Slow stroking evokes a more pleasant sensation but similar autonomic nervous system response than rhythmic touching

Abstract

Stimulation of C-tactile afferents with gentle slow stroking of the hairy skin, also called affective touch, evokes a pleasant sensation. We intended to describe psychological and tonic physiological changes evoked by slow stroking, as well as associations between pleasantness of skin sensation and physiological changes and trait-like self-reported characteristics (i.e., the major dimensions of personality and various aspects of body awareness). To shed more light on the factors involved in the effects of slow stroking, stroking (5 cm/sec) for 3 minutes was compared to skin-focused attention and gentle rhythmic touching of the skin. 85 young individuals participated in an experiment. Sensory characteristics of the stimulation (pleasantness, intensity) and physiological changes (HR, HF, RMSSD, respiratory rate, SCL) were assessed during the stimulation periods. The most pleasant and intense skin sensations were reported in the slow stroking condition, followed by the rhythmic touching and attention condition. Slow stroking and rhythmic touching significantly decreased HR and increased HF, RMSSD, respiratory rate, and SCL compared to baseline and the attention condition. Pleasantness of the sensation in the slow stroking condition was largely independent from the evoked physiological changes and from the assessed trait-like characteristics; Bayesian analysis indicated the superiority of null hypothesis (i.e. lack of associations) for almost all cases. Although rhythmic touching is experienced as less pleasant and intense, it has a relaxing (parasympathetic) effect on cardiac activity that is comparable with the effect of slow stroking. Characteristics of the evoked skin sensation are not related to major dimensions of personality and body awareness.