THE EFFECTS OF PERSONALITY TRAITS on
EXPERIMENTAL GAMES ‘

Thesis for the Degree of M. A ,
MICHIGAN STATE UIIWERsm )
MARSHA H. KATZ ' '

1971 '

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THE EFFECTS OF PERSONALITY TRAITS
0N EXPERIMENTAL GAMES

By .
Marsha H}Skatz

A THESIS

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

MASTER OF ARTS
Department of Psychology

197]

ABSTRACT

This study reports on the effects that personality plays in the
choice of move in ekperimentaigames. Two trivial games were develOped,
one to test the trait of trust and the other to test competition. The
third game used was the chicken game. It was expected that the two per-
sonality traits would interact in the chicken game such that only those
who are high on trust and low on competition will cooperate. All others
were predicted to defect.

The two trivial games did not predict the choice of move on the
games nor did the interaction between the two personality traits pre-
dict the choice of move on the chicken game. A

it was found that the competition predicted the choice of move on
the chicken game. The competition game itself was.aiso a predictor of
the choice of move on the chicken game.

Sex differences were found to be significant in the pattern of

moves following a defection by the opponent.

ACKNOWLEDGMENTS

The author wishes to thank Dr. James L. Phillips and Dr. Lawrence
A. Hesse for their help and guidance in this study. The author wishes
to express her gratitude to Dr. Jeanne Gullahorn for her criticisms.

Finally, much appreciation Is given to her husband for his criti-

cisms and patience during this period.

iI

. TABLE OF CONTENTS

Page

List of Tables ............. . ......... ' ...................... . ....... iv
List of Figures. .......... ... .................... ... ............ ....v
lntroduction.. ................. ... .................................. l
Laboratory Studies of Conflict ................... . ......... ....3
Personal 'ty. 0 O O O O O O O O O O O O O O O O O O O O O O O O O I O O O O O O O O O O O O O O 0 O O O O O O O O .6

Sex Differences ..... . .......................................... 8
Situation ....... . .............................................. 9
MethOd OOOOOOOOOOOOOOOOOOOOOOO O OOOOOOOOOOOOOOOOOOOOOOOOO O ..... ......lh
Results ............ . ............................................... i8
Paper and Pencil Personality Tests.. ....... ........ ........... l8
Analys‘SOOOOOOOO .............. ... ..... O 0000000000 ......OOOOOOOIB
HymtheSis l, "’ "IOOOO. 000000000 .....OOOOOOOOOOOOOO0.0.0.0019

Sex Differences ..................................... .. ....... l9
Matrix I and Matrix ii as Predictors of Matrix III ......... ...2l
iterated Chicken Game... ....... ........................... ..2i
HypotheSIS 'V ...... O ...... O O ........... O O O O O O O O O O O O O O O O O O O O O O .02]
Level of Defectlon over Time ...... ...... ..... .................25
Discussion ......................................................... 30
Summary... ................ . ............. . ........... .... ......... ..3h
References .......................... . ............... . ...... ........35
Appendix A. ................................. . ........... . .......... 37
Appendixa ..... e. ooooooooooo ooooooeoeooeo ..... o ooooo 0000.0. 000000000 90“]

LIST OF TABLES

Table Page
i. Summary of Analysis of Variance:. The Effects of Person-

ality Traits in Different Matrices... ..... ............... ..... 20
2. Correlations: Personality Traits for-Males and Females

as It Effects the Different Matrices ...... . ..... '.... .......... 22
3. Percentage of Defections on Different Matrices, by

Personality Traits ............. . ...... . ...... ... .............. 23
4. Percentage of Defection on Matrix Iii by Moves on

Matrices l and II in Total Sample ............ ..... ............ 2h
5. Summary of t Test. Competition Game as a Predictor of Move

on Chicken Game ................................. ..... ......... 25
6. Summary of t Tests, Males and Females over Period of

Trials ........................................ .. .............. 29

iv

LIST OF FIGURES

Figure , Page
i. Normal Form of 2 x 2 Game ....................................... 3
2. Chicken Game. Matrix III ....... . ............ . ..... .. ........... h
3. Competitive Game. Matrix ll ................................... l0
h. Trust Game. Matrix i .......................................... l0
5. insturction Game ..................... . ..... . ..... . ............. i5

Number of Defections over Time. Females. .................... ..27
7. Number of Defections over Time. Males ......................... 28

Introduction

An aspect of psychological research of great potential relevance
to world affairs is the study of the influence of personality variables
on reactions to mixed-motive situations. It is interesting to speculate
how history might have been different if a certain leader had not been
prominent at a particular time. Notable examples are the Nazi regime
in Germany and the “Camelot” era during the administration of John
Kennedy.

if it is true that the leader of a country may influence that
country by his personality, it follows that leaders of smaller areas of
concern may also have influence in that area. An ambassador in a for-
eign country uses his influence in that sphere to maintain certain dip-
lomatic relations. He also imparts information to his superiors. This
information may be influenced by his cognition of certain events; and
this cognition may be influenced by his personality.

The description below is one example of how a person in a situa-
tion of influence had a perception of events that made a considerable
impact on American foreign politics. Holsti (l96l) presents evidence
for the Dulles role in shaping American policy regarding the Soviet
bloc. He claims that Dulles viewed the Soviet Union Government as
”bad“: a trinity of atheism, totalitarianism, and communism. Dulles,

in order to maintain his previous ideas, either misinterpreted or

disregarded data that probably would have led other people to change
their opinion of the Soviet Union.

Weber (1961) states that the more ambiguous the cognitive and
evaluative aspects of a decision making situation, with the responsi-
bility being mostly on one person, the more likely that personality
variables are likely to assert themselves. In support of this view,
Marquis, Guetzkow, and Heyns (l9Sl) in a study of business, government
and industrial conference groups, found that an individual in many
cases was motivated by his personal needs rather than by the situation
at hand. in a survey of these officials, they found that those in
lower positions did not feel that personality played a great part in
behavior, but those at the higher echelons said it did. This was es-
pecially true at times when information was incomplete and stress
great.

