[Trust and cooperation: a comparison of in-group preference and trust behavior between American and Japanese students].

American and Japanese students, 44 and 38, respectively, participated in an experiment, and played a game together in seven- or eight-person groups. The game was a repeated version of bilateral trust game: Prisoner's Dilemma (PD) with choice of dependence. In no-information condition, participants were not told that some of the group members were from another country. In information condition, they were told that about half of the members were Japanese and the rest were Americans. We examined whether or not people trusted ingroup members (those from the same country) more than outgroup members, and whether or not they cooperated with ingroup members more than outgroup members. We found no evidence of ingroup bias in terms of trust and cooperation, and we did not find significant differences in the levels of trust or cooperation between those found among Americans and those among Japanese. On the other hand, it was found that American participants were more sensitive than Japanese counterparts, to information regarding the past trust behavior of other players when they were deciding whom they trust and whether or not they reciprocate another's trust.