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ABSTRACT

THE INFLUENCE OF EFFORT—REQUIREMENT ON
PERFORMANCE DURING-ACQUISITION AND
EXTINCTION OF A RUNNING

RESPONSE

by Wanda R. Jagocki

Four different measures (mean reciprocal latency, mean
reciprocal running time, mean number of trials to extinction,
and mean number of trials to median latency of Trials 1-30
of extinction) were used to determine the influence of effort
requirement on performance during the acquisition and ex-
tinction of a running response. Effort requirement was
varied by having albino and grey hooded rats traverse a run-
way which was either in a horizontal position or tilted up
at an angle of 15°. Four groups of §s were used: .O-Or . ,
(low effort during acquisition and extinction)

15-15 (High effort during acquisition and extinction)

15-0 (High effort during acquisition, low effort during
extinction)

15-0-0 (High effort followed by low effort during
acquisition, low effort during extinction)

Each group contained 10 §s, five albinos and 5 grey hoods.
The results obtained were:

1. Significant differences between the two strains
were found with regard to running time and mean number of
trials to extinction. The albinos ran faster and had a

greater number of trails to extinction than the grey hoods.

Wanda R. Jagocki

2. No significant difference in the decrement from
the last 10 trials of acquisition to the first 10 trials
of extinction with regard to latency was found between
the 0-0 group and 15-15 group. However, the 15-15 group
ran significantly slower during the first 10 trials of
extenction than did the 0-0 group. The 0-0 group also had
significantly greater resistance to extinction than the
15-15 group as evidenced by the mean number of trials to
the extinction criterion, but not by the number of trials
to the median latency of Trials 1-30 during extinction.

3. The 15-0 group exhibited facilitation in running
time during extinction as compared to the 15-15 group.
However, the reverse relationship was observed with regard
to the latency measure, although the difference between the
two groups was not statistically significant. No signi-
ficant difference between the 15-0 and 15-15 groups was
found in the two measures of resistance to extinction.

A. The 15-0 group was observed to have a greater
decrement in latency and running time than the 0-0 group,
although not significantly greater. The 0-0 group also
exhibited a greater mean number of trials to extinction
than the 15-0 group. This difference approached being
statistically significant.

5. Facilitation in latency was shown by the 15-0-0
group during the final 10 trials of acquisition when the

effort requirement was reduced. Although facilitation

Wanda R. Jagocki

was observed in the running time measure, the increment
was not statistically significant.

6. The 15-0-0 group exhibited a significantly greater
increment in latency, when the effort requirement was re-
duced during acquisition, than that of the 15-15 plus 15-0
group. However, the reverse relationship was observed with
regard to the running time measure, although this difference
was not statistically significant.

7. The 0-0 group exhibited greater resistance to
extinction than the 15-0-0 group as measured by the mean
number of trials to extinction.

8. The possible interaction of frustration and
change in the stimulus situation in producing behavioral
contrast with regard to the running response is hypothe-

sized.

THE INFLUENCE OF EFFORT REQUIREMENT ON
PERFORMANCE DURING ACQUISITION AND
EXTINCTION OF A RUNNING

RESPONSE

By

Wanda R. Jagocki

A THESIS

Submitted to
Michigan State University
in partial fulfillment of the requirements
for the degree of

MASTER OF ARTS

Department of Psychology

196“

ACKNOWLEDGMENTS

I gratefully acknowledge the assistance of Dr. M. Ray
Denny in the formulation, execution, and interpretation of
this study. I also wish to thank the other members of my
committee, Drs. Paul Bakan and Terrence Allen, for their

contributions to this project.

11

TABLE OF CONTENTS

Page
ACKNOWLEDGMENT . . . . . . . . . . . . . 11
LIST OF TABLES . . . . . . . . . . . . . v
LIST OF FIGURES. . . . . . . . . . . . . Vi
Chapter

I. INTRODUCTION. 1
Hull . . . . 2
Mowrer and Jones (19A3) . . . . 2
Capehart, Viney and Hulicka (1958) . . A
Maatsch, Adelman and Denny (1954). 5
Weiss (1961). . . . . . . . 5
Applesweig (1951) . . . . . . . 8
Stanley and Aamodt (l95u) . . 9
Aiken (1957) . 9
Stachnik (1963).. . lO
Lawson and Brownstein (1957) . . l2
Jensen (1960) . . . 13
Resistance to Extinction. 1A
Latency . . . . 16
Running Time. . . . 17
II. METHOD. . . . . . . . . . . . . 19
Subjects . . . . . . . . . . . 19
Apparatus. . . . . . . . . . . 19
Procedure. . . . . . . . . . . 20
III. RESULTS . . . . . . . . . . . . 26
Mean Reciprocal Latencies . . . . . 26
Mean Reciprocal Running Times . . . . 30
Mean Number of Trials to Extinction . . 3A

Mean Number of Trials to Reach the

Median Latency of Trials 1-30 of
Extinction (7.5 sec.) . . . . . . 37
IV. DISCUSSION AND CONCLUSION . . . . . . 38
Mean Reciprocal Latencies . . . . . 38

iii

REFERENCES.
APPENDICES.

Mean Reciprocal Running Times
Mean Number of Trials to Extinction
Mean Number of Trials to Reach the

Median Latency of Trials 1- 30 of

Extinction
Conclusions

iv

Page

HO
HA

A6
A8

50
52

Table

LIST OF TABLES

Summary of procedure used for the four
experimental groups

Mean decrements in mean reciprocal latencies
from trials 51—60 of acquisition to trials
l-lO of extinction of the four groups

Summary of t-tests made on increments in mean
reciprocal latencies from trials 41-50 to
trials 51-60 of acquisition . .

Mean decrements in mean reciprocal running
times from trials 51- 60 of acquisition to
trials 1- 10 of extinction for the four
groups and two strains . .

Summary of t-tests made on decrements in
mean reciprocal running times from trials
51-60 of acquisition to trials 1—10 of
extinction . . . . . . . .

Mean number of trials to extinction for the
four groups and two strains

Summary of t-tests made between mean number
of trials to extinction of groups within
each strain and the combined probabilities
of these comparisons. . . . .

Mean number of trials to reach latency of 7.5
sec. during trials l-3O of extinction for
the two strains and four groups .

Page

21

27

28

31

32

3A

35

37

LIST OF FIGURES

Figure Page
1. Floor plan of apparatus . . . . . . . . 22
2. Apparatus tilted up at an angle of 15° . . . 22

vi

CHAPTER I
INTRODUCTION

One independent variable which is often cited for
its importance in influencing the strength of a response,
usually measured in terms of resistance of the response
to extinction, is that of effort. It has generally been
assumed that if it takes an organism more work to make a
particular response, the organism is going to stop making
that response, once reinforcement is omitted, sooner than
an organism that doesn't have to do quite as much work to
make a similar type of response. However, attempts to
demonstrate this experimentally have been inconclusive.
The majority of the studies concerned with the role of
effort in the resistance to extinction of a response have
varied the amount of effort required to make a response
by varying the weightings of the bar in a Skinner box
apparatus. A general criticism which can be leveled at
all these studies is that the animals must initially be
trained on a light bar before any training on a heavy bar
is possible. This initial training may be more of a
factor in determining the greater resistance to extinction
of animals trained and extinguished on light bars than the
amount of effort required to make the response.

1

Hull

 

The first formal statement of the supposed relation-
ship between effortfulness of the response and resistance
to extinction was put forth by Hull. Within the framework
of Hullian theory, the resistance to extinction of a
response is held to be an inverse linear function of the
amount of effort or work involved in making a response.
As the amountof work required to make a response increases,
reactive inhibition (Ir) also increases. This reactive
inhibition is conceptualized as a negative-type of drive.
Dissipation of Ir brought about by cessation of the response,
is considered to be reinforcing, and thereby strengthens
this habit of "not-responding."

Whenever any reaction is evoked in an organism

there is left a condition or state which acts as a

primary negative motivation in that it has an innate
capacity to produce a cessation of the activity which

produced the state. (Hull, 19u3’ p. 278)

It is the accumulation of more Ir’ when greater effort is
required to make the response, which leads to faster

extinction of the response.

