Cardiovascular changes during social competition in a mixed-motive game.

Male and female subjects played a mixed-motive game against a male confederate under either a 20% cooperative or an 80% cooperative strategy while cardiovascular responses were computer monitored. Females had larger heart rate responses than males during play against the competitive strategy, and the opposite was true during play against the cooperative strategy. Subjects who were more competitive during the game or who scored higher on a coronary-prone (Type A) behavior scale or who reported having an action orientation toward life stress tended to have larger heart rate responses during the game than the remaining subjects. The results draw attention to the importance of covert autonomic responses for understanding overt behavioral choices in mixed-motive games and to the potential utility of this behavioral model for studying the role of psychosocial factors in psychosomatic illnesses.