Abstract
Behavior change by persuasive communications in a social dilemma, in which a university tried to persuade students to park their motorcycles in a designated lot in order to resolve noise problems, was studied by a questionnaire. Hayashi's quantification theory III was applied to variables such as subjective norms, beliefs in the effectiveness of one's cooperation, the perception of campus traffic conditions and attitudes toward one's parking behavior. Factor scores obtained were subjected to a cluster analysis, which, within 105 defectors, yielded three subgroups. Contrary to prediction, subgroups were not different in their cooperation ratio examined 10 months later, but tended to be different in their readiness for acceptance of persuasion and in their intention to cooperate in a social dilemma other than parking. Two mechanisms underlying cooperation were revealed: internalization of prosocial norm, and compliance in which cooperation was unaccompanied by correspondent changes in normative beliefs. The Fishbein model was applicable only to change through internalization. A linear assumption in the Fishbein model between evaluative attitude and behavior should be reexamined in its application to a social dilemma.