This kind of analysis suggests that studies need to be done re-
garding the effect of personality on cognition and thus on the behavior
of an individual. This is particularly important with reference to
persons of much power or influence.

it is too complex a problem to study world leaders and how their
personality traits effect their decisions on world affairs. This is
not only because of their status and therefore their inaccessibility,
but also the nature of the problem. To isolate one personality trait
and determine a controlled way of testing what effect it has on deci-
sion making is difficult to do in the "real world." The possibility
of running laboratory experiments with world leaders is generally re-
garded as infeasible and incomprehensible. But laboratory studies can

be done that show that there is a relationship between personality and

behavior, or decision making. Once this relationship is established,
then the analysis can be extended to the field.
Laboratory Studies of Conflict

The experimental game is a useful way to study decision making in
conflict situations. The game offers a situation that involves choos-
ing between a ”cooperative” or ”competitive" act. in the 2 x 2 game,
there are two people each having two choices concerning the amount of
payoff possible for himself and another person. Each person makes his
move separately, but the joint move actually determines the payoff for
each subject. Thus, the game is designed such that each player's pay-
off is not only dependent on his own choice, but also upon the choice
the other person makes. See Figure l for the characteristic, normal

form of the 2 x 2 game.

Person I

Choice A Choice 8

 

Choice A I Ii

 

Person 2
Choice 8 iii iv

 

 

 

 

Figure I. Normal Form of 2 x 2 Game.

The theory of games assumes the following:
l) A person has full information, l.e., knows the alternative
available both to himself and his Opponent and has a knowledge of the
preference patterns of the other player in the situation.

2) Each person has a preference ordering over the outcomes

available .

3) People act to maximize their utility, i.e., the theory
assumes rational players (Luce and Raiffa, l967).

Rapoport and Guyer (l966) indicate that there are 78, 2 x 2 games,
when the payoffs are considered only on an ordinal scale. Some of those
can be classified as ”trivial” games. Those games have a solvable
strategy for both players, i.e., if they both “perceive" the game simi-
larly to game theory, both should behave cooperatively; both should
make the choiCe with the highest joint payoff. They state that these
”trivial” games are of no theoretical interest. And thus, they have
not been dealt with in the literature. Research has basically centered
on the prisoner's dilemma game and the chicken game. The preference
for player I in the chicken game should be: If > i > ill > IV. Figure

2 shows the matrix for the chicken game.

 

 

Player l
A A
l 2
B
i 2
3 A
Player iI \
B h
2 l
2' 1

 

 

 

Figure 2. Chicken Game. Matrix iii.

When trying for the outcome in cell ii, the most preferred outcome, one
takes the risk of receiving the outcome of cell IV, the least preferred
outcome. instead if player i chooses to try for cell I (his second

choice), the worst that can happen is that he receives his third choice

(cell iii). Trying for the second choice in order not to be caught with

the last choice, is called the minimax strategy. This analysis holds
true for both players.

The chicken game can be analyzed on the basis of a combination of
two psychological traits: trust and competitiveness. Iif a person is
trusting of others and not competitive, it is likely that he will
choose choice A , believing that the other person will choose B . if
this trusting person is competitive, then he would pick choice A , which
would enable him to earn more. He would be taking advantage of ihe
cooperativeness of the other person. This is, of course, contingent
upon his ”trust" of the other person to choose choice B .

if the person is non-trusting, he believes that thl other person
will try to get the most for himself. Thus he has two choices: take
the best he can, i.e., two points and let the other person get the
greater amount; or he can get even and make the other_person suffer
also, with both receiving the least amount.

It can be seen that the chicken game is fairly complex on a psycho-
logical level. Therefore, it is prOposed that various simple games,
games that are mathematically solvable, should be developed that would
be dependent upon particular psychological traits. These simple games
might be more useful in studying these traits in isolation. Certain
games with dominant strategies can be deveIOped that would differenti-
ate between people on sdéh traits as trust and competitiveness. This
kind of game may prove to be as interesting psychologically as the
chicken game. This could be justified by the issue that psychological
interest is generated when new or unusual motives can be used to explain

behavior. Thus, the failure to choose the "rational move“ in a game, if

it can be explained by a ”new motive," is of interest to the psychologist.

It may be that "trivial" games can show this failureand isolate the
motive most readily.

This study concerns itself with variables that might affect the
choice of movean individual makes. What influences some people to
choose the competitive instead of the cooperative move in a chicken
game; or in the simpler games, what makes a person choose the non-
dominant move? These variables can be subsumed under two major head-
ings - Personality traits and Situational variables.

Personality

Laboratory studies of conflict have found contradictory results
concerning the relationship between personality traits and behavior.
One common explanation for this is that the situations are different
in the different experiments; thus some elicit the personality traits,
while others do not. Not only do some of the differences revolve
around the situation, but also around the various personality traits
chosen for study in any experiment. Different experiments have been
concerned with a variety of personality traits in various situations.
Terhune (l968) has summarized these personality and attitudinal vari-
ables studied in relation to conflict and cooperation.

A number of studies (Hrightsman, l966; Deutsch, i960; Lutzke,
1960; McCllntock, Harrison, Strong, and Gallo, l963; Marlowe, l963;
Terhune, l968) have found that personality traits are correlated with
cooperativeness and competitiveness in game situations.

Wrightsman (l966) attempted to assess thirteen variables assumed
to be related to game behavior. He administered a pre-test a month
before his g3 participated in the experiment. 39 were defined as

trusting if they chose the cooperative choice on a-2 x 2 prisoner's

dilemma game and expected the other player to choose cooperatively
also. These subjects had generally more positive attitudes about hu-
man nature: seeing people as more trustworthy, more altruistic, and
more independent than did distrusting Ss.

Deutsch (l960) found that the F scale could be used reliably to
predict game behavior. He found that the low F scorers were the most
cooperative and high F scorers most competitive in the prisoner's
dilemma game. i

In Marlowe's (l963) study, subjects played a prisoner's dilemma
game against a stooge who always played the cooperative choice. Fif-
teen of the 37 male S; were consistent and extreme non-cooperators,
while there were nine subjects who were c00perative. The non-
cooperators scored higher than the cooperators on need for aggression
and autonomy. Cooperative E? scored higher on need for abasement and
deference on the Heilbrun adaptation of the Gough Adjective Checklist.

