van Haaren F, Zarcone T
Department of Psychology, University of Florida, Gainesville FL 32611, USA.
Behav Processes. 1994 Apr;31(2-3):197-206. doi: 10.1016/0376-6357(94)90006-X.
Three male and three female rats were first trained to respond on a Random-Interval 15-s schedule on one (food) lever in a rodent operant conditioning chamber. They were then exposed to a condition in which food could only be obtained during a timein period which lasted 10 s or longer dependent upon whether or not subjects pressed another (avoidance) fever. If subjects did not press the other level during the 10-s timein, a 50-s timeout was presented during which food could not be obtained. Subjects first had the opportunity to avoid timeout presentation by pressing the avoidance level during timein or to escape the timeout by pressing the lever during timeout. A changeover delay of 2-s prevented food presentation immediately following avoidance lever-food lever sequences. All subjects pressed the avoidance lever to avoid or escape timeout, but only one of the subjects consistently pressed the avoidance lever when escape was no longer available. One more subject acquired consistent avoidance responding after reexposure to the avoidance/escape and avoidance only conditions. The four remaining subjects were then exposed to a signalled avoidance procedure in which a 5-s stimulus change preceded timeout presentation. Three of the subjects came to respond reliably on the avoidance lever when switched back to the unsignalled avoidance procedure. One of the subjects never acquired consistent avoidance responding. Functional control by the avoidance contingency was demonstrated during the final two experimental conditions in which the contingencies associated with the avoidance lever were systematically removed and reintroduced.
三只雄性和三只雌性大鼠首先在啮齿动物操作性条件反射箱中接受训练，在一个（食物）杠杆上按照随机间隔15秒的时间表做出反应。然后，它们被置于一种条件下，即只有在一个持续10秒或更长时间的进食期内，根据实验对象是否按压另一个（回避）杠杆，才能获得食物。如果实验对象在10秒的进食期内没有按压另一个杠杆，就会出现50秒的超时，在此期间无法获得食物。实验对象首先有机会通过在进食期内按压回避杠杆来避免超时出现，或者通过在超时期间按压杠杆来逃离超时。2秒的转换延迟可防止在回避杠杆-食物杠杆序列之后立即呈现食物。所有实验对象都按压回避杠杆以避免或逃离超时，但只有一只实验对象在无法逃离时仍持续按压回避杠杆。在再次暴露于回避/逃离和仅回避条件后，又有一只实验对象获得了持续的回避反应。其余四只实验对象随后被置于一种有信号的回避程序中，在超时出现前有一个5秒的刺激变化。当切换回无信号的回避程序时，其中三只实验对象开始在回避杠杆上可靠地做出反应。有一只实验对象从未获得持续的回避反应。在最后两个实验条件中，与回避杠杆相关的意外情况被系统地消除和重新引入，从而证明了回避意外情况的功能控制。