Mowrer and Jonesg(l9A3)
As evidence for the relationship between effortfulness
of the response and resistance to extinction, Hull cited a
study by Mowrer and Jones in which the amount of work
involved in making a bar press response was varied by chang-

ing the bar weightings. In this study, the acquisition

conditions were the same for all animals. At the end of
training, each S had made 180 responses on a bar weighted
with 5 gm., 20 responses on a bar weighted with 30 gm.,
20 responses on a bar weighted with 55 gm., and 60 re-
sponses on a bar weighted with 80 gm. The §s were then
divided into three groups. One group was extinguished on
a 5 gm. bar, one on a 42.5 gm. bar,‘and the last group on
an 80 gm. bar. The mean number of responses made during
extinction for the group extinguished on the 5 gm. bar was
350.3, for the group extinguished on the 42.5 gm. bar

the mean was 248.4, and for the group extinguished on the
80 gm. bar the mean was 110.7 responses. Thus, Mowrer
and Jones concluded that ". . . effortfulness of the task
is inversely related to the number of extinction re-
sponses . . ." (Mowrer and Jones, 1943, p. 374).

The most obvious flaw of this study lies in the lack
of control of the habit strengths of the various responses.
A total of l80 reinforced reSponses were made on the 5 gm.
bar as compared to 60 reinforced responses on the 80 gm.
bar. It is more likely that differences in the number of
reinforced responses, i.e., habit strength, rather than
the effort variable can account for the Mowrer and Jones

results.

Capehart, Viney and Hulicka (1958)

 

In an attempt to control for unequal training at the
various bar loadings, Capehart, Viney and Hulicka gave
each of their rats 30 reinforcements at each of three bar
weightings. The bar loadings were scheduled by day in the
order: 5 gm., 40 gm., 70 gm., 5 gm., 70 gmx, 40 gm. Upon
completion of acquisition, the §s were divided into three
groups and extinguished on a 5 gm., 40 gm., or 70 gm. bar.
The 5 gm. group was found to bermost resistant to extinc-
tion while the 70 gm. group was least resistant to extinc—
tion. The investigators concluded that "the number of
responses to extinction is a function of the effort required
to make the response" (Capehart, Viney and Hulicka, 1958,
p. 507).

However, if one considers the point made in the
Maatsch, Adelman and Denny study (1954), the Capehart,
Viney and Hulicka design also failed to control for differ-
ences in habit strength. Maatsch, Adelman and Denny main-
tain that ". . . if trained to push a heavy bar, rats can
easily push all lighter bars, but if trained upon light

bars, they have difficulty in pushing heavier bars"

 

(Maatsch, Adelman and Denny, 1954, p. 47). Therefore, in
[the Capehart, Viney and Hulicka study, when 30 responses
on a 70 gm. bar were reinforced, 30 responses on a 40 gm.,
and 30 responses on a 5 gm. bar, were simultaneously being

reinforced. If such an assumption is made, then each S was

actually reinforced 90 times for a 5 gm. bar press (30 on
5 gm., 30 on 40 gm., and 30 on 70 gm.), but only 60 times
for a 40 gm. bar press (30 on 40 gm., and 30 on 70 gm.),
and only 30 times for a 70 gm. press (30 on 70 gm.).

Maatsch, Adelman and Denny (1954)

In the Maatsch, Adelman and Denny study, after
preliminary shaping on a 5 gm. and then on a 40 gm. bar,
the §§_were divided into three groups. In one group, the
bar was loaded at 5 gm., in the second at 40 gm., and in
the last at 80 gm., The animals were given a total of 25
reinforcements, and were then extinguished on the same

bar weightings as they had been trained on. 'The results

indicated that there was "no relationship between the amount

of effort required to make a response and the resistance

to extinction of that response" (Maatsch, Adelman and Denny,

195”: pp° ”9-50)-

Weiss (1961)

 

In the studies previously discussed, the rate of

bar-pressing was the dependent variable. Weiss gave discrete

trials in a bar-pressing situation in order to measure
latency rather than rate of pressing. He also varied the
length of a behavior chain by having the rats make 1, 4 or

8 presses prior to delivery of reinforcement and removal

of the bar. Using a complete factorial design, Weiss varied

work at five levels (15 gm., 50 gm., 100 gm., 150 gm.,

 

and 200 gm. bar loadings) and length of behavior chain at
three levels (1, 4 and 8 presses). A trial began when the
bar was inserted and ended when the respective number of
presses had been made, and the bar removed. After 96
reinforced acquisition trials, extinction was run and
resistance to extinction determined. Although Weiss

used a variety of speed measures (e.g., "starting speed" -
speed of the first press in the chain), when the "total
time," i.e., the time from introduction of the bar to
delivery of reward, was analyzed there was no significant
effect for either length of behavior chain or effort
requirement. Likewise, there were no significant differ-
ences between the work groups in resistance to extinction.
These results would tend to support the Maatsch, Adelman
and Denny findings for even larger bar loadings.

In general, it has been noted that if rats are trained
under high effort requirement and extinguished under low
effort requirement, they tend to exhibit greater resistance
to extinction than animals trained and extinguished under
low effort requirement. Although only Stachnik, (1963)
actually found statistically significant differences between
groups of animals trained and extinguished light, and
those trained heavy and extinguished light, it is a finding
to which theorists have attempted to address themselves.
The available theories have difficulty in explaining such

results. According to the generalization decrement

hypothesis, greater resistance to extinction is found as
the similarity between the acquisition and extinction
conditions increases. Therefore, it would be expected
that animals trained and extinguished under low effort,
iii- greater similarity in acquisition and extinction
conditions, would exhibit greater resistance to extinction
than animals trained under high effort and extinguished
under low effort, i.e., little similarity between acquisi-
tion and extinction conditions. The reverse appears to
be the case. It might be argued, however, that changes
in the loading of the bar is not a sufficient cue to
enable discrimination between the acquisition and extinc-
tion conditions. Taking a Hullian viewpoint, one might
argue that greater habit strength results from making a
more effortful response during training, and this would
account for the greater resistance to extinction of the
high effort animals when switched to low effort during
extinction. However, an alternative hypothesis has
been put forth by Stachnik who postulates that the facili-
tation observed is actually due to a contrast effect.
Among the studies which have varied effort require—
ment during acquisition and extinction are those by

Applezweig; Stanely and Aamodt; Aiken; and Stachnik.

Applezweig (1951)

Applezweig trained five groups of rats to press
bars requiring 10, 20, 30, 40 or 50 gm. of effort to ob-
tain water. After 50 reinforced trials the §s were divided
into five sub-groups, each of which was extinguished at
one of the five effort levels, e.g., (acquisition) 10-10
(extinction), 10-20, . . . 10-50, 20-10, 20-20, . . .
20-50, 30-10, etc. Applezweig concluded that "when habit
strength is constant, the more effortful the performance
of a task after reinforcement has been removed, the more
rapidly will extinction occur" (Applezweig, l95l, p. 235).
In other words, rats trained light and extinguished heavy
show faster extinction. It was also asserted that "the
more effortful the performance of a task, the better will
it be learned (the greater will be its response potential)"
(Applezweig, 1951, p. 235). A questionable assumption
made in this study is that rats trained on light bars
press heavier bars as easily as rats trained on heavy
bars press lighter bars. Referring back to the point made
by Maatsch, Adelman and Denny, i.e., rats trained on heavy
bars can easily push all lighter bars while rats trained
on light bars have difficulty in pushing heavier bars,
this assumption does not seem tenable. In addition,
Applezweig discarded 79 of an original 179 animals on the

basis of a weak initial tendency to press heavy bars. Thus,

most of the 79 discarded animals were of the heavy bar
loading groups and hence non—random selection of Se in

some groups resulted.

Stanley and Aamodt (1954)

 

Stanley and Aamodt trained half of their §s under a
50 gm. bar loading and the other half under a 100 gm.
bar loading. At the end of training, half of each acquisi-
tion group was extinguished under the 50 gm. force require-
ment, and half under the 100 gm. force requirement,
resulting in a total of four groups: (training) 50-50
(extinction), 100-50, 50-100, and 100-100. The mean number
of bar presses made during the two days of extinction was
in the order: 100-50 > 50-50 > 50-100 > 100-100. How-
ever, none of these differences were statistically signifi-

cant.