Terhune (l968) selected Es high in either achievement affiliation
or power motive. He found that ”motive does predispose individuals to
play the Prisoner's Dilemma in different ways, but that these tend to
be wiped out the more threatening the situation." The threatening as-
pect of the experiment was varied by using three different matrices for
the one trial game. These matrices varied in their likelihood of pro-
ducing cooperation. ,

Lutzke (l960) used a different procedure than the above eXperImen-

l
ters. His subjects were rated as internationalists or isolationists

 

" A _
An internationalist was defined as one who trusts other nations
and is willing to cooperate with them. They would tend to perceive in-
ternational organizations such as the United Nations as deterrents of
war and consider international tension reducible by mediation.

by a pre-test before the experiment. They then were placed in pairs
based on similar traits. Each of these pairs played a prisoner's
dilemma game. Lutzke found that internationalists made significantly
more cooperative choices than did isolationists. Thus, the inter-
nationalist, defined as trusting, was also non-competitlve in the
game situation. This grOUp did not "exploit" the other person. Even
though they believed that the other subject would cooperate, they did
not take advantage and ”defect” for the possibility of earning more
money. A most interesting finding from this experiment was that his
control group (selected randomly from the population of college stu-
dents) did not differ significantly from the international group. Thus,
it seems that the internationalists are not more cooperative than the‘
general population of college students, but rather that the isolation-
ists are more competitive. McCllntock, Harrison, Strang and Gallo
(l963) also found that internationists tend to be more cooperative than
the isolationists. They found this to be the case no matter what
strategy the other player used.
Sex Differences

One of the most salient characteristics is the sex of the subject,
yet it is a variable that has not been studied extensively. Most ex-
perimental work is done using only males as subjects. The few findings
that have been determined in experimental work are not yet sufficient
to offer an acceptable explanation for the differences. Rapoport and
Chammah (l965) have found males to be more cooperative than females in
experimental game situations. Halpin and Pilisuk in a prisoner's
dilemma game, had subjects predict the move of the other §s and then

play the game. When they predicted the cooperative move, males tended

to defect and earn more points than the females. Komorita (l965) as in
the Halpin and Pilisuk study, found females to be more cooperative than
males. O'Grady (I970) has duplicated both sets of results by including
as a variable the type of strategy the §_used against the S}. O'Grady
found that females were more competitive against a contingent strategy
(tit-for-tat), which was the strategy used in the Rapoport and Chammah
study, while males were more competitive against a non-contingent strat-
egy as in the Halpin and Pilisuk study and in Komorita's study.

Vinacke's explanation that males are exploitative, while females
are accommodative, seems to offer a descriptive framework that partially
fits the above results. Against a non-contingent strategy, males do
tend to exploit the situation by playing competitively while females do
not. Hales also do not play competitively against a tit-for-tat strat-
egy where they could not exploit the opponent. The explanation does not
seem to hold up for females playing against a non-contingent strategy
without the added assumption that females find a contingent strategy
aversive and thus play competitively to get even with the opponent.

Grant and Sermat (i969) found males to be more submissive than
females in the chicken game, except against an opponent who was viewed
as being inferior. In that case, there was very little difference
between males and females in regard to exploitation. This result is
contrary to the Accommodative-Exploitative hypothesis.

Situation

As discussed above, one cannot isolate which combination of the .
psychological traits of trust or competition is influencing the choice
of move in the chicken game. But games can be set up to study one

trait at a time by using what Rapoport calls "no conflict_games."

IO

The game shown In Figure 3 is dependent upon the trait of competi-

tion.

Player l

 

Player ll

 

 

Figure 3. Competitive Game. Matrix ii.

It was constructed such that the competitive choice (A2) of player i
2

can be explained only by a desire to maximize the difference between
one's own and the other's payoff. The payoff matrix Is such that the
competitive choice enables the player to get a higher payoff than the
other player, only by sacrificing "i" point. This is similar to the
maximizing difference game developed by McCllntock and McNeil (l966).

Switching cells II and Iii, produces a game that is dependent upon

the trait of trust.

Player i
A‘ A

L
a

Figure A. Trust Game. Matrix I.

Player II

 

Both of these games are classified by Rapoport and Guyer as no-conflict
games with neither player having a dominating strategy. In the later
form, the choice of A by player i could be explained as follows:
player i might feel that player Ii was competitive and would try to
make player Itake a lesser amount than himself; thus, player Ii is
going to choose B . If player ii chooses B , than player I Is best off
by choosing A'. Tn this way, he would get iwo points instead of zero
points. Thiszform of behavior reflects an underlying distrust of other
people. i

Thus far, we have discussed two games and two different personality
traits: trust and competition. The choice of move in the chicken game
may be infernced by both of these traits. The two traits may interact
in determining a person's strategy. For instance, if a person is trust-
ing and competitive, he may choose the competitive move because he
realizes that he can eXpioit the other person.

The games presented above each entail different types of problems
for the participant. He is placed in a situation where he has two pos-
sible moves. The subject must make a decision regarding which move to
make. Various questions may go through the subject's mind before mak-
ing the final decision. The answer given and the final decision itself
will reflect to some extent the person's personality. Such questions
probably involve his view of man in general: is man greedy and out to
get all he can, or is he cooperative, dividing scarce commodities
equally between people? Is it worth the risk of getting a low reward
to try for a higher amount, or is it better to take the security? is

the chance of gain worth the associated risk? These questions that may

be raised in the experimental session are seen as similar to those that

I2

occur in everyday interpersonal situations.

This study involves two personality traits that seem related to
many of the questions that can be raised in experimental games: trust
and competition. Two games were chosen that seemed to elicit one of
these traits and one game was chosen which elicited both.

A model is devel0ped which will predict from personality character-
istics as measured by a paper and pencil test, and from the games which
elicit one trait each, what choice will be made in a chicken game.

It is hypothesized that:

i. There will be a monotonic relationship between the level
of trust and the choice of move on the trust matrix; distrust showing
the least cooperation and trust showing the most. The degree of trust
will be measured by Leary's interpersonal Checklist (l95h). (Appendix
A).

2. There will be a monotonic relationship between degrees of
competitiveness and the choice of move in a competitive matrix; high
competitors choosing the competitive choice, and low competitors being
cooperative. Competitive scores will be determined by Leary's Inter-
personal Checklist.

3. The interaction of the two traits will predict which choice
the subject will make in the chicken game; those high on trust and high
on competition will choose cell A ; those high on trust and low on com-
petition will choose A ; those log on trust and low on competition will
choose A ; and those llw on trust and high on competition will choose
A2. (Se: Figure 2 for matrix.)

