Operant Conditioning

Operant Conditioning
At about the same time that Pavlov was conducting his experiments in Russia,
an American psychologist named Edward L. Thorndike (1874-1949) was
examining a different formof learning that has come to be called instrumental
or operant conditioning. Thorndike’s original experiments involved
placing cats in an apparatus he designed, which he called a puzzle box. A
plate of food was placed outside the puzzle box, but the hungry cat was
trapped inside. Thorndike designed the box so that the cat needed to make
a particular response, such as moving a lever or pulling a cord, in order for a
trap door to be released, allowing escape and access to the food outside. The
amount of time it took the cat to make the appropriate response was measured.
With repeated experience, Thorndike found that it took less and less
time for the cat to make the appropriate response.
Operant conditioning is much different from Pavlov’s classical conditioning.
As was stated before, classical conditioning involves learning “what
goes with what” in the environment. Learning the relationship changes behavior,
though behavior does not change the environmental events themselves.
Through experience, Pavlov’s dogs began to salivate when the bell was rung, because the bell predicted food. However, salivating (the CR) did
not cause the food to be delivered. Thorndike’s cats, on the other hand, received
no food until the appropriate response was made. Through experience,
the cats learned about the effects of their own behavior upon environmental
events. In other words, they learned the consequences of their own
actions.
To describe these changes, Thorndike postulated the Law of Effect. According
to the Law of Effect, in any given situation an animal may do a variety
of things. The cat in the puzzle box could walk around, groom itself,
meow, or engage in virtually any type of feline behavior. It could also make
the operant response, the response necessary to escape the puzzle box and
gain access to the food. Initially, the cat may engage in any of these behaviors
and may produce the operant response simply by accident or chance. However,
when the operant response occurs, escape from the box and access to
the food follows. In operant conditioning terminology, food is the reinforcer,
(Sr, or reinforcing stimulus) and it serves to strengthen the operant
response (R) that immediately preceded it. The next time the animal finds
itself in the puzzle box, its tendency to produce the operant response will be
a bit stronger as a consequence of the reinforcement. Once the response is
made again, the animal gains access to the food again—which strengthens
the response further. Over time, the operant response is strengthened,
while other behaviors that may occur are not strengthened and thus drop
away. So, with repeated experience, the amount of time that it takes for the
animal to make the operant response declines.