The disjunction effect and reason-based choice in games

This paper reports an experiment that extends previous findings of the disj unction effect, sometimes described as a violation of Savage's sure-thing p rinciple. Evidence of the disjunction effect is observed using elicited bel iefs about others' actions (rather than controlled beliefs) in a prisoners' dilemma studied by Shafir and Tversky (1992) as well as in an asymmetric v ersion of it and in a nondilemma game with a unique equilibrium. Debiasing techniques as well as implications for these extensions are discussed. (C) 1999 Academic Press.