More and more researchers are paying attention to the importance of creating and enhancing communities that facilitate goods consumption in companies' marketing activities. Although many previous researches proved that interactions between members of communities contribute to facilitating goods consumption, the reason as to why determinants for such communities vary between social and psychological communities has not yet been revealed. This research hypothesized that in a social community, a sense of community is generated from reciprocal expectation cue supported by the hypothesis of bounded generalized reciprocity, and in a psychological community, it is generated from outgroup threats cue supported by the social identity theory, then I investigated these hypotheses by an empirical study. The results showed, with limitations, that characteristics of communities differentiate the generating processes of a sense of community.

Network theory is known as one of the major theories that can explain consumer memory. Some previous studies based on the theory have found that the presence of competing ads has negative effects on consumer memory for a focal ad, but other previous research has found that it has positive effects. This study aims to extend network theory so that it can explain positive effects as well as negative effects. Specifically, we improve the theory by focusing on ease of memory tasks. Then, we propose and test two hypotheses that identify conditions under which these effects can appear.