In the study published in the journal Psychophysiology, 102 participants were asked to perform a strenuous task – to dip one foot into three inches of cold water at 3.3 to 4.4 degrees Celsius. University of Arizona researchers measured participants' blood pressure, heart rate, and heart rate variability before, during, and after the task.
The participants, all of whom were in love affairs, were randomly assigned to one of three conditions when completing the task. They either sat in the room with their important partner during the assignment, they were instructed to think about their romantic partner during the task, or they were asked to think about the day during the task.
Those who physically had their partner in the room or thought of their partner had a lower blood pressure response to the cold water stress than the participants who needed to think about their day.
Heart rate and heart rate variability do not vary between the three groups, researchers said. The effect on the blood pressure reactivity was equally strong, whether the partner was physically present or only mentally summoned.