The tendency for relative response rate to approach matching as multiple schedule component duration decreases has been interpreted as confirming a prediction of Herrnstein's multiple schedule equation. However, the equation predicts that absolute response rate will decrease in both multiple schedule components as component duration decreases. The absolute response-rate data of two studies of component duration do not support this prediction; absolute rate either increased or remained relatively constant.
Pigeons' choice responding on 10-sec interpolated probes was studied after baseline training on multiple variable-interval variable-interval schedules of food reinforcement. Unreinforced choice following training with three different relative reinforcement rates (Experiment 1), with a 3-ply multiple schedule (Experiment 2), and with three different relative reinforcement durations (Experiment 3) was examined. Least squares lines were fit to choice relative response rate and schedule relative response rate as functions of training relative reinforcement rate; choice slope was significantly greater than schedule slope in all three experiments. This result is counter to the prediction of Herrnstein's (1970) theory that these slopes should not differ. Lues's (l959l theory also failed to account for the data. It was concluded that choice responding was controlled by both approach to the stimulus associated with the smaller mean interreinforcerinterval or the longer duration, and avoidance of the other stimulus.Herrnstein's (1970) theory specifies the relation between response strength and reinforcement rate in the components of multiple and concurrent schedules. Since Herrnstein further proposes that "choice is nothing but behavior set into the context of other behavior" (p. 255), relative response frequency should be the same whether measured simultaneously or successively, once component response strengths are established by the schedule. That is, Herrnstein's equation for multiple-schedule relative response frequency is also the equation for choice relative response frequency following multiple-schedule training. This prediction, that schedule and choice relative rates should be equivalent functions of reinforcement, was evaluated by investigating choice responding on interpolated probes following asymptotic multiple-schedule training.The choice probe results also permit further evaluation of the applicability of Luce's (1959) choice model in extinction tests. Luce (1977) has noted that matching on concurrent schedules is consistent with his model. However, Herrnstein and Loveland (1976), who employed a transfer test similar to that used here, found that choice results were more extreme than predicted by Luce's model. Herrnstein and Loveland (1976) employed this scale in predicting choice. The question of interest here is whether or not the model applies when choice is predicted by a scale derived from previous choice tests, not schedule responding. If the theory applies in this situation, we would have a basis for a ratio scale of relative response strength as a function of relative reinforcement rate for multipleschedule training, which is what the matching law provides for concurrent-schedule training. Nevin (1974) has reviewed arguments for the desirability of such a scale, with response strength conceived as a psychological construct that varies with parameters of reinforcement.Experiment 1 studied choice following three different relative reinforcement rates. To extend the generality of the results and...
Pigeons were studied on multiple variable-ratio yoked-variable-interval schedules in which components had equal rates of food reinforcement and appeared equally often on each of two keys. Interpolated between component changes on the final multiple schedule were lO-sec probes in which both schedule stimuli were present, one on each key. During multiple schedule training, variable-ratio response rates were greater than yoked-variable-interval rates; however, response rate differences in the components were not a function of the mean ratio value for the 40-to-320-ratio range studied. During the choice probes, subjects responded more to the stimulus associated with the interval schedule than to the one associated with the ratio schedule. It was concluded that pigeons prefer interval schedules over equal reinforcement rate ratio schedules, because the former generate fewerresponses per reinforcement.Bloomfield (1967) reported that two of three pigeons on multiple fixed-ratio variable-interval (FR VI) schedules required a higher FR than VI reinforcement rate for the absence of schedule interaction effects. Bloomfield argued that this result was consistent with other data (Appel, 1963), supporting the conclusion that FR schedules have aversive effects that subtract from the positive value of the reinforcer. He then speculated that these results might imply a general preference of pigeons for interval over ratio schedules.Possible alternative interpretations of Bloomfield's results suggest that more direct evidence for a general preference would be of interest. For example, the VI preference in his data is consistent with the finding that aperiodic schedules are preferred over periodic schedules with the same reinforcement rate (Herrnstein, 1964; Killeen, 1968a). Also, Moore and Fantino (1975) have concluded that "pigeons prefer a second schedule to the extent that the response contingencies of the first schedule must be satisfied during discriminable periods of nonreinforcement" (p. 339). Since FR schedules require responding during discriminable periods of nonreinforcement, Moore and Fantino's analysis would imply a preference for the VI schedule in Bloomfield's results. The influence of either of these factors would limit the generality of Bloomfield's conclusion about schedule preference per set The present experiment investigated schedule preference with a method that would not allow these alternative explanations.Equal reinforcement rates were produced for ratio and interval schedules by a within-subject yoking procedure whereby the interval schedule was based on the subject's performance on the ratio schedule. If this multiple variable-ratio yoked-variableinterval (VR y-VI) schedule produced the difference in ratio and interval response rates that is seen in the between-subject yoke (Ferster & Skinner, 1957), then it would be clear that the subjects were discriminating the two schedules. A choice test between the component stimuli may then reveal any schedule preferences. Further, if a functional relation betwe...
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