 Rudolf Groner analyzed the history of heuristics from its roots in ancient Greece up to contemporary work in cognitive psychology and artificial intelligence, proposing a cognitive style "heuristic versus algorithmic thinking" which can be assessed by means of a validated questionnaire.Gerd Gigerenzer and his research group argued that models of heuristics need to be formal to allow for predictions of behavior that can be tested.They study the fast and frugal heuristics in the "adaptive toolbox" of individuals or institutions, and the ecological rationality of these heuristics, that is, the conditions under which a given heuristic is likely to be successful.