Dunn R, Spetch M L
Department of Psychology, San Diego State University, Calexico, California 92231.
J Exp Anal Behav. 1990 Mar;53(2):201-18. doi: 10.1901/jeab.1990.53-201.
Pigeons responded on concurrent chains with equal initial- and terminal-link durations. In all conditions, the terminal links of one chain ended reliably in reinforcement; the terminal links on the alternative chain ended in either food or blackout. In Experiment 1, the terminal-link stimuli were correlated with (signaled) the outcome, and the durations of the initial and terminal links were varied across conditions. Preference did not vary systematically across conditions. In Experiment 2, terminal-link durations were varied under different stimulus conditions. The initial links were variable-interval 80-s schedules. Preference for the reliable alternative was generally higher in unsignaled than in signaled conditions. Preference increased with terminal-link durations only in the unsignaled conditions. There were no consistent differences between conditions with and without a common signal for reinforcement on the two chains. In the first series of conditions in Experiment 3, a single response was required in the initial links, and the stimulus conditions during 50-s terminal links were varied. Preference for the reliable outcome approached 1.0 in unsignaled conditions and was considerably lower (below .50 for 3 of 5 subjects) in signaled conditions. In a final series of signaled conditions with relatively long terminal links, preference varied with duration of the initial links. The results extend previous findings and are discussed in terms of the delay reduction signaled by terminal-link stimuli.
鸽子在初始链节和终端链节时长相等的并发链上做出反应。在所有条件下，一条链的终端链节可靠地以强化结束；另一条链的终端链节则以食物或停电结束。在实验1中，终端链节刺激与结果相关（发出信号），并且初始链节和终端链节的时长在不同条件下变化。偏好并未在不同条件下系统地变化。在实验2中，终端链节时长在不同刺激条件下变化。初始链节采用可变间隔80秒的时间表。在无信号条件下，对可靠选项的偏好通常高于有信号条件。仅在无信号条件下，偏好随终端链节时长增加。两条链上有强化共同信号和无强化共同信号的条件之间没有一致的差异。在实验3的第一组条件中，初始链节只需一次反应，50秒终端链节期间的刺激条件变化。在无信号条件下，对可靠结果的偏好接近1.0，而在有信号条件下则相当低（5名受试者中有3名低于0.50）。在最后一组有相对长终端链节的有信号条件下，偏好随初始链节的时长而变化。这些结果扩展了先前的发现，并根据终端链节刺激发出信号的延迟减少进行了讨论。
