MacDonall James S
Department of Psychology, Fordham University, Bronx, New York 10458, USA.
J Exp Anal Behav. 2003 Mar;79(2):219-32. doi: 10.1901/jeab.2003.79-219.
Performance on concurrent schedules can be decomposed to run lengths (the number of responses before switching alternatives), or visit durations (time at an alternative before switching alternatives), that are a function of the ratio of the rates of reinforcement for staying and switching. From this analysis, a model of concurrent performance was developed and examined in two experiments. The first exposed rats to variable-interval schedules for staying and for switching, which included a changeover delay for reinforcers following a switch. With the changeover delay, run lengths and visit durations were functions of the ratios of the rates of reinforcement for staying and for switching, as found by previous research not using a changeover delay. The second directly assessed the effect of a changeover delay on run lengths and visit durations. Each component of a multiple schedule consisted of equivalent stay and switch schedules but only one component included a changeover delay. Run lengths and visit durations were longer when a changeover delay was used. Because visit duration is the reciprocal of changeover rate, these results are consistent with the established finding that a changeover delay reduces the frequency of switching. Together these results support the local model of concurrent performance as an alternative to the generalized matching law as a model of concurrent performance. The local model may be preferred when accounting for more molecular aspects of concurrent performance.
在并发程序安排下的表现可以分解为运行长度（切换选择之前的反应次数）或停留时间（切换选择之前在某一选择上停留的时间），它们是停留和切换强化率之比的函数。基于此分析，我们开发了一个并发表现模型，并在两个实验中进行了检验。第一个实验让大鼠接触用于停留和切换的可变间隔程序安排，其中包括切换后强化物的转换延迟。有了转换延迟，运行长度和停留时间就是停留和切换强化率之比的函数，这与之前未使用转换延迟的研究所发现的结果一致。第二个实验直接评估了转换延迟对运行长度和停留时间的影响。多重程序安排的每个组成部分都由等效的停留和切换程序组成，但只有一个组成部分包含转换延迟。使用转换延迟时，运行长度和停留时间更长。由于停留时间是转换率的倒数，这些结果与已有的发现一致，即转换延迟会降低切换频率。这些结果共同支持了并发表现的局部模型，可作为并发表现模型的广义匹配法则的替代。在解释并发表现的更多分子层面时，局部模型可能更受青睐。
