A method for determining the relationship between food consumption and the price of food (demand function) in behavioral economic experiments is described. Although previous methods have generally required as long as 40 days, the present method can generate a complete demand function within 7 days, and therefore may be more suitable for use in the evaluation of drugs, toxins, and physiological/anatomical interventions. Moreover, measures of circadian rhythmicity, postreinforcement pause durations, and interresponse times can also be generated. Three experiments tested the stability of the method in a variety of procedural manipulations: repeated exposure to the procedure, increasing versus random daily food price, and size of daily changes in food price. The procedure generated demand functions that were similar to those that require more extended testing, and the demand functions were not generally affected by procedural manipulations. Body weight, which can also affect consumption, generally decreases with increases in the price of food; so this variable should be recorded and used as a covariate in analyzing demand functions. With the exception of circadian rhythmicity, the other measures were stable across procedural variations and showed expected changes as a function of food price: postreinforcement pause durations increased as price increased, but interresponse times did not.Recently a great deal of interest has focused on the application of economic principles to the analysis of behavioral data generated by animal subjects (Allison, 1983;Hursh, 1980Hursh, , 1984. A primary task for such an analysis is the generation of a function that relates the price of a commodity (e.g., the number of responses required to obtain a 45-mg food pellet) to the quantity of the commodity that is consumed. Functions that relate quantity consumed to price are known in economics as demand curves, and Figure 1 illustrates the features of demand curves that are commonly seen in the behavioral literature. Assume that the subjects earn all of their food within the experimental apparatus by performing a specified response, and that the delivery of food pellets is contingent upon production of a fixed number of responses (i.e., a fixed ratio, or FR, schedule of reinforcement). Price (P), then, is measured in responses per pellet, as indicated along the abscissa of Figure 1. The quantity consumed (Q), measured in pellets of food, is plotted on the ordinate. Note that the ordinate and abscissa are both logarithmic. A demand curve, such as A in Figure 1, is generated by changing the price of the commodity and measuring the quantity of the commodity that is then consumed. Demand elasticity is defined as the percentage change in consump- tion per percentage change in price (%i1Q/%M7). In double logarithmic plots, the slope of the demand curve can be directly read as elasticity. Unit elasticity is depicted in curve B, since a 1% change in price produces a 1% change in consumption (i.e., slope = -1). Inelastic demand is illustrated in cur...