Wilson A George, Matell Matthew S, Crystal Jonathon D
Department of Psychology, University of Kentucky, Lexington, KY, USA.
Learn Behav. 2015 Jun;43(2):153-62. doi: 10.3758/s13420-015-0169-y.
Memories for when an event has occurred are used to anticipate future occurrences of the event, but what happens when the event is equally likely to occur at two different times? In this study, one group of rats was always reinforced at 21 s on the peak-interval procedure (21-only group), whereas another group of rats was reinforced at either 8 or 21 s, which varied daily (8-21 group). At the beginning of each session, the behavior of the 8-21 group largely lacked temporal control, but by the end of the session, temporal control was reestablished. When both groups were reinforced at 21 s, the patterns of responding were indistinguishable after subjects in the 8-21 group had experienced 13 reinforcement trials. Finally, the reinforcement times of previous sessions affected the 8-21 group, such that subjects were biased depending on the reinforcement time of the prior session. These results show that when the reinforcement time is initially ambiguous, rats respond in a way that combines their expectations of both possibilities; then they incrementally adjust their responding as they receive more information, but still information from prior sessions biases their initial expectation for the reinforcement time. Combined, these results imply that rats are sensitive to the age of encoded temporal memories in an environment in which the reinforcement time is variable. How these results inform the scalar expectancy theory, the currently accepted model of interval-timing behavior, is discussed.
对事件发生时间的记忆用于预测该事件未来的发生情况，但是当该事件在两个不同时间发生的可能性相同时会发生什么呢？在本研究中，一组大鼠在峰值间隔程序的21秒时总是得到强化（仅21秒组），而另一组大鼠在8秒或21秒时得到强化，强化时间每天变化（8 - 21秒组）。在每个实验阶段开始时，8 - 21秒组的行为在很大程度上缺乏时间控制，但到实验阶段结束时，时间控制得以重新建立。当两组都在21秒时得到强化时，在8 - 21秒组的大鼠经历了13次强化试验后，反应模式变得难以区分。最后，前一实验阶段的强化时间影响了8 - 21秒组，使得大鼠根据前一实验阶段的强化时间产生偏向。这些结果表明，当强化时间最初不明确时，大鼠的反应方式结合了它们对两种可能性的预期；然后它们在接收更多信息时逐步调整反应，但前一实验阶段的信息仍然会使它们对强化时间的初始预期产生偏向。综合来看，这些结果意味着在强化时间可变的环境中，大鼠对编码的时间记忆的时效性很敏感。本文还讨论了这些结果如何为标量期望理论（目前被接受的间隔计时行为模型）提供信息。
