Coleman Paul

Maze learning and open field behavior of adrenalectomized rats

Abstract Fifteen albino male rats were divided into three groups of five each: adrenalectomized, sham-operated control, and normal control. They were tested for learning ability on a four-unit T-maze (12 days after operation) and for activity level and “emotionality” in an open field (25 days after operation). Total body-weight and water intake were also recorded. There were no differences between groups in total body-weight, water intake, or ambulation in the open field. In the maze, however, early in learning controls made more errors than adrenalectomized animals. Later in maze learning the groups did not differ in number of errors, but the controls ran more quickly than the adrenalectomized animals. It is suggested that the intact animals are more reactive to the mild fear situation posed by the unfamiliar apparatus. This is supported by the fact that the adrenalectomized animals made fewer “emotional” responses in the open field situation than the controls.

Verbal discrimination reversal as a function of overlearning and percentage of items reversed: An extension

The S s received either 0 or 50% postcriterial trials on a verbal discrimination task. Following original training 25, 50, 75, or 100% of the items received a reversed reinforcement contingency. Main effects of degree of training and of percentage of items reversed were significant. The speed with which 100% reversal was obtained suggested that S s utilized a “concept of reversal” in this task.

Effects of Overlearning and Spatial Delay of Reinforcement upon a Discrimination Reversal

Rats were trained on a brightness discrimination task under two conditions of spatial delay of reinforcement. Groups received either 0 or 150 postcriterial trials and then were given reversal training. Reversal training was under either the same delay as experienced in original learning or the alternate one. The results indicated that the delay variable, ineffective in original learning, affected reversal acquisition. The postcriterial trials had no affect on trials to reversal criterion. Further analysis indicated that overtraining resulted in a greater number of initial responses to the originally positive stimulus early in reversal training.

Effects of overtraining and two non-correction training procedures upon a brightness discrimination reversal

The effects of overlearning and two non-correction training procedures upon the reversal of a black-white discrimination task were investigated. Overtraining and the Non-Entry procedure facilitated reversal learning.