Preference Reversals Under Ambiguity

Preference reversals have been widely studied using risky or riskless gambles. However, little is known about preference reversals under ambiguity (unknown probabilities). Subjects were asked to make a binary choice between ambiguous P-bets (big likelihood of giving small prize) and ambiguous $-bets (small likelihood of giving large prize) and their willingness to accept was elicited. Subjects then performed the same two tasks with risky bets, where the probability of winning for a given risky bet is the center of the probability interval of the corresponding ambiguous bet. Preference reversals are not only replicated under ambiguity but are even stronger than are those under risk. This is due to higher elicited prices for the $-bet and lower elicited prices for the P-bet under ambiguity than under risk. This result can be explained by the shape of the weighting function for different levels of uncertainty and for different elicitation modes. <i>This paper was accepted by Peter Wakker, decision analysis.</i>