The 1930s: Behavioral Objectives and Formative Evaluation

This material is provided by Robert Kentridge, University of Durham, England.
His complete lecture may be found at: http://www.dur.ac.uk/~dps1rwk/comp6.html

Cognition and Learning in the 1930s

In the 1920's behaviorism began to wane in popularity somewhat. A number of studies in the Berkeley laboratory of Edward Tolman appeared both to show flaws in the law of effect and require mental representations in their explanation. For example, rats were allowed to explore a maze in which there were three routes of different lengths between the starting position and the goal. The rats behavior when the maze was blocked implied that they must have some sort of mental map of the maze. The rats prefer the routes according to their shortness, so, when the maze is blocked at point A, stopping them using the shortest route, they will choose the second shortest route. When, however, the maze is blocked at point B the rats does not retrace his steps and use route 2, which would be predicted according to the law of effect, but rather uses route 3 . The rat must be recognizing that block B will stop him using route 2 by using some memory of the layout of the maze.

Tolman's group also showed that animals could use knowledge they gained learning a maze by running to navigate it swimming and that unexpected changes in the quality of reward could weaken learning even though the animal was still rewarded. This result was developed further by Crespi who, in 1942, showed that unexpected decreases in reward quantity caused rats temporarily to run a maze more slowly than normal while unexpected increases caused a temporary elevation in running speed - effects Crespi referred to as depression and elation!