Simply stated, personality refers to a person's style of interacting with the
environment, especially the social environment. Personality is often considered to be
relatively stable across time and from situation to situation.
Unlike states (which are considered to be temporary, such as hunger or thirst), a
trait is a relatively stable tendency to behave in a certain way. Although the trait may
require some environmental trigger to release the behavior, the trait is considered to be part
of the person, not the environment. For example, a person who has the trait of high
aggressiveness probably behaves aggressively only in certain situations, situations in which
less aggressive persons do not show aggressive behavior.
Traits are generally considered to be continuously distributed, not all or nothing
characteristics. You and I may both be aggressive, but you more so than I.
The goal of trait theories to construct a relatively small number of personality
dimensions that is useful for summarizing the differences between individuals.
Gordon Allport, one of the major figures in the study of personality, found that the
English language contains at least 18,000 words that describe personality characteristics.
For example, consider these: Friendly, agreeable, amiable, cordial, kind, sociable,
warmhearted. Clearly we need to reduce the number of words in our vocabulary of
Surface Traits are those that are inferred from individual differences in specific
behaviors. To identify surface traits, personality researchers collect data on a large number
of behaviors from a large number of persons and use statistical techniques to identify
clusters of behaviors that correlate well with one another within each cluster.
Central Traits are those which are inferred from surface traits. Statistical
techniques are employed to identify clusters of surface traits that correlate well with one
another but not with the surface traits in other clusters.
The hierarchical nature of specific behaviors, surface traits, and central traits is
illustrated in Gray's Figure 15.1.
Can you describe specific behavior that might be included in the surface cluster
"pugnaciousness" (prone to physical fighting) or "competitiveness?"
Do note that the inclusion of "argumentativeness," "pugnaciousness," and
"competitiveness" under the central trait of "aggressiveness" is based on empirical
grounds -- if our research were to find that there is not a good correlation between verbally
sparring and physically sparring, then those two surface traits would not be included in the
same central trait.
Raymond Cattell developed a personality questionnaire called the 16 PF. Cattell
reduced the 18,000 personality adjectives in English to about 170 surface traits and then
clustered these into 16 Personality Factors (central traits). A person taking this
questionnaire responds "yes, occasionally, or no" to about 200 statements such as "I like to
go to parties." From these responses, a score is computed for each of the 16 central traits.
Hans Eysenck developed a model in which there are only three central traits:
Introversion - Extroversion: Introverts try to avoid (social) stimulation while
extroverts seek it.
Neuroticism - Stability: Neurotics get emotionally upset and thus are moody,
anxious, impatient, etc.
Psychoticism - Nonpsychotism: Psychotics are aggressive and lack concern
The Big Five Theory proposes the following five central traits:
Introversion - Extroversion: As above
Neuroticism - Stability: As above
Openness to Experience - Nonopenness: Open folks are imaginative,
independent, curious, interested in many things, etc.
Agreeableness - Antagonism: Being courteous, selfless, trusting, and
cooperative going along with agreeableness
Conscientiousness - Undirectedness: The conscientious are careful, reliable,
diligent, ambitious, etc.
Stability of Traits. The research here involves testing the personality of many
people at various times throughout their lives. These measurements may involve the
subjects taking personality tests and/or may involve having others rate the subjects'
personalities. The Big Five traits are remarkably stable across time, at least after the age
of about 30. Correlations between one administration and another run between .50 and
.70, even when there are many years (30 or more) between measurements, and even
when the persons rating the subjects differ between one time and the other.
Maturation. There are some common changes with increasing age. For example,
as we get older we tend to get less neurotic (thankfully!), less extroverted, less open to
experience, more conscientious, and more agreeable.
Predicting Behavior. There is considerable evidence that knowing an individual's
personality test scores helps us predict his or her behavior. For example, persons who
score high on Extroversion are, compared to introverts, less disturbed by intense stimuli,
more likely to choose to live and work with many people, more adventuresome in their
sexual behaviors, more likely to look a person in the eye when speaking with em, and more
likely to talk a lot at group meetings.
