In addition to these correlational studies, several experimental studies have shown that a romantic partner can be a source of distress regulation and emotional equanimity. For example, Coan, Schaefer, and Davidson (2006) examined brain responses (via fMRI) of married women who underwent a laboratory stressor (the threat of electric shock) while each one was holding her husband's hand, holding the hand of an unfamiliar male experimenter, or holding no hand at all. Holding a spouse's hand reduced activation in brain regions associated with stress and distress (i.e., the right anterior insula, superior frontal gyrus, and hypothalamus). The stress-reducing effects of hand holding were greater for women who were more satisfied with their marriages, probably because of the stronger sense of security induced by physical contact with a responsive and supportive husband. In another study, Master et al. (2009) found that holding the hand of a romantic partner reduced perceptions of pain in response to heat stimuli.