Aiken (1957)—

 

Aiken employed a panel-pushing task in which the
rats were reqired to swing a door forward in order to secure
food. The amount of force needed to push the door forward
was 32 gm. for the high effort group and 5 gm. for the low;
effort group. After a total of 60 acquisition trials, the
§S were fractionated into four extinction conditions result-
ing in a total of four groups: High-High, High-Low, Low-
High and Low-Low. Although the differences in the mean

number of trials to extinction were not statistically

10

significant, Aiken concluded that there "was increased
resistance to extinction following high-effort during
learning, and reduced resistance to extinction with high
effort during extinction trials . . ." (Aiken, 1957, p. 51).

The means were in the order : H—L > H—H > L-L > L-H.

Stachnik (1963)

 

Stachnik employed a bar-press situation in an
attempt to determine the effect of effort requirement on
resistance to extinction when habit strength was held

constant. A total of seven groups were used:

 

 

No. and Bar-Loading Bar-Loading

Group of Reinforcement During Extinction

L L 200 200 on 5 gm. 5 gm.

H H 120 80 on graduated loadings, 80 gm.
150 on 80 gm.

H H 200 80 on graduated loadings, 80 gm.
200 on 80 gm.

H L 120 l 80 on graduated loadings 5 gm.
120 on 80 gm.

HL L 120 50 on graduated loadings, 5 gm.
120 on 80 gm., 30 on 5 gm.

LMH L 90 30 on 5 gm., 30 on 40 gm., 5 gm.
30 on 70 gm.

LMH H 90 30 on 5 gm., 30 on 40 gm., 70 gm.
30 on 70 gm.

(Stachnik, 1963, p. 13).

 

11

Significant differences were found in the following

comparisons of mean number of responses to extinction: -

LMH L 90 (I: 97.4) > LMH H 90 (i = 32.3)
H H 120 (1?: 110.1) > LMH H 90 (I: 32.3)
H L 120 (X'= 310.8) > L L 200 (1?: 155.7)
H L 120 (1? = 310.8) > HL L 120 (55: 193.0)

The significant difference between LMH L 90 and
LMH H 90 supports the criticism of unequal habit strengths
in the Capehart, Viney and Hulicka study. The group
extinguished light made three times as many responses as
the group extinguished heavy.

The assumption that rats trained on light bars
depress heavier bars with equal facility is rejected on
the basis of the H H 120 group making significantly more
responses than the LMH H 90 group.

The fact that the mean number of responses of the
H L 120 group was significantly greater than that of the
LL 200 group leads to the conclusion that "animals
trained on a heavy bar and extinguished on a light bar show
a marked facilitation" (Stachnik, 1963, p. 30). And
further "the facilitation is the result of a contrast in
stimulation since the insertion of light—bar reinforce-
ments Just prior to extinction essentially eliminates it"
(Stachnik, 1963, p. 30). This conclusion is made on the
basis of the greater number of responses made during

extinction by the H L 120 group than by the HL L 120 group.

12

Behavior contrast refers to "the change in the rate of
responding during the presentation of one stimulus . . . in
a direction away from the rate of responding generated
during the presentation of the other stimulus" (Reynolds,
1961, p. 57). As applied to the situation used in
Stachnik's study, the change in the cues for the high
effort group when switched to low effort during extinc-
tion, elicited a greater number of responses during
extinction for this group than for the group which had

these cues changed prior to extinction.

Lawson and Brownstein (1951)

An attempt was made by Lawson and Brownstein to vary
effort requirement in a non-bar press situation. They
trained rats to "traverse a runway containing three
hurdles, which for half the §s were removed during extinc-
tion. Removal of the hurdles was presumed to reduce
the effortfulness of response and simultaneously increase
the discriminability of training and extinction conditions"
(Lawson and Brownstein, 1957, p- 23). The three hurdles,
about two inches high, were spaced about one foot apart.
Following training, the §s were divided into two groups;
one which had the food and food cup removed, while the
other group had the hurdles removed as well as the food
and food'cup. "All §s were given massed extinction trials
to a criterion of two successive failures to enter the

end-box within 2 min. after the starting door was raised"

13

(Lawson and Brownstein, 1957, p. 124). It was found that
"the §s for which the hurdles remained in place showed
significantly greater resistance to extinction, although
they were presumably expending more effort per trial"
(Lawson and Brownstein, 1957, p. 125). These results

can best be explained in terms of the generalization
decrement hypothesis. The §s for whom the hurdles re-
mained in place had greater similarity between the acquisi-
tion and extinction conditions than did the SS for whom the
hurdles were removed. The greater the similarity between
the training and extinction conditions, the greater the

resistance to extinction.

Jensen (1960)

Jensen also employed a non-bar press situation in
studying the influence of the effortfulness of a response
upon acquisition. It was asserted that "any variable that
increases the vigor of a response also increases the
effortfulness of the response (the greater the vigor, the
greater the kinetic energy gained, hence the greater the
effort expended)" (Jensen, 1960, p. 268). The levels of
effort-requirement were obtained by varying the angle of
incline of the runway of a T-maze. 0n the first experi-
mental day (Day 8) each of the §s received 30 acquisition
trials. On Trials 1-5, all §s were run with the maze in a
horizontal position; on the remaining 25 trials "the maze

was tilted or not tilted depending upon which condition

14

§_was in" (Jensen, 1960, p. 263). During the second

experimental day (Day 9), all §s were given 15 acquistion

trials, under the same effort requirement as they had

been run under on the first experimental day, followed by

15 acquisition trials with the maze in a horizontal

position. This procedure was based upon the considera-

tion that "if the effort variable had caused depressed

acquisition curves for the high-effort groups, then

the acquisition curves of these groups should have

approached the curve of the low-effort (horizontal) group

during the last 15 trials of Day 9" (Jensen, 1960, p. 263).

Jensen concluded that "the effort-requirement variable

gave no suggestion of a main effect" (Jensen, 1960, p. 268).
In light of the findings of the experiments in which

the barepress situation was used, Stachnik's in particular,

it was the purposerof the present study to ascertain

whether similar phenomena would occur in a situation

similar to that used by Jensen. An additional purpose

was to see whether the results could best be predicted by

a Hullian inhibition theory approach or by the generali-

zation decrement hypothesis.

Resistance to Extinction
The major comparisons, with regard to resistance to
extinction, which the present study intended to investigate

were:

15

1. Will a group trained and extinguished on a
horizontal runway (0-0 group, i.e., low effort requirement)
show greater resistance to extinction than a group trained
and extinguished on a runway which is inclined at a 15°
angle (15-15 group, i.e., high effort requirement)?
According to Hullian inhibition theory, the 15-15 group
should extinguish significantly faster than the 0-0 group.
The 15-15 group presumably builds up more Ir than the 0-0
group leading to a depression of performance. However,
according to the generalization decrement hypothesis,
there should be no significant difference between the
groups, since the acquisition and extinction conditions
are equally similar to each group.

2. Will a group trained on a runway which is inclined
at a 15° angle and extinguished on a horizontal runway
(15-0 group, i.e., high effort requirement during training -
low effort requirement during extinction) show facilitation,
i.e., increased resistance to extinction, as compared to
the 15-15 group? Using a Hullian orientation, one might
argue that the response potential of a high effort habit
is greater than that of a low effort habit, thus account-
ing for the observed facilitation when the high effort
group is switched to low effort in extinction. However,
according to the generalization decrement hypothesis, the

15-0 group should show more rapid extinction of the response

16

since there is very little similarity between the training
and extinction conditions.

3. If facilitation is exhibited by the 15-0 group,
could such a result be caused by a behavioral contrast
effect? If this facilitation is due to a contrast effect,
could it be eliminated if the final 10 training trials
were run on a horizontal runway rather than on a runway
inclined at 15°, and extinction was on the horizontal
runway (15-0-0 group)? According to inhibition theory,
this group should still exhibit the facilitation since it
is still required to make a less effortful response during
extinction, and in addition any depression of per-
formance should be dissipated more quickly due to the
insertion of the low effort trials prior to extinction
The generalization decrement hypothesis would predict
greater resistance to extinction for this group than for
the 15-0 group since the similarity between the final
10 trials of acquisition and extinction would be greater

for the 15-0-0 group than for the 15-0 group.

