internal states, such as mood, body sensations, and peripheral physiology. The current study investigated whether response expectancies can predict experiential and actual and perceived physiological responses to slow stroking of the hairy skin, also called affective touch. 94 young individuals participated in the preregistered within-subject experiment. Participants' mood state and spontaneous expectations with respect to pleasantness of the skin sensation, change in mood state, heart rate, respiratory rate, and skin temperature were assessed before (1) paying attention to the skin, and receiving (2) fast (30 cm/sec) and (3) slow (3-4 cm/sec) stroking for two minutes in a randomized order. Experienced skin sensation, mood state, and perceived physiological changes were measured after the stimulation sessions; actual physiological changes were recorded throughout the experiment. Expectations predicted pleasantness of skin sensation, changes of mood state, and perceived changes for all three physiological modalities in the slow stroking condition. However, expected and perceived physiological changes were unrelated to actual changes. Pleasantness of skin sensation showed a positive association with improvement in mood state. In conclusion, response expectancies can predict experiential changes but not actual physiological changes evoked by slow stroking.