Following a baseline session, human subjects were allowed to choose between concurrently available games contingent upon a fixed amount of bar pressing. It was assumed that the total amount of a dimension apportioned to bar pressing and game playing is conserved between baseline and contingency sessions. Conservation theory was shown to be moderately successful in predicting game choices. The results are also discussed in terms of economic demand theory. Elasticity of demand (defined in operant terms as the ratio of the percentage change in contingent responding per session relative to the percentage change in the instrumental response requirement) is considered as a function of the degree of substitutability of the contingent responses (games). These economic variables are discussed in relation to psychological choice behavior