Latency
With regard to latency, i.e., time taken by S to leave

the start-box once the Start-box door has been raised,
the questions are:
1. Will the 15-15 group show a significantly greater

decrement in latency than the 0-0 group as hypothesized by

17

inhibition theory, or will the difference between the
decrements of the two groups be non-significant as hypo-
thesized by the generalization decrement position?

2. Will the 15-0 group exhibit facilitation as
compared to the 0-0 and 15-15 groups? If it does
exhibit facilitation, this would be indicated by its
having less of a decrement in latency than either the
0-0 or 15-15 group. If the generalization decrement
hypothesis is supported, the 15-0 group should exhibit
a greater decrement than either the 0-0 or 15-15 group.

3. Will the 15-0-0 group exhibit a greater in-
crement in latency on the final 10 trials of acquisition
than that of the 15-15 and 15-0 groups? If a contrast
effect is operating, this would be exhibited by a signifi-
cantly greater increment in latency for the 15-0-0 group

from Trials 41-50 to Trials 51-60 of acquisition.

Running Time

With regard to running time, i.e., the time it takes
the animal to run a distance of 36 in., the questions
are:

1. Will the 15-15 group show a significantly
greater decrement in running time than the 0-0 group as
hypothesized by inhibition theory, or will there be no
difference between the decrements of the two groups as

hypothesized by the generalization decrement position?

18

2. Will there be any facilitation exhibited by the
15-0 group as indicated by less of a decrement in running
time as compared to the 0-0 and 15-15 groups, or will
this group exhibit a greater decrement as the generali-
zation decrement hypothesis predicts?

3. If facilitation is exhibited by the 15-0 group,
will it also be exhibited by the 15-0-0 group during
the final 10 trials of acquisition?

CHAPTER II

METHOD

Subjects
A total of 40 male rats, 20 albino (Holtzman) and

20 grey-hooded, were used as §§~ The §§ were approxi-
mately 150 days old at the start of the experiment, and
were obtained from the colony maintained by the Psychology
Department of Michigan State University. The animals were
housed in individual cages. The S§_were assigned by a
table of random numbers to one of the four experimental
.groups. Each group contained 10 §§: five albinos and five
grey hoods. The order of running strains within a group
was not randomized, rather the first five animals run in

each group were albinos, and second five were grey-hoods.

Apparatus

 

A floor-plan of the apparatus used is shown in
Fig. l. The apparatus was a 48 in. long runway, 8 in.
wide, and 5 in. deep. The runway was made of 3/4 in.
thick unpainted pine, and was covered with wire mesh.

The start box and goal box were 12 in. long, 6 in. wide,

and 4 in. deep, and were made of clear plexiglass with a
hinged top. A photoelectric cell was located at a dis-

tance of 6 in. from the start box (PECl), and another
19

20

cell was at a distance of 6 in. from the goal box (PECZ).
A Standard Electirc Timer was started when S passed PEC1

and was stopped when S passed PECZ, giving the time it
took S to run a distance of 36 in. Guillotine doors were

located outside of the start and goal boxes. A stopwatch
was used to measure latency, i.e., the time it took S to
leave the start box once the door had been raised. A
shaded 75 watt bulb was suspended above the center of the
apparatus yielding relatively homogeneous lighting.

The runway was attached to the start and goal boxes
with hinges which enabled the inclination of the runway
to an angle of 15°. The start and goal boxes remained

horizontal when the runway was tilted up (Fig. 2).

Procedure

Table 1 summarizes the procedure used for the four
groups. The effort requirement is defined in terms of
the angle of incline of the runway, i.e., high effort
refers to running up an incline of 15° and low effort
refers to running an incline of 0° (horizontal).

Fourteen days prior to the start of the experimental
procedure, the §§ were placed upon a deprivation schedule
in which they were allowed to eat ad lib for one hour per
day. Water was supplied in the home cages at all times.
All §§ were handled for approximately 5 minutes per day
during these 14 pre-experimental days. Two days before

the start of the experiment, the §§ were allowed to explore

21

the runway (which was in a horizontal position) for 5

min. The animals were also given training in eating two
45 mg. pellets of food from the glass food cup while being
enclosed in the goal box. The same procedure was followed
on the day before the start of the experimental procedure.
The §§ were under approximately 22 hr. deprivation during
the experiment.

Table l.--Summary of procedure used for the four experimental
groups.

W
, Angle of Incline of Runway

 

 

Trials 0-0 15-15 15-0 7 15-0-0
Acquisition
1-10 0 O O 0
11-50 0 15 15 15
51-60 0 15 15 O
Extinction 0 15 0 0

 

The procedure employed in running the §§ during the
experiment was as follows: After being brought into the
experimental room, all §§ were given a 5 min. period in which
to adapt to the surroundings before the actual running was
begun. At the end of the 5 min. adaptation period, S
picked the first animal up and placed it in the start box.
After traversing the runway and entering the goal box, the
goal box door was closed, and S remained in the goal 7

box for approximately 10 sec. During this time S noted the

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23

latency and running time measures. The S was removed from
the goal box and replaced in its home cage. The second
animal in the block being run was then taken from its cage
and placed in the start box, and the entire procedure re-
peated until all Sg_in the block had run a total of 10
trials (or 20 during extinction) in rotation. After the
animals had been run, they were returned to the room in
which they were housed and were fed.

Throughout acquisition and extinction the ITI for
an individual S was the time it took the other §§ in the
block to run a particular trial. Thus the ITI varied
during the course of the experiment, generally becoming
shorter during the latter trials of acquisition and leng-
thening during extinction. It should also be noted that
the first 12 animals run were run in two blocks of six
each, one block being started a day earlier than the
other. However, due to the limitations of time, it was
found to be more practical to run the animals in blocks of
four, with one block starting four days prior to the second
block, and the difference in procedure did not appear to
affect the data. The order in which the §§ within a block
were run on each day was determined by a random number table.
All §§ ran a total of 10 trials per day during training, and
received reinforcement (two 45 mg. pellets of food) on every
trial. On Day 1, all S§.ran the initial 10 acquisition

trials with the runway in a horizontal position (0° angle of

24

incline). On Days 2-6 the §§ were run according to their

assigned groups. Extinction began on Day 7, and con-

sisted of 20 trials per day. The §§ were run until they

I

reached a criterion of two consecutive trials in which

latency plus running time was at least 120 sec., or for

80 trials if they failed to reach criterion.

15-15

15-0

The groups employed were as follows:

(Low effort during acquisition and extinction)
This group received a total of 60 training trials
with the runway in a horizontal position (0° angle
of incline), and was extinguished with the alley in
the horizontal position.

(High effort during acquisition and extinction)
This group received 10 training trials with the
runway in the horizontal position, 50 training
trials with the runway inclined at an angle of
15°, and was extinguished with the runway inclined
at an angle of 15°.

(High effort during acquisition and low effort
during extinction)

This group received 10 training trials with the
runway in the horizontal position, 50 training
trials with the runway inclined at an angle of 15°,
and was extinguished with the runway in the hori-

zontal position.

25

15-0-0 (High effort followed by low effort during acquisi-
tion and low effort during extinction)

This group received 10 training trials with the
runway in the horizontal position, 40 training
trials with the runway inclined at an angle of
15°. 10 training trials with the runway in the
horizontal position, and was extinguished with

runway in the horizontal position.

CHAPTER III
RESULTS

All latency and running time measures were con-
verted to reciprocals to meet the assumptions of the
analysis of variance (Edwards, 1962). The mean of the
reciprocals of every 10 trials was computed for each
S, and was used as a raw score in analyzing the results.
For example, if a reference is made to the mean recipro-
cal latency of Trials 1-10 of acquisition this refers
to the mean of the reciprocals of the latencies recorded

on Trials 1-10 of acquisition for a particular S.

Mean Reciprocal Latencies

Latency was defined as the time it took S to leave
the start box once the start box door had been raised.
Table I in the Appendix shows the mean reciprocal laten-
cies of the four groups during acquisition and extinction
(each entry is the grand mean of the mean reciprocal laten-
cies of the 10 §§ in each group).

A 4 x 2 analysis of variance was made on the mean
reciprocal latencies of Trials 1-10 of acquisition to
determine if any differences existed between the four
groups and/or two strains (Table II--Appendix). Neither

the main effects nor the interaction were found to be

26

27

significant. Since there was no difference between al-
binos and grey hoods, all subsequent comparisons were made
without analyzing any possible strain differences.

