Skinner and Thorndike

Skinner's Contributions to Thorndike's Conditioning Applied to Rat Olympics Many methods of conditioning have been used and will continue to be used in the training of the rats. Many of these methods come from theories and learning methods developed by Edward Lee Thorndike. However, many of the ways in which we implement these learning methods are slightly different than the way they were originally intended by Thorndike. The reason for this is the development of these learning methods through other learned psychologists such as B.F. Skinner. Skinner altered and added on to Thorndike's original theories about learning. We have implemented many of Skinner's ideas into our methods of training the rats. B.F. Skinner borrowed heavily from Thorndike in his work. This is reflected in many of the techniques and methods of thinking used when dealing with the Rat Olympics. Among these ideas are his views on positive reinforcement, punishment, shaping, and the continuous reinforcement schedule. Skinner added to Thorndike's theories of teaching when he addressed positive reinforcement vs. punishment. Skinner attacked the subject in depth, coming up with the conclusion that while punishment will fix a temporary problem, it tends to be the wrong way to go about doing things. His reasoning was that punishment does a good job of telling the rat what not to do, rather than what they should do. Skinner placed his emphasis on positive reinforcement. By providing positive reinforcement, the rat learns what it has to do. Indeed, that is its job: a positive reinforcer, either primary or secondary, is something that, when added to the situation by a certain response, increases the probability of that response recurrence (Hergenhahn 1992). The primary reinforcement method coupled with a punishment is used in training the rats to run through the obstacle course. The positive reinforcer is food waiting for them at the end of the course, while the punishment is the trainer picking the rat up and starting him over when he stalls or does an incorrect movement. Skinner also added to Thorndike's theories of learning by introducing "shaping", that is, a form of incremental learning akin to the childhood game of "hot- cold". In shaping, the rat is incrementally reinforced to perform an action: at first the rat may be rewarded for walking across a platform. He may then next time not get rewarded unless he steps across a small gap. Still then from there, he may be eventually forced to jump across a gap to get to the rest of the maze and to his reward. This can be coupled with Thorndike's principle of the law of effect, which states that an action that brings about a satisfying state of affairs will cause the connection between that action and good things to be stronger. Thus, the rat will make the connection that jumping across the gap and the pleasurable stimulus, and will therefore jump the gap in the future. Thorndike was very enthusiastic about the need to repeat actions to strengthen the associations involved therein. This principle lies with us today, as we all do homework and go to practice for various sports and activities. Skinner also believed in the use of a continuous reinforcement schedule: reinforcing the rat every time it performed a correct action. Again, the combination of the two merge and yield a rat that pairs the action/stimulus with the response of eventually getting food. Despite the success of the continuous interval reinforcement schedule at the outset of training, it does not produce the best results in the long run. To obtain optimal performance, it is necessary to start with a continuous interval and then move to a variable ratio reinforcement schedule (VR). The VR schedule operates by reinforcing the rat after a task has been completed a certain average number of times. It is important to note that it is an average number; thus, with the average being 5, the rat could be reinforced the seventh time, the second time, and so forth as long as they all grouped around every fifth time. This method is superior to the continuous reinforcement method because it produces both a greater resistance to extinction and higher response rates. This and other reinforcement schedules are proposed by Skinner, though we have not used them in this course so far. Hergenhahn, B.R. Olson, M.H. (1992). An Introduction To Theories of Learning. New Jersey: Prentice Hall.