Steady‐state choice between four alternatives obeys the constant‐ratio rule

Abstract

We investigated why violations to the constant-ratio rule, an assumption of the generalized matching law, occur in procedures that arrange frequent changes to reinforcer ratios. Our investigation produced steady-state data and compared them with data from equivalent, frequently changing procedures. Six pigeons responded in a four-alternative concurrent-schedule experiment with an arranged reinforcer-rate ratio of 27:9:3:1. The same four variable-interval schedules were used in every condition, for 50 sessions, and the physical location of each schedule was changed across conditions. The experiment was a steady-state version of a frequently changing procedure in which the locations of four VI schedules were changed every 10 reinforcers. We found that subjects' responding was consistent with the constant-ratio rule in the steady-state procedure. Additionally, local analyses showed that preference after reinforcement was towards the alternative that was likely to produce the next reinforcer, instead of being towards the just-reinforced alternative as in frequently changing procedures. This suggests that the effect of a reinforcer on preference is fundamentally different in rapidly changing and steady-state environments. Comparing this finding to the existing literature suggests that choice is more influenced by reinforcer-generated signals when the reinforcement contingencies often change.

Choice among two and three alternatives

“…The present experiment found no convincing evidence that the birds showed preference pulses in any of the two‐ or three‐alternative conditions; the birds tended not to stay on the just reinforced key. This finding supports Bensemann et al’s () study, which also found no strong evidence for preference pulses. The birds’ preference in the present experiment following a reinforcer was nearly always for the richest alternative.…”

“…Yet, Jensen's model was able to mathematically describe all of the birds’ data equally well, would it be possible for one model to conceptually describe contradictory data like this? Would the same model conceptually consolidate the findings of Davison et al (), Elliffe and Davison (), and Bensemann et al (), as well as the contradictory findings of the present experiment, and the findings of Beeby and Alsop ()? Mathematically, Jensen's model is a step towards “completing” the GML, but conceptually it is difficult to see how one model could untangle the variety of results from multiple‐alternative choice experiments.…”

“…Beeby and Alsop () produced different findings to Davison et al (), Elliffe and Davison (), and Bensemann et al (). They trained six pigeons on a three‐key concurrent schedule with a constant reinforcer ratio of 9:3:1 across the alternatives and a 2‐s changeover delay (COD).…”

“…Both Davison et al and Elliffe and Davison used a rapidly‐changing‐alternatives method with four alternatives, whereas the present experiment and Beeby and Alsop () kept the reinforcer ratios in the same positions within conditions and there were only three alternatives. Bensemann et al () replicated Elliffe and Davison but did not use rapidly‐changing‐alternatives . Bensemann et al did not find any consistent differences between different response ratio pairs with the same relative reinforcer rate.…”

“…Bensemann, Lobb, Podlesnik, and Elliffe () tried to replicate the findings of Davison et al () and Elliffe and Davison () but without arranging a rapidly‐ changing‐alternatives procedure. Instead, they kept the schedules associated with each of the four alternatives constant within each condition and different arrangements of the schedules were organized across eight conditions, each lasting 50 sessions.…”