Lydersen T
Fircrest School, 15230 15th Avene, N.E. Seattle, WA 98155-0550, USA.
Behav Processes. 1997 Jul;40(2):137-47. doi: 10.1016/s0376-6357(96)00770-x.
Four rats obtained food on fixed-time (FT) 1-, 4-, and 16-min schedules. During FT schedules, a lever press produced a timeout period during which food could not be delivered. When timeout was in effect, a lever press ended the timeout period and reinstated the FT schedule. In different conditions, the timing of the FT interval either stopped for the duration of the timeout period (Stop condition) or the timing of the FT interval continued during timeout (No Stop condition). The percentage of session time spent in timeout periods increased as the time between food deliveries increased regardless of whether or not timing of the FT interval stopped during timeout. The timeout percentage was larger on Stop than No Stop conditions if the obtained interfood interval was also longer. The rate of initiation of timeout periods tended to increase from FT 1-min to FT 4-min schedules, and then not increase further or decrease on FT 16-min. The mean time per timeout period tended to be similar on FT 1- and FT 4-min schedules and then increase on FT 16-min. A given percentage of session time spent in timeout periods appears to be due to interactions between rate of timeout, duration of timeout periods and interfood interval. The data are not consistent with the suggestion that timeout initiation represents escape from aversive aspects of intermittent reinforcement. Instead, choice of timeout shares some of the properties of facultative behaviors.
四只大鼠按照固定时间（FT）为1分钟、4分钟和16分钟的时间表获取食物。在FT时间表期间，按压杠杆会产生一个超时时间段，在此期间食物无法投递。当超时生效时，按压杠杆会结束超时时间段并恢复FT时间表。在不同条件下，FT间隔的计时在超时时间段内要么停止（停止条件），要么在超时期间继续计时（不停止条件）。无论FT间隔的计时在超时期间是否停止，随着食物投递间隔时间的增加，超时时间段内花费的会话时间百分比都会增加。如果获得的食物间隔时间也更长，那么在停止条件下的超时百分比比不停止条件下更大。超时时间段开始的速率从FT 1分钟时间表到FT 4分钟时间表有增加的趋势，然后在FT 16分钟时间表上不再进一步增加或减少。每个超时时间段的平均时间在FT 1分钟和FT 4分钟时间表上趋于相似，然后在FT 16分钟时间表上增加。在超时时间段内花费的给定百分比的会话时间似乎是由于超时速率、超时时间段的持续时间和食物间隔之间的相互作用。这些数据与超时开始代表从间歇性强化的厌恶方面逃脱的观点不一致。相反，超时的选择具有一些兼性行为的特性。
