A summary of their work
Ivan Pavlov (1849 – 1936)
Ivan Pavlov was born in a small village in central Russia. The work that made Pavlov a household name in psychology actually began as a study in digestion. He was looking at the digestive process in dogs, especially the interaction between salivation and the action of the stomach. He realized they were closely linked by reflexes in the autonomic nervous system. Without salivation, the stomach didn't get the message to start digesting. Pavlov wanted to see if external stimuli could affect this process, so he rang a bell at the same time he gave the experimental dogs food. After a while, the dogs -- which before only salivated when they saw and ate their food -- would begin to salivate when the bell rang, even if no food were present.
In 1903 Pavlov published his results calling this a "conditioned reflex," which is different from an innate reflex, such as yanking a hand back from a flame, in that it had to be learned. Pavlov called this learning process (in which the dog's nervous system comes to associate the bell with the food, for example) "conditioning." He also found that the conditioned reflex will be repressed if the stimulus proves "wrong" too often. If the bell rings repeatedly and no food appears, eventually the dog stops salivating at the bell.
Edward L. Thorndike (1874 – 1949)
Edward Thorndike was an American educator and psychologist born in Williamsburg, Massachusetts. The learning theory of Thorndike represents the original S-R (Stimulus-Response)framework of behavioural psychology: learning is the result of associations forming between stimuli and responses. Such associations or "habits" become strengthened or weakened by the nature and frequency of the S-R pairings.
The paradigm for S-R theory was trial and error learning in which certain responses come to dominate others due to rewards. The classic example of Thorndike's S-R theory was a cat learning to escape from a "puzzle box" by pressing a lever inside the box. After much trial and error behaviour, the cat learns to associate pressing the lever (S) with opening the door (R). This S-R connection is established because it results in a satisfying state of affairs (escape from the box).
As a result of studying animal intelligence, he formulated his famous "laws of learning".
Law of readiness: This states that when an organism is ready to act it's reinforcing for it to do so and when an organism is not ready to act, forcing it to act will be annoying to it.
Law of exercise: This law states that those things most often repeated are best remembered, that is, practice strengthens the connection and disuse weakens it.
Law of effect: This law states that the strength of a connection is influenced by the consequences of a response.
Burrhus Frederic Skinner (1904 – 1990)
Skinner was born in Pennsylvania, USA and he is regarded as the father of Operant Conditioning. Operant conditioning:behaviour is also affected by its consequences, but the process is not trial-and-error learning. It can best be explained with an example. A hungry rat is placed in a semi-soundproof box. For several days bits of food are occasionally delivered into a tray by an automatic dispenser. The rat soon goes to the tray immediately upon hearing the sound of the dispenser. A small horizontal section of a lever protruding from the wall has been resting in its lowest position, but it is now raised slightly so that when the rat touches it, it moves downward. In doing so it closes an electric circuit and operates the food dispenser. Immediately after eating the delivered food the rat begins to press the lever fairly rapidly. The behaviour has been strengthened or reinforced by a single consequence. The rat was not "trying" to do anything when it first touched the lever and it did not learn from any "errors."
Robert Gagné (1916 - 2002)
Robert Gagné was born in the USA and he is best known for his "Conditions of Learning". His theory supports the following ideas:
- Learning causes an observable change in the learner.
- Skills should be learned one at a time.
- Each new skill learned should build on previously acquired skills.
- Learning and knowledge are both hierarchical in nature.
A learner event includes a learner, a stimulus situation (events that stimulate the learner's senses) and an action or response that results from the stimulation. He distinguished 8 different classes of situations in which human beings learn.
- Signal Learning: the individual learns to make a general, diffuse response to a signal. Such was the classical conditioned response of Pavlov.
- Stimulus-Response Learning: the learner acquires a precise response to a discriminated stimulus.
- Chaining: a chain of two or more stimulus-response connections is acquired.
- Verbal Association: the learning of chains that are verbal.
- Discrimination Learning: the individual learns to make different identifying responses to many different stimuli which may resemble each other in physical appearance.
- Concept Learning: the learner acquires a capability of making a common response to a class of stimuli.
- Rule Learning: a rule is a chain of two or more concepts.
- Problem Solving: a kind of learning that requires the internal events usually called thinking.