A. The choice of move on the first two matrices will predict

the move on the chicken move. Those who cooperate on Matrix l and

l3

Matrix II (C-C) will cooperate on the chicken game. Those who defect

on one or both matrices will defect on Matrix iii.

Method

Subjects: Subjects in this study were l62 Michigan State University 9‘?
students selected from a pool of approximately 500 students who re- f
sponded to an advertisement in the student newspaper. The selection
was on the basis of pre-test scores on the Leary interpersonal Check- 1
list. A subject was selected for participation if he scored either L
below the 33rd percentile or above the 67th percentile on both the
trust and competitive sub-scales of the checklist of this sample.
Apparatus and Materials: The stimuli were 2 x 2 matrices presented on
a rear projection screen. There were four lights, one on each corner
of the screen that gave the §s the information of which cell had been
chosen.
A small box was used to indicate the §s response. A light on this
box was used as a signal to the S; as to when to make their response.
The response was indicated by pressing one of two buttons on the box.
There was also a pair of earphones for each.§ over which all instruc-
tions were given. The equipment was controlled by a PDP8/i computer.
Procedure: The session began after each-S was seated in his individual
cubicle. They were then given a short questionnaire which consisted of
six essay questions. §s were allowed to spend five minutes on each
question for a total of 30 minutes.

When everyone had completed this task, the form was collected and

lh

l5

all were instructed to put on their earphones. The subjects were told
that they were participating in a game in which they could earn a cer-
tain amount of money. The game was explained in detail while an in-

struction slide was presented on the screen. The instruction slide was
a 2 x 2 matrix that was similar to the subsequent experimental matrices.

The instruction matrix is shown in Figure 5.

 

 

Player I

A A
I 2
B 'I i

l
Player ii V

B I 3

2 I A

 

 

 

. Figure 5. Instruction Game.

Students were asked questions about the payoff structure to de-
termine whether they understood the matrix. When everyone answered two
questions in a row correctly, it was assumed the matrix was understood.

When it was established that each §_understood the game, the in-
struction matrix was changed to one of the ”trivial" matrices. For
half of the groups, the trust matrix (hereafter referred to as Matrix
I) was played first. (See Figure A.) For the remaining.groups, the
“competitive matrix” (Matrix II) was played first. (See Figure 3.)

Questions were asked about the matrix as before. After everyone
had again answered two questions correctly, the S; made their choice by
pressing the button under the column of their choice. One second after

the last person made his decision, the matrix was changed. The §_who

l6

was presented Matrix I first, was then presented with Matrix ii. Those
who saw Matrix ii first, saw Matrix l second. The same procedure of
testing for understanding the game was used for the second set as was
for the first.

Next, a third matrix (Matrix iii) was presented. This matrix fit
the criterion of the game Rapoport and Guyer (l966) call ”chicken“.
(See Figure 2.)

Questions were asked as before, until everyone answered two ques-
tions correctly. When this criteria of understanding was reached, the
Ss made their choice of move. Matrix III was presented for nine more
trials. After each trial, the §s were given the information as to
which call had been selected by both himself and his partner. The Ss
were informed that they were playing one of the other §s for each game,
and that each game would be played with a different partner. In actu-
ality, §s were playing against a preset program which c00perated on all
but one trial. The defection took place on the third or seventh trial
of the iterated chicken game.

The Es did not know how many trials there would be. No communica-
tion was allowed between §s and the doors of the room were partially
closed to block any visual contact. (See Appendix B for instructions.)
2221223 The variables of this experiment were: level of trust (high
or low), level of competitiveness (high or low), sex of subject, order
of presentation (Matrix l, Matrix ll, Matrix Iii or Matrix ll, Matrix l,
Matrix III), and defection on the third or seventh trial. Each of the
variables was dichotomous and thus the design was a 25 factorial.

For each group of four subjects, the independent variables of sex,

order of matrix, and trial on which the programmed defection took place

l7

remained constant, but whether their level of trust and competition was
high or low varied within the group.

The dependent variables were the choice (i or 2) of the subjects
for each matrix. There was one dependent variable each for Matrix l and
Matrix Ii and for the chicken game without information about payoff.

For the chicken game with feedback, there were nine trials. The depen-

dent variable being the average number of defections.

1;:- )‘__xd _‘_1u‘a-v‘-1i
'I

I

-_ !

..‘Erfiiix'ie a

Results

Paper and'Pencii PerSOnaiity‘TeSts

The two personality traits of trust and competitiveness were inde-
pendent of each other (r = .Dih for total sample; r - 0.00 for the ex-
treme 80 scores).
Analysis: An analysis of variance was performed for each of the inde-
pendent variables. Not all interactions were computable. There were
some empty cells in the total analysis as half the subjects were elimi-
nated from the analysis of the effects of personality traits on the
different matrices. These subjects were not used because there were
too many people with scores close to zero (or average) and the hypothe-
ses were concerned with those who were extreme in the traits observed.
The elimination of so many subjects after the study was run, made it
impossible to ensure that all cells were filled.

To obtain all information available, the data were analyzed a num-

ber of times, always holding the personality trait variables constant,

while changing the other variable submitted for analysis (sex or order).

An analysis of variance would not be computed for females since
there was not enough subjects to fill each cell. Since the analysis of
variance could not be computed, correlations for both males and females

are included.'

l8

QJ‘.‘ .11....54'...” a
I

'9

Hypothesis i, II, and iii: Hypothesis l states that those who had high
trust scores on the Leary Checklist would c00perate on the trust matrix
(Matrix l), while those who had low trust scores would defect on that
matrix. The test of this hypothesis indicated no effect (F - .00l,

df . 1,38).

Hypothesis ll predicted that those who scored high on the compet-
itive scale of the personality test would defect on the competitive
matrix (Matrix ii, while those who were low on competition would co-
operate. This effect was also non-significant (F - l.hO, df f i,38).

Hypothesis iii postulated that the interaction between the two
personality traits would predict the choice of move on the chicken game.
it was expected that those who were high on trust and low on competition
would cooperate while all others would defect. This proved to be insig-
nificant (F - .030, df - i,38). Table i presents the summary table for

the analysis of variance.

 

Unexpected Findings} The competitive sub-scale of the personality test
proved to be a significant predictor of the move chosen on the chicken
game (F = h.33,df - l,38, p < .05). in the highly competitive group,
#32 of the Es defected, while in the low competitive group only 202
defected.

