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In this experiment it was expected that as discrimination training progressed, the rats would learn to discriminate between the SD and Sd conditions, and that behavior in the reinforced condition would increase, while behavior in the non-reinforced condition would decrease. This hypothesis was supported. This experimental group of rats had learned to discriminate by the second session of discrimination training.
Thorndike found that once a subject had solved the problem presented to it, successive trials of the same problem took much less time (Keller and Schoenfeld, 1950). In the experiment detailed here, the experimental data supports this. Once the rats had learned to discriminate between the SD and Sd conditions, there was usually very little wasted time. Once the SD condition was presented, the rats started immediately to bar press for food, and when the Sd condition was presented, the rats usually stopped pressing the bar. The results of this experiment can be explained by Thorndike's three laws. As explained by the Law of Effect, since bar pressing produced satisfying consequences, an association was formed which produced repeated bar pressing in the reinforced condition. With repeated exercise connections between the SD condition and primary reinforcement were strengthened, and bar pressing increased, while the bar pressing behavior during the non-reinforced Sd condition was weakened. By putting the rats on a food deprivation schedule the rats were motivated and ready to provide the required response, i. e. bar pressing for during the SD condition.
Dinsmoor (1950) conducted an experiment in which he used a light-on and light-off condition as SD and Sd in which the rats learned to discriminate between the 2 conditions, and that the behavior in the reinforced condition increased, while behavior in the non-reinforced condition decreased. In this experiment there was a 49% increase in the rate of bar pressing in the SD condition, and a 62% decrease in the rate of bar pressing in the Sd condition. These results are in agreement with Dinsmoor's findings.
In Smith and Hoy's (1954) experiment, they found that once discrimination train had begun, that the rate of bar pressing in the SD and Sd condition remained a constant. These experimental results were later refuted by Herrick et al. (1959), and the current experiment does show that the number of bar presses was essentially a constant once discrimination training had begun, therefore, the results of this experiment are in agreement with
Smith and Hoy(1954).
In the experiment by Egger and Miller (1962), in which they investigated the effects of secondary reinforcement, they found that when a second stimulus was informative, the behavior would be reinforced, and likely repeated. In the current experiment, there was not a conscious effort to use a second stimulus as secondary reinforcement, however, several experimenters noticed that when reinforcement was available, the feeder mechanism made a noise when the bar was pressed, and this quite frequently acted as a second stimulus. An example of this behavior was, if the rat pressed the bar, just after the SD condition had resumed, and the noise of the feeder mechanism was heard, the rats "seemed" to gain renewed interest in bar pressing.
Several of the experimenters observed other experimenters bonding with the rats under their care during experimental observation. These experimenters were giving verbal reinforcement and visual stimuli to their rats, in an effort to try to get the rats to come to the bar mechanism. It is not known if this behavior had any effect on the experimental data. However, such behavior would be a topic for a future experiment with tighter controls for verbal an visual stimuli presented to the subjects.
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