[Effects competition and cooperation between two participants on a third one's heart rate, problem solving, and cognitive responses in triad].

Forty-two women's junior college students, healthy and aged 19 to 20 years, were divided into two (competitive or cooperative) groups, each consisting of seven triads. A problem solving task was given to each triad with two ("paired") participants instructed to be either competitive or cooperative. Mean heart rate during problem solving increased in both groups, but the degree of the heart rate increment showed significant differences as a function of group condition and position within triad. The heart rate of competitive participants increased more than the third ("isolated") one, while that of cooperative participants increased less. Analyses of the task performance and cognitive responses suggested that hyperarousal was induced in the isolated participant under the cooperative situation.