J Exp Anal Behav. 1972 May;17(3):395-403. doi: 10.1901/jeab.1972.17-395.
Pigeons trained to peck one of two keys for food were exposed to an ascending and descending series of fixed-interval values. A response on the second key produced an escape period consisting of a visual stimulus change. During escape periods, the fixed-interval timer continued to operate and even if it timed out, a response on the food key would not operate the feeder unless preceded by an escape-key response that terminated the escape condition. As the fixed-interval schedule was increased logarithmically through six values from 30 to 960 sec, the percentage of session time spent in escape as well as the frequency, duration, and rate of escape increased to a maximum and then decreased. One subject did not develop escape behavior to any significant degree. For all pigeons, escapes usually occurred after, rather than before, reinforcement.
鸽子被训练啄两个键中的一个来获取食物,然后让它们接触一系列递增和递减的固定时距值。在第二个键上啄食会产生一个逃脱期,包括视觉刺激的改变。在逃脱期间,固定时距定时器继续运行,即使它超时了,如果在食物键上的反应之前没有逃脱键的反应来终止逃脱条件,那么喂食器也不会启动。当固定时距时间表从 30 秒到 960 秒以对数方式增加六个值时,在逃脱期内花费的时间百分比以及逃脱的频率、持续时间和速度都增加到最大值,然后再减少。有一个实验对象没有发展出显著程度的逃脱行为。对于所有的鸽子来说,逃脱通常发生在强化之后,而不是之前。