Sex Differences: Hypothesis l: the trust trait correlation with

 

choice on Matrix l was higher for females but not for males (r . .28
for females; r - -.07 for males). This was not significant. The per-
centage of defections in the low trust group for females was #02, while
it was lSZ in the high trust group. For males, lOZ defected in the low
trust group and lSZ defected in the high trust group. -For the males,

competitive personality traits correiated more positively with the

- "AUV'K: l“ E-no—1
.

‘3...

'Frn—‘W.

 

Table i.

20

Summary of Analysis of Variance:

The Effects of Personality Traits in Different Matrices.

fi

 

 

 

 

Trust subscaie of Leary test df ms F
trust matrix (Matrix i) l .000l 0.00i
competitive matrix (Matrix ll) i .0223 .i966
chicken (Matrix iii) l l.hh2 l.hh

Competitive subscale
trust matrix (Matrix l) i .ll82 .782
competitive matrix (Matrix ii) i .160h l.h08
chicken, I .8h3 h.33l*

Sex
trust matrix (Matrix i) l .228 i.“82
competitive matrix (Matrix Ii) l .003 0.02h
chicken l .030 0.i550

Order
trust matrix (Matrix i) l .060 ..0027
competitive matrix (Matrix ii) i .007 .0633
chicken i l.20i 6.i7*

Trust X Competition
trust matrix (Matrix i) l .h347 2.875
competitive matrix (Matrix ii) i .0i57 0.i3
chicken l .0059 0.03

 

7': p<

.05.

2|

choice of move on the trust game (r - .23) than for females (r - .05),
but it was non-significant. Table 2 summarizes the correlations.

Hypothesis iii states that the interaction of trust and competition
should predict cooperation on the chicken game. The prediction was that
the high trust, low competition (HT, LC) group would have the highest
rate of cooperation, while the high trust, high competition group (HT,
HC), the low trust, low competition (LT, LC), and the low trust, high
competition (LT, HC) would have higher rates of defection.

Males in the HT, HC group defected more than the Es in all other
groups. Females did not show any interaction effects. The probability
of cooperation could be predicted by the level of competition. Table 3
contains thepercentage of defections for the four groups.

Matrix l and Matrix il as Predictors of Matrix iii: Hypothesis iV
states that those who cooperated on Matrix l and cooperated on Matrix
ii (C-C) were expected to cooperate on the chicken game. The other
three groups (cooperate on Matrix l, defect on Matrix ii (C-D); defect
on Matrix l, cooperate on Matrix il (D-C); and defection both (D-D))
were expected to defect on the third matrix. .

0n the first trial of chicken, the hypothesis was not supported.
All groups had high levels of cOOperation (C-C, 7l2 cooperation; C-0,
69%; D-C, 75%; and D-D, 70%). Table h contains the summary of percent-
ages of defection on the chicken game for the four groups based on pre-
vious moves.

iterated Chicken Game
Hypothesis iV: The results as derived from hypothesis IV were expected
to be the same on each trial of the iterated chicken game as the one

trial game of chicken. For the first trial, the hypothesis predicted

22

Table 2. Correlations: Personality Traits
for Males and Females as it Effects the
Different Matrices.

 

Male

Trust subscale r
Matrix i -0.076
Matrix ii 0.076
Matrix lli -0.l09

Competitive subscale

Matrix i .2268

Matrix ii - .2268
Matrix ill .2l82

Female

Trust subscale

Matrix I .280

Matrix ii .000

Matrix iii .053
Competitive subscale

Matrix i 0.056

Matrix ll 0.000

Matrix Ill 0.267

 

23

 

 

 

 

 

 

 

 

NN. ON. m_. mN. N. .. a. N. N. _. as he
NN. a. m_. in. m. N. a. m. _. .. q: es
m_. N. N. mo. N. N. _. N. N. o, as p:
mN. ms. mo. mN. :. m. N. m. o m. u: e:
.oao» .xu_;u .meou up .xo_;u .mEOQ a» .xu_co .asou up

—mu0._. mO—mfim mv—mz

.mu_ech >u__ec0mcom >3 .moo.cuez

acocomm_o co mcomuuomoa mo omeucoocoe

.m 2...:

2“

Table 4. Percentage of Defection on
Matrix ill by Moves on Matrices

 

 

 

 

 

i and ii in Total Sample.
Matrix iii First Second
First Chicken iterated iterated
Game Chicken Game Chicken Game
Males
cc 312 27% 33%
CD l72 502 50%
DC 33% 222 22%
DD #02 60% 602
Females
CC 27% 28% 282
CD #52 632 55%
DC l72 25% 33%
DD 202 402 no:
Total
CC 29% 28% 312
CD 3l2 57% 522
DC 25% 2&2 28%
DD 30% 502 502

 

25

the level of defection correctly on all but the D-C group; C-0 and 0-0
groups both had high levels of defection (572 and 50% respectively),
while the C-C had only 28% defection.’ The D-C group defected even less
than the C-C group (24%). The second trial of chicken remained in that
same pattern for the four groups, C-C and D-C being low in the level of
defection, while C-0 and D-D remained high.

Unexpected Findings; The move on Matrix ii (competitive game) tends to
be a significant predictor of behavior in the chicken game. Those who
choose the competitive move on Matrix ll, tended to defect on the
iterated chicken game for games one and two. This was regardless of

the move on Matrix i (first game). (See Table 5 for t tests.)

Males Females

 

Matrix iii

First chicken game t-l.0 t-l.0
First iterated

chicken game t=5.3** t-2.72*
Second iterated

chicken game t=7.3** t-l.8

 

 

* p < .05.
l**p < .0].
Table 5. Summary of t Tests.
Competition Game as a Predictor of Move on Chicken Game.
Level of Defection Over Time
There were an increasing number of defections on each trial of the.
chicken game, except on the trial after the programmed defection. When

a defection occurred on the third trial, there was a non-significant

 

26

decrease in the number of Es defecting. Females stayed at this lower
level for the rest of the trials, while the number of males who de-
fected started to increase after three trials had passed (t - 3.8,

df = 3.8, p < .05). When the programmed defection occurred on the
seventh trial, there was a large decrease in the number of Es defecting
on the next trial, significant at the .05 level for both males and fe-
males. 0n the following trial, females increased in their number of de-
fections to the level prior to defections (t = 3, df - hi, p < .05),
while males did not increase their level of defection (t - 0). (See

Figures 6 and 7, and Table 6.)

