The Study of Behavior Development by Watson, Pavlov, Thorndike, and Skinner
Behaviorists believe that psychology should focus on measureable and observable physical behaviors and how these behaviors can be manipulated by changes in the external environment. There is no room in behaviorist theory for thoughts or emotions, a contrast to other theories of psychology.
John Watson was the founder of behavorist theory. Quite innovatively for the time, he found Freudian-based explanations of behavior too theoretical and disagreed with the eugenic idea of heredity determining how one behaves.
Instead, he believed that people's reactions in various situations were determined by how their overall experiences had programmed them to react.
In experiments he performed in the early 1900s he showed that he could condition, or train, children to respond to a certain stimulus in a way that was different from what their normal response would be in the absence of such training.
For example, one infant named Albert who had previously liked and attempted to pet a white rat was later conditioned by Watson to come to fear it.
This was done by producing loud clanging noises whenever the rat was brought into Albert's line of sight; in a few weeks time, the rat alone could induce tears and an attempted flight response by the terrified baby. Because Watson repeatedly stimulated Albert to feel fear when the rat was present, the infant's experiences taught it to be afraid around rats and react accordingly.
Albert not only feared rats but had been programmed through the experiment to fear most other white and fuzzy objects as well, from coats to Santa Claus beards.
Ivan Petrovich Pavlov was the first to introduce the concept of conditioning through his experiments with animals. His conclusions directly influenced Watson and provided him with the original scientific basis for his beliefs.
In these experiments, Pavlov worked with dogs that, like most, salivated naturally in the presence of food. Because this respone is innate, the animals were displaying an unconditioned response (salivation) to an unconditioned stimulus (food). Pavlov then, for the sake of experimentation, began to produce a metronome sound at the time of each feeding. Eventually, the dogs started to drool after hearing it and in anticipation of food, even when none was present.
At the end of his experiments, Pavlov was able to condition, or teach, these dogs to salivate in unnatural situations (after hearing a sound) to stimuli which would normally not ellicit that response (sound). In essence, Pavlov had transformed salivation into a conditioned behavior and the metronome had become a conditioned stimulus.
Pavlov further discovered that conditioned behaviors of this type would disappear if they failed to deliver the expected outcome; for example, if the metronome was sounded repeatedly and no food was presented, dogs would eventually stop associating the two and their drooling response to the sound would vanish.
Edward Thorndike came up with the concept of intrumental conditioning and, like Pavlov, reached his main conclusions using data gained through animal-based experimentation.
Such experiments included placing hungry cats in an enclosed container, which Skinner referred to as a puzzle box, from which they had to escape in order to reach food. The first time a cat was placed in this situation it escaped only after several failed attempts and a single lucky successful guess (such as pushing the right button). However, the time it took to escape decreased each time a cat was returned to the box.
This meant, first of all, that the cats remembered which behavior was necessary to escape and get the reward of food. If they had not, it would take approximately the same time for them to refigure it out and there would not be the trend of a continually faster escape. Secondly, they were clearly able to recognize their current situation (being placed in the puzzle box) was identical to the last time they were placed inside of the puzzle box, and therefore that the same successful behavior used before would achieve the same end result the next time around: freedom and a feast.
Using his data Thorndike developed two main laws concerning conditioning. The first was the law of exercise, stating simply that the repetition of a response strengthens it. Each time a cat was placed in the puzzle box it exhibited a stronger inclination to perform the behaviors required, exiting the box with increased proficiency and in a shorter time span.
The second law, the law of effect, established that behaviors were either strengthened or weakened, depending on whether they were rewarded or punished. Each time the successful behavior was repeated, it was done so more quickly because the cat no longer wasted time performing other behaviors which had proven unsuccessful and kept the animal imprisoned.
B.F. Skinner developed the behavorist theory of operant conditioning. Contrary to the theories of both Watson and Pavlov, Skinner believed that it wasn't what comes before a behavior that influences it, but rather what comes directly after it.
In operant conditioning behaviors are manipulated when they are followed by either positive or negative reinforcement. Positive reinforcement increases desired behaviors by following them with rewards. For example, if rat food is dispensed every time a rat pushes a pedal, it will repeatedly push that same pedal to get more edible treats. The action of pushing the pedal, the desired behavior, has been reinforced with food.
Negative reinforcement increases desired behaviors by allowing subjects to escape punishment through their performance. For example, if a rat received a painful electrical jolt that would not cease unless it pressed a pedal, it would begin to press it quickly following each initial jolt to relieve its pain. The action of pushing the pedal, the desired behavior, has again been reinforced, though by a different method then before.
Skinner also showed that behaviors can be altered through punishment or extinction. Punishing behaviors after they occur discourages them from being later repeated. For example, if a rat was jolted with electricity when it pressed a pedal, it would begin to avoid touching it, avoiding performing the undesireable behavior.
Extinction is when behaviors that were previously reinforced are later uninforced, rendering the behaviors inconsequential and causing them to decrease in frequency over time. If the rat that had been trained to push a pedal for food ceased receiving food for pressing it, eventually it would press it less and less often. In time, after it has become thoroughly discouraged by the lack of dispensed rat treats, it may stop pressing it altogether.
If the rat that was zapped with electricity stopped being zapped, it would also push the pedal to stop the voltage less frequently, as its reason for doing so would be gone. Extinction is the discontinuation of behaviors that had been encouraged by either negative or positive reinforcement.