Scientists have long known that happily married couples tend to be healthier and live longer than people who aren’t in a long-term relationship. An interesting experiment recently provided some insight into why that’s true.

Psychologists from the University of Wisconsin and the University of Virginia recruited sixteen couples who were considered happily married based on their own assessment and an indepth interview. The women were placed in an M-R-I, an imaging device that provided detailed views of the regions of their brains that register physical and emotional alarm.

For some, being cooped up in the narrow confines of an M-R-I was enough to provoke anxiety and apprehension. On top of that, the women were periodically subjected to a mild electric shock to the ankle.

Scans of the women’s brains pinpointed the source of these anxious feelings, showing peaks of activity in the areas involved in anticipating pain and regulating negative emotions.

But that all changed when the women’s husbands reached inside the machine to grasp their wife’s hand. The brain activity levels that reflected a perceived threat immediately plummeted. Even a stranger’s hand, offered in support, made the levels go down, though not as dramatically.

This experiment is considered the first to show how human touch affects the neurological response to threatening situations. It also provides intriguing evidence of how a loving relationship can protect an individual from a host of negative health consequences believed to result from stressful situations.