Experimental
economic techniques have been widely used to evaluate human risk
attitudes, but how these measured attitudes relate to overall
individual wealth levels is unclear. Previous noneconomic work has
addressed this uncertainty in animals by asking the following: (i) Do
our close evolutionary relatives share both our risk attitudes and our
degree of economic rationality? And (ii) how does the amount of food or
water one holds (a nonpecuniary form of "wealth") alter risk attitudes
in these choosers? Unfortunately, existing noneconomic studies have
provided conflicting insights from an economic point of view. We
therefore used standard techniques from human experimental economics to
measure monkey risk attitudes for water rewards as a function of blood
osmolality (an objective measure of how much water the subjects
possess). Early in training, monkeys behaved randomly, consistently
violating first-order stochastic dominance and monotonicity. After
training, they behaved like human choosers--technically consistent in
their choices and weakly risk averse (i.e., risk averse or risk neutral
on average)--suggesting that well-trained monkeys can serve as a model
for human choice behavior. As with attitudes about money in humans,
these risk attitudes were strongly wealth dependent; as the animals
became "poorer," risk aversion increased, a finding incompatible with
some models of wealth and risk in human decision making.
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