A simple analysis of variance was run on the mean
reciprocal latencies of Trials 51-60 of acquisition for
the four groups (Table III--Appendix). The analysis
yielded no significant differences among the groups in
mean reciprocal latencies of the final 10 trials of ac-
quisition.

In order to make the various comparisons outlined
in the Introduction, difference scores were used in the
remaining analyses of the latency measures. It was rea-
soned that a difference score, which was computed by
subtracting the mean reciprocal latency of Trials 1-10
of extinction from the mean reciprocal latency of Trials
51-60 of acquisition for each S, would best represent
the amount of decrement in latency from the final 10
trials of acquisition to the first 10 trials of extinc-
tion. These decrements appear in Table 2.

Table 2.--Mean decrements in mean reciprocal latencies

from trials 51-60 of acquisition to trials 1-10 of ex-
tinction of the four groups

 

 

—v -—y W

0-0 ‘ 15-15 . 15-0 15-0-0

 

y-

.488 .496 .498 .698

 

28

An analysis of variance made on these decrements indicated
that the differences among the four groups were not statis-
tically significant (Table IV--Appendix).

The measure used to indicate the amount of incre-
ment in latency was computed by subtracting the mean re-
ciprocal latency of Trials 41-50 of acquisition from the
mean reciprocal latency of Trials 51-60 of acquisition.
The comparisons made on the increments in mean recipro-
cal latencies on the final trials of acquisition are pre-
sented in Table 3.

Table 3.--Summary of t-tests made on increments in mean

reciprocal latencies from trials 41-50 to trials 51-60
of acquisition

W

 

Comparison Mean p

15-0-0 (Trials 51-60) 1.806 AL.Ol(2-tailed)
(Trials 41-50) 1.566

15-0-0> .240 A.Ol(l-tailed)

15-15+15-0 .158

 

A t-test made on the difference in mean reciprocal laten-
cies from Trials 41-50 to Trials 51-60 of acquisition for
the 10 §1 of the 15-0-0 group yielded a statistically sig-
nificant increment. On Trials 1-50 of acquisition, the
15-15, 15-0, and 15-0-0 groups were under the same experi-
mental procedure. The difference in training occurred on
Trials 51-60 when the 15-0-0 group ran these 10 trials on

the horizontal runway while the other two groups continued

29

to run on the runway inclined at an angle of 15°. If the
15-0-0 group exhibited facilitation due to the hypothe-
sized contrast in stimulation it was held that this would
be manifested in a greater increment for this group as
compared to the pooled increment of the other two groups
(15-15 and 15-0). It was found that the 15-0-0 group

did show a significantly greater increment than that of
of the 15-15 plus 15-0 group. In other words, when the
runway was lowered to the horizontal position during the
final 10 trials of acquisition the animals left the start
box significantly faster than those animals which continued
to run the inclined runway.

The following is a summary of the results obtained
with regard to mean reciprocal latenCies:

1. No significant difference was found between the
albino and grey hooded animals in mean reciprocal latencies
on Trials l-10 of acquisition.

2. No significant difference was found in the mean
reciprocal latencies of Trials 51-60 of acquisition among
the four groups.

3. No significant difference was found among the
four groups in the decrement in mean reciprocal latencies
from the last 10 trials of acquisition to the first 10
trials of extinction, although the 15-0-0 group did exhibit

the greatest decrement.

30

4. A significant increment was found in mean recipro-
cal latency from Trials 41-50 to Trials 51-60 of acquisi-
tion for the 15-0-0 group.

5. The increment in mean reciprocal latency from
Trials 41-50 to Trials 51-60 of acquisition of the 15-0-0
group was significantly greater than the increment of the

15-15 plus 15-0 group.

Mean Reciprocal Running Times

Running time refers to the time it took S to traverse
a distance of 36 in. (the distance from PEC1 to PECZ).
Table V in the Appendix shows the mean reciprocal running
times of the two strains (i.e., albino and grey hooded)
within each of the four groups during acquisition and ex-
tinction (each entry is the grand mean of the mean reci-
procal running times of the 5 §§ of each strain in each
group).

A 4 x 2 analysis of variance was made on the mean
reciprocal running times of Trials 1-10 of acquisition to
determine if any differences existed between the four
groups and/or two strains. A significant difference be-
tween the two strains (p<fi.005), but not between groups,
was found (Table VI--Appendix). Because of the signifi-
cant difference found between strains all subsequent com-
parisons included this organismic variable.

A similar analysis of variance made on the mean

reciprocal running times of Trials 51—60 of acquisition

31

for the four groups and two strains again yielded a sig-
nificant difference between strains but not among the
groups (Table VII--Appendix).

In order to make the various comparisons outlined
in the Introduction, difference scores, which were de—
scribed with regard to mean reciprocal latencies, were
used to examine the decrements in mean reciprocal running
times from Trials 51-60 of acquisition to Trials 1-10 of
extinction. The mean decrements for each group appear
in Table 4.

Table 4.--Mean decrements in mean reciprocal running times

from trials 51-60 of acquisition to trials 1-10 of extinc-
tion for the four groups and two strains

 

 

 

 

0-0 15—15 15-0 15-0-0
Albino .177 .471 .250 .270
Grey Hooded .122 .347 .150 .291
Mean of Strains .149 .409 .200 .280

 

An analysis of variance of the decrements yielded a
significant main effect of Groups (p44.01), but neither
the main effect of Strains nor the interaction of S x G
were significant. This analysis appears in Table VIII in
the Appendix.

Because a significant difference among groups was
found, a series of t-tests were run in accordance with

the questions raised in the Introduction. The two strains

32

were not analyzed independently because of the non-signifi-
cant difference found in the analysis of variance. The
various comparisons made are summarized in Table 5.

Table 5.-- Summary of t-tests made on decrements in mean

reciprocal running times from trials 51-60 of acquisition
to trials 1-10 of extinction

 

 

Comparison Mean p

15-15> .409 4.005 (l-tailed)
0-0 .149

15-15>' .409 <:.01 (1-tailed)
15-0 .200

0-0 - .149 4 .50 (2-tailed)
15-0 .200

15-o-o> .280 21.150 (l-tailed)
15-0 .200

 

As can be seen from Table 5, the 15-15 group exhibited a
significantly greater decrement in running time than both
the 0-0 group and the 15-0 group. However, there was no
difference in the decrements of the 0-0 and 15-0 groups.
There was also no significant difference in the decre-
ments of the 15-0-0 and 15-0 groups.

A t-test was made on the difference in mean recipro-
cal running times from Trials 41-50 to Trials 51-60 of
acquisition for the 15-0-0 group. No significant incre-
ment in mean reciprocal running time was found for the
15-0-0 group. In comparing the increment of the 15-0-0

group to that of the 15-15 plus 15-0 group it was noted

33

that the increment of the 15-15 plus 15-0 group was
actually greater than that of the 15-0-0 group. However,
this difference was not statistically significant. The
results of these two t-tests appear in Table IX in the
Appendix.

The following is a summary of the results obtained
with regard to mean reciprocal running times:

1. A significant difference was found between the
albino and grey hooded animals on Trials 1-10 of acquisi-
tion as well as on Trials 51-60 of acquisition.

2. No significant difference was found in the mean
reciprocal running times of Trials 51-60 of acquisition a-
mong the four groups.

3. The 15-15 group had a significantly greater
decrement in mean reciprocal running time from the last
10 trials of acquisition to the first 10 trials of extinc—
tion than the 0-0 group.

4. The 15-15 group also had a significantly
greater decrement than the 15-0 group.

5. No significant difference in decrements was
foudn between the 0-0 group and the 15-0 group.

6. No significant increment in mean reciprocal
running time from Trials 41-50 to Trials 51-60 of acquisi-
tion was found for the 15-0-0 group.

7. This increment was less than the increment of the

15-15 plus 15-0 group although not significantly less.

34

Mean Number of Trials to Extinction
The criterion for extinction was two consecutive
trials in which latency plus running time was at least
120 sec. If this criterion was not met, extinction was
carried out for a total of 80 trials.
The swan number of trials to extinction for the
four groups and two strains appears in Table 6.

