To determine how the brain processes physical touch, researchers used a soft bristled brush to caress participants’ arms at either a quick or a slow pace. MRI scans of participants’ brains revealed activity in the insula, a region of the brain associated with emotional responses, during the slow, sensual strokes. Brain activity was similar when participants watched someone else receive slow strokes, but not when touch was directed toward inanimate objects.
Morrison, I., Björnsdotter, M., & Olausson, H. (2011). Vicarious responses to social touch in posterior insular cortex are tuned to pleasant caressing speeds. The Journal of Neuroscience, 31(26), 9554–9562.