Sometimes we can even predict adult behavior from personality tests given during
childhood. For example, children who were at age 3 identified as having low self-control
were, at age 21, more likely to have been fired from a job or convicted of a crime.
We should keep in mind that individual differences in personality may often be
masked by social forces. In a familiar social situation, persons all acting in the same
social role may all act pretty much the same -- but observe them in a novel, ambiguous, or
stressful situation and individual differences related to personality are likely to emerge.
Walter Mischel has argued that we could predict behavior much better if we
measured situation specific dispositions rather than global traits. Mischel et al.
observed, repeatedly, 19 different types of behavior which would reasonably be considered
to be related to the global characteristic of conscientiousness. They found high
consistency within each of these 19 different types of behavior but much lower
consistency across categories. For example, a student who was likely to prepare very
neat notes for one class was also likely to do the same for e's other classes, but that
student was not much more likely than average to keep e's bed nicely made every day.
The Physiology of Personality. Individual differences in central traits can be
related to individual differences in physiology. For example, Eysenck suggested that the
brains of introverts are more easily aroused than those of extroverts. He also
suggested that all persons try to achieve an optimal level of arousal. Accordingly, to
achieve such an optimal level of arousal introverts would be expected to avoid highly
stimulating environments while extroverts would be expected to seek great stimulation.
Evidence supporting Eysenck's suggestions include the following:
Introverts outperform extroverts on tasks that require focused concentration in
situations where there is little stimulation.
Extroverts do better in tasks that require attending to many stimuli in an arousing
Introverts show a greater physiological response to a sudden noise
Introverts' performance on a learning task is more affected by a distracting noise
than is extroverts' performance.
Introverts are less tolerant of painful electric shock than are extroverts.
In a quiet situation, PET scans show that the frontal lobes of introverts are more
active than are those of extroverts.
A stimulant drug (caffeine) worsened performance on a learning task for introverts,
but facilitated performance for extroverts.
And introverts even salivate more when lemon juice is squired in their mouths than
The Genetics of Personality. There is considerable evidence of heritability of
personality traits. For example, identical twins (even when reared apart) are much more
similar in personality than are fraternal twins. For most traits that have been evaluated,
including all of the Big Five, heritability estimates range from about .40 to about .50.
Heritability has even been found to be high in traits that one would think are greatly
influenced by environmental factors. Consider Traditionalism (conservative values and
respect for discipline and authority), for example -- heritability for this characteristic has
been estimated to be about .60. As another example, the heritability of one's attitude
about the death penalty has been estimated to be about .50.
I expect that most genetic effects on personality are polygenic rather than resulting
from the action of a single gene. There is, however, some evidence of single gene
effects. For example, there is a significant relationship between neuroticism and the
presence of a singe allele that increases the action of serotonin. Likewise, there is a
significant relationship between the trait of novelty seeking (impulsiveness, excitability,
and extravagance) and another single allele, one that decreases the action of dopamine.
Ultimate Explanations of Individual Differences in Personality
Why are there individual differences in personality?
Why hasn‟t natural selection simply given us all the one best set of personality traits?
Even in many nonhuman animals, there is considerable diversity in behavioral styles.
What is the adaptive value of such diversity?
Diversified Investment. One answer to these questions has to do with a parental
strategy that is similar to diversification in one‟s investment portfolio. As you are no doubt
aware, at any given time some investments will do very well, some investment so-so, and
others will do very poorly. At other times the investments that did poorly at an earlier date
might do marvelously, and those that did well earlier might do poorly later. If you put all of
your assets into one type of investment, you risk loosing it all during a time when that type
of investment crashes and burns. On the other hand, if you diversify your investments,
then you greatly reduce your risk of loosing it all.
From the genetic perspective, producing offspring is an investment in the future.