Table 6.--Mean number of trials to extinction for the
four groups and two strains

 

 

 

0-0 15-15 15-0 15-0-0
Albino 70.4 63.2 62.0 48.4
Grey Hooded 27.8 12.6 19.8 17.4

 

A 4 x 2 analysis of variance of the number of
trials to extinction for the four groups and two strains
appears in Table X in the Appendix. Only the main effect
of Strains was significant (p41.005).

Because of the tremendous difference between strains
in the number of trials to extinction, comparisons were
made between the groups within each strain. Since the
levels of significance thus obtained were independent,

they were then combined according to the formula: p =

(P1 + P2)2
2

ticular group comparison. The various comparisons made

 

to yield the significance level of any par-

appear in Table 7.

35

Table 7.--Summary of t-tests made between mean number of
trials to extinction of groups within each strain and the
combined probabilities of these comparisons

 

 

 

 

 

 

 

Comparison Mean p

Albino: 0-0> 70.4 4.250 (l-tailed)
15-15 63.2

6. Hood: 0-0> 27.8 4.025 (l-tailed)
15-15 12.6

Combined prob. 0-0>15-15 .(.04 (l-tailed)

Albino: 0-0>'fi 70.4 -<.30 (l-tailed)
15-0 62.0

G. Hood: 0-0)> 27.8 .<.10 (1—tailed)
15-0 19.8

Combined prob. 0-0>15-0 <{.08 (l-tailed)

Albino: 15-15 = 63.2 >.90 (2-tailed_)_
15-0 62.0

G. Hood: 15-15 = 12.6 41.20 (2-tailed)
15-0 19.8

AIbino: 15-0> 62.0 (.25 (l-tailed)
15-0-0 48.4

G. Hood: 15-0) 19.8 < .30 (l-tailed)
15-0—0 17.4

Combined prob. 15-0715—0-0 <.15 (1-tailed)

Albino: 0-0> 70.4 4.10 (l-tailed)
15-0-0 48.4

G. Hood: 0-0) 27.8 4.05 (1-tailed)
15-0-0 17.4

Combined prob. 0-0>15—0-0 <.01 (l-tailed)

 

With regard to the albinos there were no significant dif-

ferences in any of the comparisons made. Considering the

36

grey hooded rats, the 0-0 group exhibited a significantly
greater number of trials to extinction than both the 15—15
group, and the 15-0-0 group. After combining independent
significance levels, the significant findings were in the
comparisons of the 0-0 group having more trials to extincc
tion than both the 15-15 group, and the 15-0-0 group.

The following is a summary of the results obtained
with regard to mean number of trials to extinction:

l. A large significant difference was found between
the albino and grey hooded animals. The albinos had a
significantly greater number of trials to extinction than
the grey hoods.

2. The 0-0 group was found to have a significantly
greater number of trials to extinction than the 15-15 group.

3. The 0-0 group was found to have a significantly
greater number of trials to extinction than the 15-0-0
group.

4. No significant difference was found between the
mean number of trials to extinction of the 15-0 and 15—0-0
groups.

5. No significant difference was found between the
mean number of trials to extinction of the 0-0 and 15-0
groups.

6. No significant difference was found between the
mean number of trials to extinction of the 15-15 and 15-0

groups.

37

Mean Number of Trials to Reach the Median Latency
of Trials 1-30 of Extinction (7.5 sec.)

 

 

Because of the huge strain differences found in the
number of trials to extinction an additional measure was
computed in an attempt to reduce the strain differences.
The grand median latency of the first 30 trials of extinc-
tion of all 40 §§ was found to be 7.5 sec. The number of
trials it took each S to reach this median was found and
the mean for the two strains within the four groups ap—
pears in Table 8.

Table 8.--Mean number of trials to reach latency of 7.5

sec. during trials 1-30 of extinction for the two strains
and four groups.

 

 

 

 

0—0 15-15 15-0 15-0-0
Albino 11.4 7.8 10.0 8.8
Grey Hooded 9.0 9.0 7.6 10.0
Mean of Strains 10.2 8.4 8.8 9.4

 

A 4 x 2 analysis of variance of the number of trials
to reach the latency of 7.5 sec. for the four groups and
two strains yielded no significant main effects or inter—
action (Table XI--Appendix). Therefore, according to
this measure there were no significant differences among

the groups in resistance to extinction.

CHAPTER IV

DISCUSSION AND CONCLUSION

Mean Reciprocal Latencies

 

The results tend to indicate the following conclusions
with regard to the latency measure:

1. No statistically significant difference was found
in the mean reciprocal latencies of Trials 51-60 of acqui-
sition among the four groups. This finding tends to sug-
gest that the animals may have reached an asymptote of
responding at the end of acquisition which could have re-
sulted in the suppression of the possible measurable af-
fects of the effort variable upon the latency response.

2. There was no significant difference found among
the four groups in the decrements in mean reciprocal 1a-
tencies from the last 10 trials of acquisition to the
first 10 trials of extinction. The 15-15 group exhibited
a slightly greater decrement than the 0-0 group. Although
the difference is in the direction predicted by Hullian
theory, the difference was non-significant as predicted
by the generalization decrement hypothesis. The 15-0
group exhibited a slightly greater decrement than both
the 0-0 and 15-15 groups. This difference is in the

direction predicted by the generalization decrement

38

39

hypothesis. However, this difference was rather small
and not statistically significant.

The Hullian position would have predicted that the
15-15 group exhibit the greatest decrement. The generali-
zation decrement hypothesis would have predicted that the
15-0 group exhibit the greatest decrement. The data did
not seem to support either hypothesis. The 15-0-0 group
was observed to have the greatest decrement while the
other three groups (i.e., 0-0, 15-15, and 15-0) exhibited
decrements which were approximately equal in magnitude.

3. The 15-0-0 group had a significantly greater
increment in mean reciprocal latency from Trials 41-50 to
Trials 51-60 of acquisition than the 15-15 plus 15-0
group. It appears that reduction of the effort require-
ment during the final 10 trials of acquisition resulted
in facilitation.

The major questions which the results pose seem to
be: Why did the 15-0-0 group exhibit facilitation during
the final 10 trials of acquisition while the 15-0 group
did not seemingly exhibit facilitation during the first
10 trials of extinction? In other words, why did a change
in stimulus conditions produce facilitation in the case
of the 15-0-0 group and not in the case of the 15-0 group?
The change in stimulus conditions for the 15-0 group was
also accompanied by omission of reinforcement, while the

15-0-0 group continued to receive reinforcement with the

40

change in stimulus conditions. The correlation of reward
or nonreward with the stimulus change may have interacted
in such a way as to produce the results obtained. If

the decrements of the 15-0 and 15-0-0 groups are compared,
it might be argued that the 15-0 group does exhibit facili-
tation as compared to the 15-0-0 group. It is possible
that the time taken to leave the start box may not have
been a particularly sensitive index of the influence of

the effort variable upon behavior.

Mean Reciprocal Running Times

The results seem to indicate the following con-
clusions with regard to mean reciprocal running times:

1. The findings obtained during the final 10 trials
of acquisition are in agreement with Jensen's results of
no suggestion of a main effect with regard to the effort
variable. If effortfulness of the response had caused a
depression in the performance of the high effort groups
this would have yielded a greater increment for the
15-0-0 group, when effortfulness was reduced, as compared
to the 15-15 plus 15-0 group. The 15-0-0 group was ob-
served to have less of an increment in mean reciprocal
running time from Trials 41-50 to Trials 51-60 of acquisi-
tion than the 15-15 plus 15-0 group. However, this dif-
ference between the increments of the two groups was not

statistically significant. Therefore, it is concluded

41

that the 15-0-0 group did not exhibit the hypothesized
facilitation during the final 10 trials of acquisition
when the effort requirement was reduced.

2. The 0-0 group exhibited a significantly smaller
decrement from Trials 51-60 of acquisition to Trials 1—10
of extinction than the 15-15 group. This finding tends
to support the prediction of Hullian theory that high
effort causes a greater decrement in response strength
from acquisition to extinction than low effort does. It
could conceivably be argued that this effect may have
been caused by differences in habit strength, since the
0-0 group received 60 reinforcements while the 15-15
group received only 50 reinforcements, with regard to
the reSponse which was extinguished. According to Hul-
lian theory, habit strength increases as a function of
the number of reinforcements. Therefore, the 0-0 group,
which received 60 reinforcements for the response of
running the horizontal runway and then no longer received
reinforcement for this response, might have been expected
to exhibit less of a decrement than the’l5-15 group,
which received 50 reinforcements for the response of
running the inclined runway and then no longer received
reinforcement for this response. However, the 15-0
group received only 10 reinforcements for the response
of running the horizontal runway. It was this response

which was not reinforced during the extinction procedure.

