Biology Reference
In-Depth Information
Darwin concluded that temperament traits in domestic animals are inherited.
He also believed, as did many other scientists of his time, that animals had
subjective sensations and could think. Darwin wrote: “The differences in mind
between man and the higher animals, great as it is, is certainly one of degree
and not of kind.”
Other scientists realized the implications of Darwin's theory on animal
behavior and conducted experiments investigating instinct. Herrick (1908)
observed the behavior of wild birds in order to determine, first, how their
instincts are modified by their ability to learn, and second, the degree of
intelligence they attain. On the issue of thinking in animals, Schroeder (1914)
concluded: “The solution, if it ever comes, can scarcely fail to illuminate,
if not the animal mind, at least that of man.” It is evident that by the end of
the 19th century, scientists studying animal behavior in natural environments
learned that the mechanical approach could not explain all behavior.
BEHAVIORISM
During the middle of the 20th century, scientific thought again reverted to
the mechanical approach and behaviorism reigned throughout America. The
behaviorists ignored both genetic effects on behavior and the ability of animals
to engage in flexible problem solving. The founder of behaviorism, J.B. Watson
(1930) , stated, “differences in the environment can explain all differences
in behavior.” He did not believe that genetics had any effect on behavior.
In “The Behavior of Organisms,” the psychologist B.F. Skinner (1958) wrote
that all behavior could be explained by the principles of stimulus
response and
operant conditioning.
The first author visited with Dr Skinner at Harvard University in 1968.
Skinner responded to a question about the need for brain research by saying,
“We don't need to know about the brain because we have operant conditioning”
( Grandin and Johnson, 2005 ). Operant conditioning uses food rewards and
punishments to train animals and shape their behavior. In a simple Skinner
box experiment, a rat can be trained to push a lever to obtain food when a green
light turns on, or to push a lever very quickly to avoid a shock when a red light
appears. The signal light is the “conditioned stimulus.” Rats and other animals
can be trained to perform a complex sequence of behaviors by chaining together
a series of simple operant responses. Skinner believed that even the most
complex behaviors can be explained as a series of conditioned responses.
However, in a Skinner box a rat's behavior is very limited. It's a world
with very little variation, and the rat has little opportunity to use its natural
behaviors. It simply learns to push a lever to obtain food or prevent a shock.
Skinnerian principles explain why a rat behaves a certain way in the sterile
confines of a 30
30 cm Plexiglas box, but they don't reveal much about
the behavior of a rat in the local dump. Outside of the laboratory, a rat's
behavior is more complex.
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