Yamagishi et al. (2014)

Yamagishi, T. (山岸俊男)Yang Li, Y. (李楊), Takagishi, H. (高岸治人), Matsumoto, Y. (松本良恵), & Kiyonari, T. (清成透子)  (2014).
In Search of Homo economicus.
Psychological Science, 5(9), 1699-1711.
doi: 10.1177/0956797614538065
Homo economicus, a model for humans in neoclassical economics, is a rational maximizer of self-interest. However, many social scientists regard such a person as a mere imaginary creature. We found that 31 of 446 residents of relatively wealthy Tokyo suburbs met the behavioral definition of Homo economicus. In several rounds of economic games, participants whose behavior was consistent with this model always apportioned the money endowed by the experimenter to themselves, leaving no share for their partners. These participants had high IQs and a deliberative decision style. An additional 39 participants showed a similar disregard for other people’s welfare, although they were slightly more altruistic than those in the Homo economicus group. The psychological composition of these quasi–Homo economicus participants was distinct from that of participants in the Homo economicus group. Although participants in the latter group behaved selfishly on the basis of rational calculations, those in the former group made selfish choices impulsively. The implications of these findings concerning the two types of extreme noncooperators are discussed.