Number of Defections

30

25

20

l5

l0

27

Figure 6

Number of Defections over Time: Females

 

Trials

X-—-X
Computer defects
on trial 6

0--0
Computer defects
.on trial l0

4 2-5. .UAd—id" "\31I
.
i

 

l2

Number of Defections

30

25

20

l5

l0

 

28

Figure 7

Number of Defections over Time: Males

Trials

X--X .
Computer defects
on trial 6

0-—0
Computer defects
on trial 10

 

29

Table 6. Summary of t-Tests, Males
and Females over Period of Trials

 

Males

Computer defects on trial 6
trial 6, 7 t-D, df=39

trial 9, l0 t=3.3, df=39*

Computer defects on trial l0
trial l0, ll t-2.28, df-HB

trial ii, 12 t=0, df=h3

* p < .05

 

Females

Computer defects on trial 6
trial 6, 7 t-.02, df-3h

trial 7. 8 t-.36, df-Bh
trial l0, il ’ t-.56, df-3k
trial ll, l2 tiO, df-3h

Computer defects on trial l0

trial l0, ll ' t-3.0, df-hi*

trial ll, l2 t-3.lh, df-hl*

F- Ans.
‘ 1
6. ‘

 

Discussion

Only the 80 most extreme scores on both subsets of the Interper-
sonal Checklist were used in the final analysis since most of the scores
clustered around 0, even when using people who scored below the 33rd
percentile or above the 67th percentile on both the trust and competi-
tion subscales of the checklist.

Personality,Scores

 

The personality scores did not predict the choice of move for any
of the hypotheses, but the competitive subscale was a significant pre-
dictor of the move on the chicken game.

Since neither trust nor the interaction of trust and competition
was significant, it did not seem to matter whether or not subjects
trusted the other person to cooperate or not; they still risked possi-
bie greater loss to earn extra points. A possible explanation is that
everyone believed that their opponent would cooperate, regardless of
their scores on the trust subscale of the personality test. Unfortun-
ately, unlike Halpin and Pilisuk, we did not collect information re-
garding what move §§ thought the other person would choose.

The choice of move on the trust matrix was predicted for females
by their score on the trust personality test, but the choice of move
for males was predicted by the competitive subscale of the test. The

males who are competitive seem to project their own competitive urges

30

 

3i

on others. They see others as trying to ”exploit” them,so they play
the minimax move. Another possibility is that the competitive male is
actually more interested in not losing when there is no way of getting
more than his opponent. He may view the game as having a possibility
of losing or trying; so rather than earn more money by choosing the co-
operative move and take a chance on losing, he plays non-cOOperatively.
It seems that the competitive trait overrides the trust trait for males
in the competitive situation of game playing. This explanation, of
course, needs further research.

Response on the competitive matrix (Matrix ii) is not predictable
by either subscale. The reasons may be varied. Competition is a com-
plicated trait, and the personality scale may be measuring a different
type of competitiveness than what is involved in the game. The person-
'ality scale seems to be getting at a more self-interest type of compef
tition while the game is measuring ”competition against another" or a
desire to beat the other person. Another possibility is that the game
itself does not have a big enough payoff to elicit a competitive move
from a competitive person.

Matrix l and Matrix ii Predicting Matrix iii: it seems that competition
overrides the trait of trust. In the groups where gs defected on the
competition game, they tended to defect on the chicken game, as pre-
dicted. If the defection took place during the trust game, there was

no tendency to defect on the chicken game. Thus, though the chicken
game was supposed to be a "mixed motive” game, it seems that competi-
tion is an important motive which may be a sufficient predictor of the
move to be chosen on this game. Whether competition overrides trust

just in this mixed motive experimental game, or whether it will occur in

32

other games or "real life” situations requires more research.
Level of Defection over Time: As §s became more secure that the other
person was cooperating, there was a greater tendency to take advantage
of that cooperation. When a preprogrammed defection took place, the
security of total cooperation was broken, and S; went back to more co-
operation. The breakdown in security affected the choice of move dif-
ferently if defection took place in the first half or second half of the
sequence, and there was a different reaction for males and females.
Since there is an appreciable increase on each trial in the number
of Se defecting, it is reasonable to assume that there is a smaller de-
crease in the number of §s who defect early in the sequence rather than
later in the sequence. What is puzzling is the difference between males
and females in the behavior on the moves following the defection., Fe-
males cooperate more when the defection occurs early in the sequence.
They may take this as a warning that unless they cooperate, they'll
both receive low points; but when it happens later in the sequence,
they may feel it is an “unusual move” since there has been no other
previous defection. When it does not happen on the following move,
they revert back to their original strategy. Males have a different
pattern of behavior when responding to a programmed defection. When
the programmed defection occurs on the third trial, defection rates in-
crease to the previous level within three trials. When the defection
occurred later in thesequence, there were less defections for the rest
of the trials. if there were three or more trials after the defection,
males might have exhibited a similar strategy as when the defection oc-
curred earlier. They might be waiting three trials before they try a

defection strategy to see what their Opponent is doing. Thus, males,

 

33

more than females, might be waiting to see the strategy of their oppo-
nent before committing themselves to the risky move.)

One of the problems with this design was that each matrix should
have been tested with different payoffs to find one that would elicit
a greater amount of defection. This would have made for a more reli-
able analysis.

Another possible way to test the trust scale would be to ask the
Es to predict the other person's move and then allow him to play this
choice. This would give a clearer idea if trust is being ”overruled”

by the competition trait.

Ti ‘7?! r.— » me

1“. ~. (71'; 3.1.—

‘ 1

 

Summary

This study seems to indicate that personality does play a part in
choice of move in an experimental game though not in the way expected.
Whether this proves to be true in real life situations, where the stress
may be stronger and more realistic, only more research will show.

Another finding that needs further research is the differential
findings for men and women. The way the two sexes reacted in the triv-
ial trust game is something that bears further study. Why did one sex,
the males, find it a competitive situation while the females used trust
of others to decide their move. it should be remembered that while fe-
males conformed to the hypothesis and males did not, the definition of
the situation was made by a female. it just may be worth exploring the
idea that trust is defined by males and females differently. Since the
experiment was designed by a female, the matrix chosen may be one that
elicits trust only for women. Possibly, if the study were designed by
a man, different matrices would be chosen which would "work" for men.
The study shows some evidence of sex differences as other findings have,
but cannot offer an explanation that includes the other findings as well
as its own. There has been too little work to offer a consistent ex-

planation.

