Changes in sympathetic tone during cooperative game play

We investigated the relationship between stress (specifically, sympathetic tone) and effective and efficient cooperation between partners using a cooperative version of a Tetris game as a model of limited resources in a shared environment. Participants were recruited from 2 distinct sociocultural orientations: individualism (Americans) and collectivism (Japanese). We compared the frequency domain of heart rate variability (HRV) and average scores on the short form of the Positive and Negative Affect Scale (I-PANAS-SF) for individuals and dyad partners. Japanese players cooperated more effectively and their scores on the positive subscale of the I-PANAS-SF for both self and partner were higher than those of American players. However, Japanese participants experienced more stress, as indicated by an increased low-to-high HRV frequency ratio. Our results suggest that sociocultural orientation affects the motivation to promote prosocial interactions that result in efficiency and effectiveness of cooperation.