4. Reflexology.
Descartes' dualism involved the as-
sumption that the behavior of the body, below the level
of willed
action, could be explained mechanically. He
had, however, a crude idea of
how the body works.
He thought of it as a statue or machine made of
earth
and was much impressed by the feats which mechanical
manikins
could be made to perform in the gardens
of the aristocracy by arranging
water-pipes within
them. They could be made to move their limbs and
even to produce sounds like words. He thus pictured
the nervous system as a
piece of intricate plumbing.
The nerves were thought of as tubes along
which
“animal spirits,” which occupied an
indeterminate
status between the mental and the physical, flowed
continuously. Changes in the motion of these spirits
cause them to open
certain pores in the brain. When
this happens the motion of the animal
spirits is changed
and they are “reflected” into the
muscles which move
the body. For he thought that many movements of the
body are not brought about by conscious intention, but
by an undulatio reflexa, or a movement of rebound
in the
animal spirits at the meeting of the sensory and
motor channels at the
pineal gland, where the mind
could also influence the body by means of
images. The
automatic reactions of the body, which were not under
voluntary
control, were thus called reflexes.
Little was done to refine this conception until 1811
when Charles Bell
published a paper entitled “An Idea
of a New Anatomy of the
Brain,” which he communi-
cated
to the Royal Society in 1821, and in which he
claimed that the nerves,
which are connected with the
spinal centers by anterior roots, are employed
in con-
veying motor impulses from the brain
outward, and
that the sensory nerves are connected with the poste-
rior roots of the spinal cord. This was
confirmed by
Magendie in 1822. In 1833 Marshall Hall demonstrated
clearly the existence of reflex action which proceeded
independently of
conscious volition, and in the latter
part of the nineteenth century the
antics of animals
deprived of their higher brain structure were a com-
monplace. In 1851 Claude Bernard
pioneered physio-
logical work on the
influence of specific nerves on the
blood vessels and the consequent
changes throughout
the sympathetic system, thus helping to understand
the
connection between the brain and the viscera and other
changes
involved in emotional and motivational states.
Evolutionary theory,
especially that of Herbert
Spencer, led Hughlings Jackson to postulate
different
levels of evolution in the nervous system from the less
to
the more organized, from the automatic to the
voluntary.
From the point of view of the history of behaviorism
the crucial step
forward was taken by Pavlov, whose
particular interest was in the digestive
system. In 1897
he published a book on The Work of the
Digestive
Glands, in which he noted that there are certain ir-
regularities and interruptions in the
work of these
glands, which he attributed to psychic causes, e.g.,
that
sometimes the glands would start to work before food
was given to
a dog, when the dog saw the man who
usually fed it. In 1902 he embarked on
a long series
of experiments to study such phenomena. He concen-
trated on salivation, rather than on
gastric secretion,
because it was more accessible to experimental analy-
sis. A dog was strapped in a test frame,
with elaborate
experimental controls, and a bell (conditioned
stimulus)
was repeatedly sounded before food (unconditioned
stimulus)
was placed in the mouth to produce salivation
(unconditioned response),
until eventually the sound
of the bell brought about salivation
(conditioned re-
sponse) before the
presentation of the food. Pavlov also
found that the conditioned stimulus
becomes general-
ized, in that the dog comes
to respond to a wide range
of stimuli. He found, too, that dogs could be
taught
to discriminate between stimuli by rewarding responses
to one
stimulus, such as a circle, but not to another,
such as an ellipse. If the
difference between the stimuli
was gradually reduced a point would be
reached where
the dog's behavior evinced all the symptoms of acute
neurosis.
The concept of “reinforcement” was invented
to refer
to this process in which the conditioned stimu-
lus is presented in close juxtaposition to the uncondi-
tioned stimulus. Many have commented on the simi-
larity between this concept and that of
Thorndike's
“reward,” central to his law of effect.
But the two
concepts emerged from very different theoretical
backgrounds and their differences are as important as
their similarities
(Wolman [1960], pp. 53-55).
Pavlov was unrepentantly a physiologist and he
linked his experimental
findings with a theory about
irradiation and processes of excitation and
inhibition
in the brain. He expressed contempt for psychology
and
refused to take sides in psychological controversies.
Nevertheless his
influence has been nugatory in physi-
ological theory but vast in psychology, because the
behaviorists
later seized upon his findings. His contem-
porary, Bekhterev, on the other hand, who also popu-
larized the conditioned reflex, was more catholic in
his interests. In 1907 he published his Objective Psy-
chology in which he proclaimed
that the future of
psychology depended upon objective, external obser-
vation. He envisaged excluding
introspective data and
mentalistic concepts and basing psychology on
physical
and physiological findings. In this respect Bekhterev
harped
back to La Mettrie and the materialistic tradi-
tion in psychology. In his conditioning experiments he
did not
confine himself to reactions such as salivation
but met with some success
in conditioning motor re-
sponses as well. He
also took an interest in speech,
as also did Pavlov towards the end of his
life.
Watson embarked upon his behavioristic program
in ignorance of the
physiological studies of Pavlov and
Bekhterev, but he gradually
incorporated them into
his theory when he became familiar with them
through
translation. Thus Watson's reflexes functioned in his
theory
as the direct descendants of Descartes' “simple
natures” in the bodily sphere. The links between them,
however,
namely the principles of association, and the
assumptions about how
generalizations could be ar-
rived at about such
links, came from another source—
the empiricist tradition. A
brief exposition of the lead-
ing ideas of this
tradition will complete the account
of behaviorism's intellectual ancestry.
