Table Of Contentw b ig x ig i as a mmorxoM up %m
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AND iCtTIKCTIOS
by .
Wararoa H. feichner
State University of Iowa
LIBRARY
A dissertation submitted in partial fulfillment ot the req.uirments
for the degree of doctor of Philosophy in the department
of Psychology in the Graduate Go liege of the
State University of Iowa
February 1951
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fhe writer wishes to express his sincere appreciation to
Professor Kenneth W, Spence, under whose direction the research was
conducted, for many helpful suggestions and criticisms throughout the
course of the investigation*
fABLE Of Q iw m m
page
Chapter I Introduction. • * . * ♦ * • • * • . # # • 1
Chapter II Statement of the Problem* • • • • * # * • 7
Ghapfcerlll Experimental Method* • • • • • • * • • . 8
Chapter XV Resulta. IS
Chapter V Discussion of Results. » * * • * . « * « 26
Chapter VI Summary and Conclusions* . * . » * « . . 31
Appendix*............................ * * • • 32
Bibliography* * • * * * • • * * • • • * * • • « • • 36
lit
TABU 0? FIGURES
Pago
Figure I 100 X the Reciprocal of the
Median Latencies Luring Learning, . .. 14
Figure XX Mean Reciprocal of the Median
Latency Luring the Last Third of
Learning as a Function of the
Intertrial Interval. . . . . . . . . . 17
Figure XIX Percent Frequency of Response for
Pairs of Latino lion Trials Rader Five
Riff©rent latertrial Intervals
Following Learning With a 45 Second
Interval. . . . . . . . . . . . . . . 18
Figure IY Extinction as a Function of the
Intertrial Interval Luring Extinction
for the Three Learning Conditions.
Bach Curve Represent© Extinction With
Various Extinction Intervals Following
a Constant Interval Luring Training. « 20
Figure Y Extinction as a function of the Time
Interval Between Conditioning Trials
for four Extinction Conditions. . . . 25
Iv
s m s 02? tab les
page
.
Table I Experix&entai Uesiga. . . . . . . . . . 11
Table II Means and Standard Errors of the
Means fop the Kecipi'oeal X 100 of
the Median Latencies of id© Last
Third of Learning. . . . . . . . . . . . 15
Table ill Summary Table of the Analysis of
Variance Performed on the Measures in
.
figure IV* ......................................... El
Table IV Summary Table of the Analyses of
Variance of Each Ourt© in figure IV. • . E3
V
1
Chapter I
INTRODUCTION
Experimental extinction or the decrement in the strength of
a conditioned response with failure of presentation of the unconditioned
or reinforcing stimulus, has been interpiieted in a number of different
ways. In general these formulations fall into three classess (1) those
that assume that some inhibitory state or process is developed during
extinction which is responsible for the weakening of the response;
(2) those that deny the necessity of postulating a special inhibitory
factor and rely solely on a competing* excitatory process* and (3) two
factor theories that make use of both types of processes*
m&t prominent of the theories of the first class is that of
Pavlov (©)« Basing his theory on hi® work with the conditioned sali
vary response in dogs* Pavlov introduced the concept of a state of
internal inhibition* This inhibitory state* he hypothesised* was op
posed by the excitatory state or tendency that the conditioned stimulus
acquired to evoke the conditioned response as the result of the occur
rence of the unconditioned or reinforcing stimulus* During conditioning
the cumulative increase in strength of the excitatory state proceeded at
a faster rate than that of the inhibitory state unless the trials were
presented in too rapid succession. With massing of trials the inhibitory
state* which in contrast to the excitatory state was assumed to be
labile and dissipate with time# might develop at a faster rate than ex
citation and lead to a decrement in response (inhibition of conditioning)*
2
With experimental extinction the strength of the conditioned response*
which is conceived to he the algebraic resultant of the two hypothetical
states of excitation and inhibition* becomes weakened as only inhibition
is developed during this procedure*
The assumption that internal inhibition dissipates in time
whereas excitation does not allowed for the deduction of a number of
experimental phenomena that Pavlov had demonstrated in his studies*
e.g.* spontaneous recovery* the different effects of massing and dis
tribution of trials on rate of conditioning and rate of extinction* etc*
Theories of the second class deny the necessity for assuming
an Independent inhibitory state and attempt to account for the decrement
In response in terms of a competing excitatory tendency to evoke an in
compatible response* Such theories are generally called counter-condi
tioning or interference theories. One of the major proponents of an
Interference theory is Guthrie (S»4) for whom extinction involves the
conditioning of a new response to the old stimulus* This new response
is incompatible with the old one and hence replaces or inhibits it.
The essential condition for producing such an event is failure of the
occurrence of the response in the presence of the stimulus. In order
to account for such phenomena as spontaneous recovery* Guthrie accepted
an hypothesis suggested by Winsor (19). Somewhat similar versions of
the interference theory have also been suggested by Culler (2) and
Wendt (16).
A third type of extinction theory is offered by Hull (©) •
Essentially this formulation is a combination of the two above-mentioned
3
kinds of concept ions* It is a two-factor theory assuming, on the one
hand, a process or state, reactive inhibition £%) * which is similar
in its behavioral properties to Pavlov’s internal Inhibition# and, on
the other hand, the building up of a competing response tendency*
Besetive inhibition (I#) in this formulation is defined as
a function of the amount of work required in the performance of the
response* It Is a hypothetical state which is assumed to accumulate
with the making of each response and dissipate in the interval between
responses* The presence or absence of the reinforcing stimulus is ir
relevant to the growth of reactive inhibition* The only reason that
the presence of the reinforcing stimulus leads to positive increments
in response strength is that increments of haulf strength resulting
from reinforcement are sufficient to offset increments of inhibition re
sulting from responding* Since primary reinforcement is absent during
extinction# increments of inhibition exceed those of habit strength
and a decrement la response strength is observed* like Pavlov# Hull’s
theory is also able to account for a wide range of extinction phenomena*
The second component of Hull’s theory is similar to the com
peting response hypothesis* Starting from the assumption the (Ijj) leads
to a primary negative motivational state, a need for rest, Hull postu
lates that cessation of the response which is responsible for inhibition
results in a reduction in the strength of the motivational state and
consequently an increment in the tendency of "not responding," which is
in competition with the original conditioned response.
4
The experimental literature relevant to various theories
is meager and, for the nost part, equivocal. Th© inhibition theory of
Pavlov and the two-factor theory of Hull have a certain advantage over
the interference theory in that they were specifically formulated with
a view to handling the various phenomena in conditioning studies coming
under the heading of inhibition, e.g .» experimental extinction, disia-
hibition, spontaneous recovery, inhibition of conditioning, inhibition
of dolayi etc* The interference theorists have attempted to account
for these same findings without assuming mm® inhibitory concept such
as Pavlovas internal inhibition or Hull’s reactive inhibition (J^),
Dae experimental finding that has been cited frequently as
offering critical evidence with respect to the Interference theory is
that variation of the intertrial interval has opposite effects in ac
quisition and extinction, This, it is claimed, is contrary to the im
plications of the interference theory. Unfortunately, the proponents of
the interference theory have never been too specific as to what pre
cisely does go on during extinction. However, if on© accepts their
commonly stated view (Culler, Guthrie) that extinction does not differ
from learning but merely involves relearning a new incompatible response*
or, as is sometimes said, is merely counter conditioning, then it would
00m reasonable to conclude that such a theory would# other thing© being
equal, predict bnat variation of the intortrial interval would have
comparable effects on extinction and acquisition. The implication of
the inhibitory theories (both internal inhibition and reaetiv© inhibition)
