Adaptive learning and punishment are highly prominent competing explanations for ultimatum game behavior. We report on an experiment that considers each theory in stand-alone form, so that one does not rely on the other in any substantial way. Our data exhibits patterns for which punishment can...

Video taped group decision experiments on a two-person investment game were used to elicit the motivational structure of subjects' behavior. A majority of investors trusted (invested) and a majority of receivers reciprocated (returned). Cognition and decision were focused on extremes: total or...