42

Thus the habit strength of the response which was subjected
to the extinction procedure should presumably have been
weaker in the 15-0 group than in any of the other groups.
This group would have been expected to show the greatest
decrement in mean reciprocal running time. This was not
indicated by the data. Therefore, the greater decrement
of the high effort group as compared to the low effort
group does not seem to be related to differences in habit
strength.

3. The 15-0 group exhibited facilitation during
extinction as compared to the 15-15 group, but not as
compared to the 0-0 group. In fact, the 15-0 group was
observed to have a greater decrement than the 0-0 group
although this difference was not statistically signifi-
cant.

The major questions which the results pose seem to
be: Why did the 15-0 group presumably exhibit facilita-
tion during extinction as compared to the 15-15 group,
but not as compared to the 0-0 group? Also, why did the
15—0-0 group exhibit less of an increment during the final
10 trials of acquisition than the 15-15 plus 15—0 group?

At the start of the extinction procedure the 15-0
group was simultaneously subjected to a change in stimulus
conditions and to withdrawal of reinforcement. It has
been observed that nonreward of a previously rewarded

response often results in an "increase in response vigor"

43

(Amsel & Hancock, 1957, p- 126). This observable increase
has been termed "frustration effect." In other words,
frustration is viewed as functioning as an energizer of
behavior at the start of extinction. It is conceivable
that behavioral contrast may be dependent upon the state
of frustration of the organism. This might explain why,
in the present study, the 15-0—0 group did not exhibit
facilitation during the final 10 trials of acquisition

as compared to the 15—15 plus 15-0 group. Presumably,

no frustration was present during these last 10 trials
since reinforcement was given after each response. There-
fore, although the stimulus situation was altered, the
frustration component was not present. When both the
stimulus situation was changed and frustration generated,
as in the case of the 15-0 group during the first 10
trials of extinction, facilitation was exhibited by the
15-0 group as compared to the 15—15 group. Further,
facilitation due to behavioral contrast may be a function
of the inter-trial interval. It will be recalled that
behavioral contrast was observed by Stachnik in a Skinner-
ian situation in which the ITI was minimal. Perhaps the
effects of frustration and change in stimulus conditions
dissipate as a function of time. This might possibly
explain why, in the present study, the 15—0 group did not
exhibit any measurable facilitation as compared to the

0-0 group.

44

If any measure, of those used in the present study,
was to indicate the influence of the effort variable the
running time measure would be expected to be most likely
to do so. As mentioned by Jensen, an increase in the
vigor of the response also increases the effortfulness
of the response, and the response presumably involved
is that of running. This may partially explain why the
effect of effort was reflected at all in this measure
and not in the latency measure. Actually, there may have
been no difference in the amount of effort required to
leave the start-box, while that required to traverse the
runway did vary according to the groups. It may be con-
cluded that the running time measure reflected changes

in performance more than did the latency measure.

Mean Number of Trials to Extinction

 

Perhaps the most striking finding with regard to
the mean number of trials to extinction is that of the
huge difference between strains. The albinos exhibited
greater resistance to extinction than the grey hoods.

Of the 20 albinos run, nine were run for the maximum of
80 trials, whereas all the grey hoods extinguished with-
in 40 trials. Strain differences have also been found

in amount of exploratory behavior (Carr & Williams,

1957; Williams, Zerof, & Carr, 1962), degree of emotion-
ality (Broadhurst, 1958; Sines, 1962), amount of hoarding

(Stamm, 1954), and even in rate of bar-pressing (Pieper,

45

Garwood, Lewis, & Marx, 1962). In the latter study, in
which albino and hooded rats were used, it was found that
"the albino strain demonstrated the higher over all BP
(bar-press) rate irrespective of reinforcement concen-
tration" (Pieper, et al., 1962, p. 425). Rate of bar-
pressing is defined in terms of the number of responses
made during a period of time. In most of the studies
in which the effect of effort upon bar pressing was in-
vestigated, resistance to extinction was measured in
terms of number of responses made until some criterion
was reached. The present study also employed a measure
of resistance to extinction defined in terms of number
of responses (trials) made until a specified criterion
was reached. Therefore, if number of bar presses is
viewed as analogous to number of responses made in
traversing a runway, the findings of the present study
agree with those of Pieper, e§_al. The overall number
of responses made to a criterion of extinction was higher
for albinos than for grey hoods. In addition, if bar
press rate is viewed as a measure of speed of responding,
the findings of the present study with regard to albinos
running faster than grey hoods are also in accordance
with Pieper, et a1. findings.

When the strains were analyzed separately and the
independent significance levels of the various comparisons

combined the following conclusions were made:

46

1. As predicted by Hullian theory, the 0-0 group
(low-effort) exhibited greater resistance to extinction
than the 15-15 group (high effort). This effect was more
marked for the grey hooded animals than for the albinos.

2. No facilitation was exhibited by the 15—0 group
as compared to the 15-15 and 0-0 groups. However, the
resistance to extinction of the 0-0 group approached being
significantly greater than that of the 15-0 group, a re-
sult which is in accordance with the prediction of the
generalization decrement hypothesis.

3. No difference in resistance to extinction was
found between the 15-15 and the 15-0 groups. This result
is not in aggrement with that of Lawson and Brownstein
who found that the group trained and extinguished under
high effort exhibited greater resistance to extinction
than the group trained under high effort and extinguished
under low effort. It is possible that in the present
study the difference in the training and extinction situ-
ations was not as highly discriminable to the animals as
it may have been in the Lawson and Brownstein study.

Mean Number of Trials to Reach the Median Latency
of Trials 1-30 of Extinction

The data for the number of trials to extinction were
collected using two consecutive trials in which latency plus
running time was at least 120 sec. as the criterion of ex-

tinction. This had been the criterion used by Lawson and

47

Brownstein. However, it was found that this measure
resulted in tremendous strain differences, which were not
controlled for in the original design (i.e., by randomizing
order of running strains within each group). This led to
the consideration that an alternative measure of resistance
to extinction might make the data more easily interpretable.
Therefore, the present measure of the mean number of

trials to the median latency of Trials 1—30 of extinction
was employed as an indicator of resistance to extinction.
Using this measure strain differences were eliminated.

This measure also gave no indication of any significant
difference among the groups in resistance to extinction.

On the basis of this measure it is concluded that either
the effort variable had no influence upon resistance to
extinction, or that this measure was not sensitive enough

to indicate any difference that may have existed.

Conclusions

 

The following is a summary of the results obtained:

1. Significant differences between the two strains
were found with regard to running time and mean number of
trials to extinction. The albinos ran faster and had a
greater number of trials to extinction than the grey hoods.

2. No significant difference in the decrement
from the last 10 trials of acquisition to the first 10

trials of extinction with regard to latency was found between

48

the 0-0 group and 15-15 group. However, the 15-15 group
ran significantly slower during the first 10 trials of
extinction than did the 0-0 group. The 0-0 group also
had significantly greater resistance to extinction than
the 15-15 group as evidenced by the mean number of trials
to the extinction criterion, but not by the number of
trials to the median latency of Trials 1-30 during
extinction.

3. The 15-0 group exhibited facilitation in
running time during extinction as compared to the 15-15
group. However, the reverse relationship was observed
with regard to the latency measure, although the difference
between the two groups was not statistically significant.
No significant difference between the 15-0 and 15-15
groups was found in the two measure of resistance to
extinction.

4. The 15-0 group was observed to have a greater
decrement in latency and running time than the 0-0 group,
although not significantly greater. The 0—0 group also
exhibited a greater mean number of trials to extinction
than the 15-0 group. This difference approached being
statistically significant.

5. Facilitation in latency was shown by the 15-0—0
group during the final 10 trials of acquisition when the
effort requirement was reduced. Although facilitation
was observed in the running time measure, the increment

was not statistically significant.

