Kyonka Elizabeth G E, Grace Randolph C
University of Canterbury, Department of Psychology, Christchurch, New Zealand.
J Exp Anal Behav. 2008 Jan;89(1):49-69. doi: 10.1901/jeab.2008.89-49.
Pigeons responded in a concurrent-chains procedure in which terminal-link reinforcer variables were changed unpredictably across sessions. In Experiment 1, the terminal-link schedules were fixed-interval (FI) 8 s and FI 16 s, and the reinforcer magnitudes were 2 s and 4 s. In Experiment 2 the probability of reinforcement (100% or 50%) was varied with immediacy and magnitude. Multiple-regression analyses showed that pigeons' initial-link response allocation was determined by current-session reinforcer variables, similar to previous studies which have varied only immediacy (Grace, Bragason, & McLean, 2003). Sensitivity coefficients were positive and statistically significant for all reinforcer variables in both experiments. Analyses of responding within individual sessions showed that final levels of preference for dominated sessions, in which all reinforcer variables favored the same terminal link, were more extreme than for tradeoff sessions in which at least one reinforcer variable favored each alternative. This result implies that response allocation was determined by multiple reinforcer variables within individual sessions, consistent with the concatenated matching law. However, in Experiment 2, there was a nonlinear (sigmoidal) relationship between response allocation and relative value, which suggests the possibility that reinforcer variables may interact during acquisition, contrary to the matching law.
鸽子在并发链程序中做出反应，其中终端链强化物变量在各实验阶段中不可预测地变化。在实验1中，终端链时间表为固定间隔（FI）8秒和FI 16秒，强化物大小分别为2秒和4秒。在实验2中，强化概率（100%或50%）随即时性和大小而变化。多元回归分析表明，鸽子在初始链中的反应分配由当前实验阶段的强化物变量决定，这与之前仅改变即时性的研究结果相似（格雷斯、布拉加松和麦克林，2003）。在两个实验中，所有强化物变量的敏感性系数均为正且具有统计学意义。对各实验阶段内反应的分析表明，在所有强化物变量都有利于同一终端链的主导实验阶段，最终的偏好水平比至少有一个强化物变量有利于每个选项的权衡实验阶段更为极端。这一结果意味着，反应分配由各实验阶段内的多个强化物变量决定，这与级联匹配法则一致。然而，在实验2中，反应分配与相对价值之间存在非线性（S形）关系，这表明强化物变量在习得过程中可能相互作用，这与匹配法则相反。
