The idea that cooperative groups out-compete less cooperative groups has been proposed as a theoretical possibility for the evolution of cooperation through cultural group selection. Previous studies have found an association between increased cooperation and exposure to inter-group violence, but most have not been able to identify the specific target of cooperation and are based on correlation...

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Research accomplishment of Professor Kyosuke Tsuda was summarized and published as “A list of publications by Professor Kyosuke Tsuda and his collaborators” at his retirement from University of Tokyo at the age of 60. His memoir and treatise by his collaborators were published. In addition, the journal Heterocycles published as a commemorative issue for his 75 birthday, in which appeared at the...

Economic games such as the Ultimatum Game (UG) and Prisoner's Dilemma (PD) are widely used paradigms for studying fairness and cooperation. Monetary versions of these games involve two players splitting an arbitrary sum of money. In real life, however, people's propensity to engage in cooperative behavior depends on their effort and contribution; factors that are well known to affect perception...

Older adults have been shown to avoid negative and prefer positive information to a higher extent than younger adults. This positivity bias influences their information processing as well as decision-making. We investigate age-related positivity bias in charitable giving in two studies. In Study 1 we examine motivational factors in monetary donations, while Study 2 focuses on the emotional effe...