Receiving Two Consequences: Tests of Monotonicity and Scale Invariance

The present study investigated two behavioral properties of decision making. Participants were presented two alternatives, each of which yielded two consequences jointly (joint receipt, JR). Monotonicity of JR states that choices remain invariant when the same lottery is adjoined to both of the original alternatives. The data failed to reject monotonicity of JR. Scale invariance states that choices remain invariant under proportionate (scale) changes of the lottery consequences. This property was not rejected for three of four classes of JR lotteries having a common consequence, but it was rejected for two of three classes of binary lotteries and for two of the four classes of general JR lotteries. We conclude that scale invariance does not hold in general. The implication of these findings for utility theory, testing its fundamental assumptions, and determining the functional form of utility is discussed. Copyright 2000 Academic Press.