If those offspring prosper and multiply, our genes live on. If those offspring crash and
burn, our genes disappear. If our environment were unchanging, it might be possible to
construct the perfect personality for that environment. In that case, the best strategy
would be to produce only offspring with that perfect personality. But our environment is
not constant. When our environment is constantly changing, the perfect personality is
a moving target. If we were to give all our children the wrong personality for the
environment in which they will reach reproductive age, then we might loose all. A safer
strategy might be to diversify our investment by producing children with a variety of
personalities. In that way, it is more likely that at least some of them will survive and thrive,
those who happen to have the personalities best to take advantage of the environment as it
is when they mature.
Filling Different Niches. A niche is a role that an organism can adopt in a
dynamic biological system. In a typical biological system there is a variety of different
niches. Each niche has a limited capacity -- that is, it can support only so many
individuals living in that niche. Genetic diversity among organisms may allow them better
to exploit all the possible niches in an environment. This may be true even within a
single species. Gray uses the example of pumpkinseed sunfish. One niche available to
them is to stick close to the shore, hiding among the vegetation there, and not moving
about much. A quite different niche also exploited by these fish is that in the open water,
where the fish who does not move about quickly will be eaten by predators.
Pumpkinseeds that occupy these different niches tend to differ on both physical and
behavioral characteristics. Diversity in the species allows it to be more successful in
exploiting the environment, with some individuals specialized for the one niche, while
other individuals are specialized for the other niche.
The environments of humans (including their social environments) provide them
with a multitude of niches to be filled. It is almost certain that the best personality to fill
one niche is different from the best personality to fill a different niche. Accordingly,
producing humans with diversity of personalities may enable our species to more
successfully exploit its environment.
Intra-familiar Diversity. If we compare the personalities of individuals who live in
the same family, we find that they are not much more similar than are equally related
individuals who live in different families. For example, the correlation between the
personalities of brothers that live in the same family is about the same as that of brothers
who have been reared apart. Some have interpreted this to mean that the family has little
effect on personality development, other than by the sharing of genes.
Others have pointed out that siblings raised in the same family do not really share
identical environments. Family environments change with time. For example,
consider my family. I was born in to a family that was, in many ways, a typical working
class family, lower middle class. My father who worked in a glass factory, received a lot of
promotions during his lifetime, which caused a considerable change in the family
environment across the years. By the time my younger brother was born ten years later,
our family was solidly middle executive class. After I left home to make my own life, my
younger siblings moved with my parents to Paris, where my father headed the European
division of Corning Glass Works. This was an environment totally foreign to me. In many
ways they were raised in a family quite different from that in which I was raised.
Sibling Diversity. Within a single family with two or more children, there may be
additional factors that promote diversity in personality. Consciously or unconsciously, both
children and parents may act in ways that increase diversity in personality among the
children within a family. If all the children try to fill the same niche, then sibling rivalry
may become dangerously high. If each child can find a niche that is his or hers alone to
exploit, then there is likely to be less competition among siblings and each child can the
best within e‟s own niche.
Birth Order. Clearly the family environment for first born children would be
expected to be different from that of later born children. There have been many studies of
the effect of birth order on personality and other characteristics. In my opinion, the
demonstrated effects of birth order have been neither clear nor large.
Gray discusses Frank Sulloway‟s research on effects of birth order. He argues
that first-borns are, for a while, the only child in the family, and this leads them to identify
with the parents, to fill the niche that the parents most support. As a result, first-borns
tends to be more conscientious, achievement oriented, conservative, traditional, and
respectful of authority than are later-borns. Later born children cannot compete effectively
within the niche that the first born has exploited, so they must carve out their own niches,
adopting alternative roles in which they can excel. This causes later-borns to be more
open to new experiences and more friendly than first-borns.
Gender Differences. Women score, on average, about one standard deviation
higher than men on measures of friendliness. This is considered to be a very large
difference, equivalent in magnitude to a 200 point difference in total SAT score. This
gender difference is found across cultures. Women also tend to score higher on
measures of anxiety and conscientiousness, but the magnitude of these differences is
considerably smaller. Men score higher on measures of sensation seeking, although the
difference between men and women tends to decline with age.
