Abstract
People prefer unambiguity to ambiguity in decision making under ambiguity. This phenomenon, known as “ambiguity aversion,” is thought to be influenced by environmental and psychological factors. The present research demonstrated the effects of choice opportunity (the availability of choice of cards), competition (the presence vs. absence of a competitor), and stimulus familiarity (familiar playing cards vs. unfamiliar tarot cards) on choice of ambiguity. Participants preferred the ambiguous deck of cards when they were allowed to choose playing cards. In the tarot-card task, however, they did not show a preference for the ambiguous deck even if they could choose the cards by themselves. The competition factor had no effect on the participants' choice. These findings indicate that choice opportunity and stimulus familiarity affect decision making under ambiguity.
