The effect of response cost and control of species typical behavior on a daily time-place learning task

Deibel, Scott (2011) The effect of response cost and control of species typical behavior on a daily time-place learning task. Masters thesis, Memorial University of Newfoundland.

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Abstract

Two theories, which have been hypothesized to mediate acquisition in daily time-place learning (TPL) tasks were investigated: the Response-Cost (RC) hypothesis and the Species-Typical Behaviours (STB) hypothesis. According to the RC hypothesis, rats only learn daily TPL tasks if there is high cost in either effort or time for making an incorrect choice. According to the STB hypothesis, rats learn the daily TPL tasks, however the intrusion of species typical behaviours such as patrolling mask evidence of this learning. Two experiments tested the validity of these hypotheses. Rats were trained that one lever at the end of one choice arm of a T-maze provided food in the morning and six hours later a lever in the other choice arm provided food. In Experiment 1, two groups tested the RC theory by manipulating the density of the reinforcement schedule used. A third group tested the importance of the STB by giving the rats time to patrol the maze prior to the start of the experiment. If only first arm choice data were considered there was little evidence of learning. However, both first press and percentage of presses on the correct lever, revealed of TPL in all groups tested. Unexpectedly, the low response cost group performed better than the high response cost group and the species typical behaviour group performed the worst. To control for the fact that the high response cost group was on the maze for a longer period of time than the rats in the other two groups, a second experiment was conducted. Experiment 2 also used a low response cost group and a species typical behaviour group, except these animals remained on the maze for the same amount of time as the rats in the high response cost group from Experiment 1. The additional time on the maze in Experiment 2 did not have an effect on performance. Skip session probe trials confirmed that the majority of the rats that acquired the task were using a circadian timing strategy. We outline two possible explanations which might account for the results from the present study.

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