3h

fl
L
....”

 

.v — -
-.....—

- m In. a. 3'.‘¥tr&&n in A

LIST OF REFERENCES

LIST OF REFERENCES

Deutsch, M. Trust, trustworthiness and the F scale. Jodrnal of
Ahnormal'and‘Sogjal Psychology, l960,'§l, l380h0.

Grant, M., and Sermat, Y. Status and sex of other as determinants of
behavior in a mixed motive game. 'Jggrnal'Of'PerSOnaiity and
Social Psychology3 l969, 12, l5l-l57.

 

Halpin, S. M., and Pilisuk, M. Prediction and choice in the Prisoner's
Dilemma. Behavioral Science, l970, 12_(2), lh3-l53.

 

Holsti, 0. International politics and foreign policy. in Rosenau (ed.),
A reader in research_and theory. New York: Free Press of Glencoe,
l96l.

Komorita, S. Cooperative choice in a Prisoner's Dilemma Game. Journal
of Personality_and Social Psyghologx, l965, 2, 7hl-7h5.

Luce and Raiffa. Games and decision: 'lntrodUction and'criticalgsurvey.
John Wiley and’Sons: New York, l-ll.

LaForge, R., Leary, T., Naboisek, H. Coffey, N., and Freedman, M. The
interpersonal dimension of personality. J0urnal of Personality,
'95“: Zip 129-153-

 

Lutzke, D. R. internationallsm as a predictor of cooperative behavior.
Journal of Conflict Resolution, l960, fl, h26-h30.

Marlowe, D. Psychological needs and cooperation: Competition in a
two-person game. Psycholggjpal Reperts, l963, 13’ 364.

Marquis, Guetzkow, H. S., and Heyns. A social psychological study of
decision making conference. in Guetzkow, H. 5., Grou 5 Leader-
ship and Men. New York: Russell and Russell, l95l, 55-67.

No Clintock, C. G., Harrison, A., Strand, 5., and Gallo, P. internation-
alism-isolationism, strategy of the other player, and two-person

game behavior. Journal_of Abnormal and Social Psycholggx, l963.
61, 63l-636.

 

Mc Clintock, C. G., and Mc Neel, S. P. Reward and score feedback as
determinants of cooperative and competitive game behavior.
Journal of'Personalitypapd Social'Psychology, l966, £3 606-6l3.

35

36

O'Grady, P. Attribution of strategies in Prisoner's Dielmma Game: A
symbolic interaction approach. Unpublished Doctoral Dissertation.
Michigan State University, l970.

Rapoport and Chammah, A. M. Sex differences in factors contributing to
the level of cooperation in the Prisoner's Dilemma Game. Journal
of Personality and Social Psygholggy, l965, 2; 83l-838.

Rapoport, A., and Guyer, M. A taxonomy of 2 x 2 games. General Systems,
l966, Xl.

 

Terhune, K. W. Motives, situation and interpersonal conflict within
Prisoner's D] lema. ‘. Journal 'Of Personal ityjand 'So‘CIa'l Psychology,
l968, 8 (3), part 2, l-Zh.

Vinacke, W. E. Variables in eXperimentai games: Toward a field theory.
Psychological Bulletin. l969,IZl.(h), 293'3l8.

Wrightsman, L. S. Personality and attitudinal correlates of trusting
and trustworthy behaviors in a two-person game. Journal of
Personality and'Social'Psychology. l966, g, 328- .

APPENDIX A

LEARY'S lNTERPERSONAL CHECKLIST

Weights
z,

3
3

Weights
1,

WWW

lNTERPERSONAL CHECKLIST ITEMS BY SECTORS

A

Dictatorial

Bossy

Dominating

Manages others
Forceful

Good leader

Likes responsibility

Able to give orders

C

Cold and unfeeling
Thinks only of self
Shrewd and calculating
Selfish

Businesslike

Can be indifferent to
others

Likes to compete
with others

Able to take care of
self

37

Egotistlcal and conceited
Boastful .

Somewhat snobbish'

Proud and self-satisfied
independent

Self-confident
Self-reliant and assertive

Self-respecting

D

Cruel and unkind

Sarcastic

Self-seeking

impatient with others' mistakes
Stern but fair

Hard-boiled when necessary
Firm but just

Can be strict if necessary

Weights
z,

3
3

Weights

.8?

www

38

INTERFERSONAL CHECKLIST ITEMS BY SECTORS

E.

Hard-hearted
Frequently angry
Outspoken

Often unfriendly
irritable

Critical of others

Straightforward and
direct

Can be frank and
honest

.G.

Distrusts everybody
Jealous

Stubborn

Slow to forgive a wrong
Hard to impress
Frequently disappointed
Touchy and easily hurt

Able to doubt others

F

Rebels against everything
Bitter

Complaining

Resentful

Skeptical

Often gloomy

Resents being bossed

Can complain If necessary

H

Always ashamed of self
Timid

Self-punishing

Shy

Easily embarrassed
Lacks self-confidence
Apologetic

Able to criticize

Weights
z,

3
3

39

INTERPERSONAL CHECKLIST iTEMS BY SECTORS

Spineless
Meek

Passive and
unaggressive

Obeys too willingly
Easily led

Modest

Easily gives in

Can be obedient

K
Will believe anyone

Easily fooled

Likes to be taken
care of

Lets others make
decisions

Accepts advice
readily

Very anxious to be
approved of

Trusting and eager
to please

Appreciative

J

Clinging vine
Hardly ever talks back

Dependent

Wants to be led

Admires and imitates others
Often helped by others

Very respectful to authority

Grateful

L

Agrees with everyone
Wants everyone's love

Will confide in anyone

Too easily influenced by friends
Wants everyone to like him
Always agreeable and pleasant
Eager to get along with others

Cooperative

Weights
h

3
3

#0

iNTERPERSONAL CHECKLIST ITEMS BY SECTORS

M

Loves everyone
Fond of everyone
Likes everybody

Friendly all of the
time

Warm

Sociable and
neighborly

Affectionate and
understanding

Friendly

0

Spoils people with
kindness

Overprotective
Generous to a fault

Too willing to give
to others

Big-hearted and
unselfish

Enjoys taking care
of others

Good leader

Helpful

N

Tries to comfort everyone
Oversympathetic
Forgives anything

Too lenient with others

Encouraging of others

Tender and soft-hearted

Kind and reassuring.