49

6. The 15-0-0 group exhibited a significantly
greater increment in latency, when the effort require-
ment was reduced during acquisition, than that of the
15—15 plus 15-0 group. However, the reverse relation-
ship was observed with regard to the running time mea-
sure, although this difference was not statistically
significant.

7. The 0-0 group exhibited greater resistance
to extinction than the 15-0-0 group as measured by the

mean number of trials to extinction.

8. The possible interaction of frustration and

change in the stimulus situation in producing behavioral

contrast with regard to the running response is hypo—

thesized.

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REFERENCES

Aiken, E. G. The effort variable in the acquisition,
extinction, and spontaneous recovery of an
instrumental response. J. exp, Psycholt, 1957,

5;. 47-51.

 

Amsel, A. and Hancock, W. Motivational prOperties of
frustration: III. Relation of frustration effect
to antedating goal factors, J. exp. Psychol.,
1957, 53, 126-131.

 

Applezweig, M. H. Response potential as a function of
effort. J. comp. physiol. Psychol., 1958, 21,
55-59.

 

Broadhurst, P. L. Determinants of emotionality in the
rat: III. Strain differences. J. comp. physiol.

Psychol., 1958, 5;, 55—59.

 

Capehart, J., Viney, W. and Hulicka, I. M. The effect
of effort upon extinction. J. comp.4physiol.
Psychol., 1958, S1, 505-507.

 

Carr, R. M. and Williams, C. D. Exploratory behavior of
three strains of rats. J. comp. physiol. Psychol.,
1957, 59, 621-623.

 

Edwards, A. L. Experimental design in psychological
research. New York: Holt, Rinehart, & Winston,
1962.

 

Hull, C. L. Principles of behavior. New York: Appleton-
Century-Crofts, 1943.

 

Jensen, G. C. Learning and performance as functions of
ration sizes, hours of privation, and effort re—
quirement. J. exp. Psychol., 1960, S9, 261-268.

 

Lawson, R. and Brownstein, A. J. The effect of effort
and training-test similarity on resistance to ex-
tinction. Amer. J. Psychol., 1957, 19, 123-125.

 

Maatsch, J. L., Adelman, M. and Denny, M. R. Effort and
resistance to extinction of a bar-pressing response.
J. comp. physiol. Psychol., 1954, 41, 47-50.

 

Mowrer, O. H. and Jones, H. M. Extinction and behavior
variability as functions of effortfulness of task.
J. exp. Psychol., 1943, 33, 369-386.

50

 

51

Pieper, W. A., Garwood, C., Lewis, D. and Marx, M. H.
Differential acquisition of an instrumental response
in albino and hooded rats. Psychol. Rep., 1962,
11. 425—426.

Reynolds, G. S. Behavioral contrast. J. exp. anal.
Behav., 1961, 4, 57-71.

Sines, J. 0. Strain differences in activity, emotionality,
body weight and susceptibility to stress induced
stomach lesions. J. genet. Psychol., 1962, 19;,
209-217.

Stachnik, T. J. A habit strength analysis of the relation-
ship between response effort and resistance to ex-
tinction. Unpublished Ph.D. Thesis, Department of
Psychology, Michigan State University, 1963.

Stamm, J. S. Genetics of boardings: I. Hoarding differ-
ences between homozygous strains of rats. J. comp.
physiol. Psychol., 1954, 41, 157-161.

Stanley, W. C. and Aamodt, M. S. Force of responding
during extinction as a function of force require-
ment during conditioning. J. comp. physiol. Psychol.,
1954, 31, 462-464.

Weiss, R. F. Response speed, amplitude, and resistance
to extinction as joint functions of work and length
of behavior chain. J. exp. Psychol., 1961, S1,
245—256.

Williams, D., Zerof, S. A. and Carr, R. M. Exploratory
behavior of the crosses of three strains of rats.
J. comp. physiol. Psychol., 1962, SS, 121-122.

APPENDICES

52

53

Table I.--Mean reciprocal latencies of the four groups

during acquisition and extinction

 

 

 

Trials - 0 15-15 15-0 15-0-0
Acquisition

1-10 .387 .399 .400 .428
11-20 .764 .481 .545 .510
21-30 .017 .883 .704 .771
31-40 .555 1.124 .188 1.236
41-50 .626 1.375 .376 1.566
51-60 .750 1.596 .471 1.806
Extinction

1-10 .262 1.100 .973 1.107
11-20 .311 .212 .178 .226
21-40 .192 .098 .098 .111

 

Table II.--Analysis of variance of mean reciprocal laten-
cies of trials l-lO of acquisition for the four groups

and

two strains

 

 

 

 

Source SS df MS
Strains (S) .021 1 .021
Groups (G) .009 3 .003
S x G .062 3 .021
Error 1.745 32 .058
Total 1.837 39

 

Table III.--Analysis of variance of mean reciprocal
latencies of trials 51-60 of acquisition for the four

 

 

 

 

groups

Source SS df MS F p
Between .693 3 .231 1.116 4.250
Within 7.450 36 .207

Total 8.143 39

 

Table IV.--Analysis of variance of decrements in mean re-
ciprocal latencies from trials 51-60 of acquisition to

trials 1-10 of extinction for the four groups

 

 

 

 

Source SS df MS
Between .315 3 .103
Within 4.617 36 .128
Total 4.932 39

 

Table V.--Mean reciprocal running times of the two strains
(Albino-A and grey hooded-CH) within the four groups during
acquisition and extinction

 

 

 

 

0-0 15-15 15-0 15-0-0

A GH A GH A GH A GH
Acq.
1-10 .684 .440 .599 .369 .614 .433 .487 .522
11-20 .894 .545 .614 .378 .527 .430 .581 .527
21-30 .961 .614 .837 .539 .704 .528 .746 .734
31-40 1.183 .696 1.007 .598 .896 .692 .845 .810
41-50 1.113 .722 1.095 .677 .832 .710 .955 .874
51-60 1.137 .770 1.197 .765 .965 .678 .010 .906
Ext.
1-10 .960 .648 .726 .418 .715 .528 .740 .615
11-20 .426 .311 .416 .135 .306 .229 .397 .211
21-40 .394 .109 .382 * .291 .051 .312 .015

 

*All Ss reached criterion

55

Table VI.--Ana1ysis of variance of mean reciprocal running
times of trials 1-10 of acquisition for the four groups and
two strains

A

 

 

 

Source SS df MS F ,p
Strains (S) .240 1 .240 14.118 4.005
Groups (G) .033 3 .011

.S x G .126 3 .042 2.470 41.100
Error .557 32 .017

Total .956 39

 

Table VII.--Analysis of variance of mean reciprocal running
times of trials 51-60 of acquisition for the four groups
and two strains

 

 

 

Source SS df MS F p
Strains (S) .884 1 .884 19.217 < .005
Groups (G) .157 3 .052 1.130 NS
S x G .151 3 .050 1.087 NS
Error 1.465 32 .046

 

Total 2.657 39

 

Table VIII.--Analysis of variance of decrements in mean
reciprocal running times from trials 51-60 of acquisition
to trials 1-10 of extinction for the four groups and two

 

 

 

strains
Source SS df MS F ,p
Strains (S) .042 l .042 1.50 NS
Groups (G) .386 3 .129 4.61 41.01
S x G .029 3 .010
Error .904 32 .028

 

Total 1.361 39

 

56

Table IX.-—Summary of t-tests made on increments in mean
reciprocal running times from trials 41—50 to trials 51-60
of acquisition

 

 

 

 

Comparison Mean p

15-0-0 (Trials 51-60) .958 <.20 (2-tailed)
(Trials 41-50) .914

15-0-0 = .044 <.60 (2-tailed)

15-15 % 15-0 .070

 

Table X.--Analysis of variance of the number of trials to
extinction for the four groups and two strains

 

 

 

 

Source SS df MS F p
Strains (S) 17305 1 17305 71.21 <.005
Groups (G) 1382 3 461 1.90 <.250
S x G 488 3 163

Error 7779 32 2’43

Total 26954 39

 

Table XI.--Ana1ysis of variance of number of trials to
reach latency of 7.5 sec. during trials 1-30 of extinc-
tion for the four groups and two strains

 

 

 

Source SS df MS
Strains (S) 3 l 3.0
Groups (G) 7 3 2-3
S x G 40 3 13.3
Error 518 32 162.0

 

Total 568 39

 

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