Evening star., 1935-10-26
STARS, MEN AND ATOMS
ok of Science Progress in Field,
Laboratory and Study.
BY THOMAS r. HENRY.

Changing the personality" of a sheep
is reported by DR.. o. D. Anderson, Ma
tional Research Council fellow. and DR..
H B. Liddell of Cornell University.
Upon the experiment. described in the
current issue of the Archives of Psy-
chiatry and Neurology, may depend far
reaching implications as to the mech
anism of personality differences in the
brains of other animals and men. The
fact that the sheep is one of the most
stupid of animals and one of the last to
be suspected of having any personality"
to be changed makes the results all the
more significant.
1t was found possible to bring about a
nervous breakdown" to change an ordi-
narily placid and cooperative animal
into a restless and resisting one, and
to repeat the process by the same meth
ods. The celebrated Russian physiol-
ogist, Pavlov, did the same thing with
dogs several years ago and upon his re-
suits have been built up some of the
current theories in education and child
training The work of Anderson and
Liddell, however, indicates that Pavlov'S
theory of how it happened was wrong.
The two experimenters were trying to
study conditioned ref1exeS in sheep. They
would give the animal a mild electric
shock, not painful. but strong enough to
make it lift one of its legs. Simultane-
ously with the shock, or just before it,
q noise of some sort would be made-in
these cases the ticking of a metronome.
After many trials the sheep would raise
its leg at the tick, without waiting for
the shock. Once the conditioned reflex
was established they set to work to refine
it. The shock was made to follow. after
a brief interval, definite number of
ticks. They started with five and soon
had the sheep to the point where it
would raise its leg on the fifth tick. Then
they increased the number of ticks up
to 20, and also the number of trials a
day. The result was that the animal
was put under greater and greater ten
sion. AS the period of the ticks increased
there was required more and more inhi-
bition of the impulse to move before the
final sound, which was the signal for the
shock, was heard.
Quite suddenly the characteristic be-
havior of the animal underwent
marked change. 1t had to be dragged
to the platform where once it>had gone
eagerly in search of oats. 1t became
restless, excitable and unmanageable.
The placid sheep had suffered ''nerv-
Gus breakdown" Only long vacation
in the pasture restored it to normal.
That was essentially what had hap
pened to Pavlovs dogs. The difference
was that this sheep and others used in
later experiments who reacted in the
same way, had often been used in maze
learning experiments where, in order to
escape from simple maze, it was neceS-
sary to learn the way through process
of trial and error. The sheep had proved
almost incredibly stupid. One of them
had spent three years, with repeated
trials, without being able to learn for
itself the intricacies of the simple laby-
rinth. Yet there had been no nervous
breakdowns, as might have been postu-
lated from the Pavlov dog experiments.
Pavlov found that his dogs went crazy
at some point, differing with different
animals, when the fineness Of diScrimi-
nation required by the conditioned reflex
became too great for the brain to make.
Upon the results he built up his BRAIN
balance theory. The brain, he held, had
semi-balanced potentialities for action or
resistance. Both were called into play