ABSTRACT
As many of the chapters in this volume illustrate, a host of procedures have been used to study choice between delayed reinforcers. One dimension that helps to distinguish among the different procedures is the duration of the choice period. The concurrent-chain procedure (see Davison, this volume; Fantino, Abarca, & Dunn, this volume) typically involves an extended choice period in which many responses may be emitted. At the other extreme are procedures with very brief choice periods, in which each trial includes only a single-choice response (Eisenberger & Masterson, this volume). Both types of procedure have their strengths and weaknesses. A major advantage of multiple-response procedures is that they usually produce gradations of choice proportions that provide information about the degree of preference for one alternative over another. In contrast, choice proportions are less informative in single-response procedures, because subjects often show near-exclusive preference for one alternative or the other. To the extent that near-exclusive preference is observed in a single-response procedure, this procedure can indicate which alternative is preferred but not how strongly it is preferred.