Considerate

P

Expects everyone to admire him

Tries to be too successful
Acts Important

Always giving advice

Often admired

Makes a good impression

Respected by others

Well thought of

APPENDIX B

INSTRUCTIONS

instructions

You are going to play a game which will enable you to win a cer-
tain amount of money. This amount will not be determined by only you.
But rather, the amount won by you and your partner will depend on what
move each of you makes. The sum of the amount earned in all games you
will play will be your pay for participating.

There are 4 people who are participating in this research at this
moment. Each of you will play a number of different games with differ-
ent pe0ple. You will not know who you are playing at each game. You
will not be able to see or talk to your partner.

You will be asked questions throughout this session. Please
answer yes or no. Yes will be the [left or righgj button in front of
the screen. The question will be ... is there a slide on the screen
in front of you. Please answer yes or no. (The light in front of you
will go on, when you are supposed to answer. This will be called the
ready light from now on.) ‘The game is played as followszv

You will notice on the screen In front of you a chart consisting
of four squares each of which will be called a cell. Each of these
cells contains the possible points which you or your partner can earn
for any game. In each game, there are four possible sets of points
that you and the other person can earn. Your points will be the ones
in the red shaded part of each cell, the clear area in the same cell
will be the other player‘s points. These points will be converted into
money at the end of these sessions at Be a point.

The cell that is selected will be determined by which column you
choose and which row your partner chooses in the following manner. You

may chose either the column on the left (i) or the column on the right

4i

#2

(2). You indicate your choice by pressing the button that before was
indicating yes or no. Now it means left column, left button and the
right column, right button. Your partner at the same time chooses
either the upper row (i) or the lower row (2). if you chose column i,
you push the left button, then your points are read from the left hand
squares. You will get either 3 points or i point, depending upon which
row your partner chooses. If he chooses row i, then you will get 3
points, while he will get A. if he chooses row 2, you both will get i.

If you had chosen column 2, the right button, you would have read
either i point or A points. If your partner chose i, you both would
have read i. If he had chosen row 2 while you had chosen column 2, you
would have read A, while he got 3.

When you have made your decision on which column to pick for a
given trial, press the button under the column of your choice. Do not
make a choice until the right light is on.

An easy way to understand this is to draw an imaginary line through
your choice (column i or 2), and an imaginary line through the other
person's possible choices. Where these meet, is the square that deter-
mines your pay. Remember the amount of points that you receive is in
the red shaded area, while your opponent's points are in the clear area.

All of you are responding by making column choices, but your part-
ner's chart is reversed, so that their chart is the equivalent of being
your rows. Our equipment records the choices, and calculates the appro-
priate scores.

i will ask questions to make sure that you understand the slide.
This is just the instruction slide...questions....

This is the first game that you will play...l'm going to give you

#3

an example of the different choices that you may make. Tell me if it is
correct or not by answering yes or no. Do not make your decision until
i tell you it is a decision trial and the ready light for that trial

is on.

Questions

See Figure 5: ~instrUCtion Slide.

l. You chose the right hand column and your partner chose the upper
row, you both get i. Yes or no.

2. You chose the left hand column and your partner chose the upper
row, you get 3 and your partner gets 4. Yes or no.

3. You chose the right hand column and your partner chose the
bottom row, you get A and your partner gets 3. Yes or no.

A. You chose the left hand column and your partner chose the
bottom row, you both get i. Yes or no.

See Figure 3.

l. Did your slide change. Yes or no. i am going to ask you a few
questions to make sure you understand this slide.

2. You chose the left hand column and your partner chose the upper
row, you both get 5. Yes or no.

3. You chose the right hand column and your partner chose the upper
row, you get A and your partner gets 0. Yes or no.

A. You chose the right hand column and your partner chose the
bottom row, you both get 5. Yes or no.

5. You chose the left hand column and your partner chose the
bottom row, you both get i. Yes or no.

Make your decision by pressing the button under the column of your
choice when the ready light goes on.

Ah

See Figure A.

i will now ask a few questions about the slide to make sure that
you understand it.

i. Did your slide change. Yes or no.

2. You Chose the right hand column and your partner chose the
upper row, you both get I. Yes or no.

3. You chose the left hand column and your partner chose the
Upper row, you both get 2. Yes or no.

A. You chose the left hand column and your partner chose the
bottom row, you get 4 and your partner gets 0. Yes or no.

5. You chose the right hand column and your partner chose the
bottom row, you both get 2. Yes or no.

Make your decision now and indicate it by pushing the button under
the column of your choice when the ready light goes on.
See Figure l.
l. Has your slide changed. Yes or no.

2. You chose the left hand column and your partner chose the
upper row, you both get 3. Yes or no.

3. You chose the right hand column and your partner chose the
upper row, you get A and your partner gets 2. Yes or no.

A. You chose the right hand column and your partner chose the
bottom row, you both get I. Yes or no.

5. You chose the left hand column and your partner chose the
bottom row, you get 2 and your partner gets A. Yes or no.

Make your decision now and indicate it by pushing the button under
the column of your choice when the ready light goes on.

We are now going to have a slightly different procedure. You are
going to see the same slide for the next trials, but you are now going
to receive information about how much money you are earning. Remember
each trial will be with a different person and you will be getting 5¢

a point.

45

The way you will receive this information is by the four lights
outside the screen. One will go on to indicate which cell you are in.
If you had chosen the right column and your partner chose the upper
row, the light by the upper right hand corner will go on, since you are
in the upper right hand cell.

if the other person had chosen the bottom row and you had stayed
in the same cell, the light In the lower right hand side would go on,
since you are in the bottom right hand cell.

Another way to look at this is that the light that goes on indi-
cates the cell that you have chosen by being in the same position as
the cell. 3

Remember your points will be in the shaded area of the correspond-
ing cell.

The sequence of events will be: a ready light will go on; you will
make your decision; one of the four lights will go on to indicate which
cell you are in; the ready light will go on again and you will make
your decision; then one of the four lights will go on to indicate which

cell you are in. This will continue until the end of the session.

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