The stay/switch model of concurrent choice

Abstract

This experiment compared descriptions of concurrent choice by the stay/switch model, which says choice is a function of the reinforcers obtained for staying at and for switching from each alternative, and the generalized matching law, which says choice is a function of the total reinforcers obtained at each alternative. For the stay/switch model two schedules operate when at each alternative. One arranges reinforcers for staying there and the other arranges reinforcers for switching from there. Rats were exposed to eight or nine conditions that differed in the arrangement of the values of the stay and switch schedules. The generalized matching law described preferences when arrangements were similar to those found when using two concurrently running interval schedules. It did not, however, describe all preferences when using different arrangements. The stay/switch model described all preferences in one analysis. In addition, comparisons of selected conditions indicated that changing the ratio of obtained reinforcers was neither necessary nor sufficient for changing preference as measured by response ratios. Taken together these results provide support for the stay/switch model as a viable alternative to the generalized matching law and that the critical independent variable is allocation of stay and switch reinforcers.

Fig 1

The logs of the ratios of stay responses plotted as a joint function of the logs of the ratios of the sums of the stay and switch reinforcers obtained per visit and the logs of the ratios of the ratios of the stay and switch reinforcers obtained per visit. The plane shows the best-fitting plane, using the stay/switch model (Equation 3) and data from all conditions.

Fig 2

The logs of the ratios of times plotted as a joint function of the logs of the ratios of the sums of the stay and switch reinforcers obtained per visit and the logs of the ratios of the ratios of the stay and switch reinforcers obtained per visit. The plane shows the best-fitting plane, using the stay/switch model (Equation 3) and data from all conditions.

Fig 3

The logs of the ratios of responses plotted as a function of the logs of the ratios of obtained reinforcers. The solid line shows the best-fitting line, using the generalized matching law (Equation 5) and data from symmetrical conditions. The horizontal and vertical range bars show the range of the reinforcer ratios and the response ratios, respectively, during the 5 days of stable responding.

Fig 4

The logs of the ratios of times plotted as a function of the logs of the ratios of obtained reinforcers. The solid line shows the best-fitting line, using the generalized matching law (Equation 5) and data from symmetrical conditions. The horizontal and vertical range bars show the range of the reinforcer ratios and the time ratios, respectively, during the 5 days of stable responding.

Fig 5

The predicted (stay) response ratio plotted as a function of the obtained (stay) response ratio using the generalized matching law (GML, Equation 5) and the stay/switch model (S/S, Equation 3). The r² for descriptions by the generalized matching law is in the upper left-hand corner of each plot. The r² for descriptions by the stay-switch model is in the lower right-hand corner of each plot. The best-fitting line to the data using the stay/switch model is solid. The best-fitting line to the data using generalized matching law is dashed. The dotted line is the locus of perfect prediction.