Figure 2.

Ambiguity aversion in monkeys. (A) Behavioral preference for risky over ambiguous options. Dots represent frequency of choosing risky option for each of the 100 individual risky probabilities on risky vs. ambiguous trials. Line is a best-fit cumulative Gaussian. The point of subjective equivalence (PSE, shown by vertical gray dashed line) indicates values at which subjects were indifferent to the two options. The PSE is smaller than 50, indicating that monkeys were ambiguity-averse. (B) Individually, all four monkeys showed ambiguity aversion (PSE significantly less than 50). (C) Ambiguity aversion varied parametrically with degree of ambiguity. Greatest aversion was observed for high uncertainty options.