Gender, Personality, and Life Satisfaction. Persons whose personality is
atypical for members of their gender are likely to be less satisfied with life than are those
who fit the stereotype. For example, young men who are shy tend to be emotionally
distressed and unhappy, but there is no such association between shyness and
unhappiness in young women. Likewise, women who have competitive personalities
tend to have low self-esteem, but in men competitiveness is associated with high self-
Natural Selection and Gender Differences. One can argue that men and women
have faced different reproductive challenges over many generations, and that natural
selection has accordingly equipped men and women with different personalities, each best
suited to the type of challenges typically encountered by gender-mates. For example,
women are specially equipped (with breasts) to take care of infants, and accordingly they
are also equipped with traits of nurturance, cooperation, and caution. Men, on the other
hand, have had to compete with one another for access to women and other reproductive
resources, and accordingly they have been equipped with traits of competitiveness,
aggressiveness, and risk-taking. There even appears to be a hormonal basis for sex
differences in personality, with oxytocin causing greater friendliness in women and
testosterone causing greater aggressiveness in men.
Culture and Gender Differences. An opposing viewpoint is that culture has been
a greater force than natural selection in the shaping of gender differences in personality.
According to this theory, biological differences between the sexes may have shaped
different cultural expectations for men and women very early in our species‟ history, with
these cultural expectations then causing even greater differences between men and
women. Across the generations these gender differences caused by cultural expectations
may have become greater and greater, by a sort of positive feedback loop -- when men
and women differ in personality, that reinforces the cultural expectation of gender
differences, which may create even greater gender differences, and so on.
Gender versus Sex. These days it can be confusing to know when to use the term
“gender” and when to use “sex.” In general, it is appropriate to use the term “sex” when
referring to characteristics that are more influenced by biology and “gender” when referring
to characteristics that are more influenced by culture. It is not, however, always very clear
to me whether a particular characteristic really is more influenced by culture than by
biology or vice versa. See my document Sex/Gender/Whatever for more on this.
These theories emphasize the role of mental forces in determining personality.
The founding father of these theories was Sigmund Freud. Freud was not a
psychologist. He was a medical doctor practicing in Vienna, Austria in the late 1800‟s.
Freud came to believe that many of the problems which his patients presented were not
caused by diseases of the body but rather by mental conflicts.
Freud theorized that the most basic instincts or drives of humans are related to sex
(eros) and death or aggression (thanatos). These drives live in the unconscious id.
Is his native German, the word Freud used was "es," which means "it" -- that animal thing
down there that drives me towards eros and thanatos. When translated to English,
somebody decided to use the term "id" instead. I guess the third person generic pronoun
was just not mysterious enough for the translator. The id's eros and thanatos motivate us
to think about and even act out behaviors that are socially unacceptable. If these bad
thoughts from the id break through to consciousness, they make us anxious.
Accordingly, he conscious part of our mind needs somehow to manage to keep id-
motivated thoughts from breaking through to consciousness. We employ a variety of ego
defense mechanisms for that purpose. The ego ("ich" in the original German, which
means "I"). While the id operates on the "pleasure principle" (do what feels good and do it
now regardless of any consequences, the ego operates on the "reality principle" (try to
satisfy the id in ways that not destructive to the self and society). A third part of the mind,
not mentioned by Gray, is the superego ("uber ich" in the original German), which
operates according to the morality principle -- it makes us feel bad when we behave
contrary to accepted norms.
According to Freud, individual differences in personality are caused by
differences in our unconscious motives, how they are manifested, and how we defend
Repression is the most basic of the ego defense mechanisms. It operates by
putting up mental barriers to prevent socially undesirable thoughts from entering
consciousness. This is done without our awareness of the construction of barriers. But
these barriers are not perfect. Bad thoughts may slip through. When they do, we employ
other ego defense mechanisms to distort those bad thoughts in ways that make them
seem not so bad. I shall discuss only a few of the more common ego defense
Suppression involves the conscious avoidance of thinking about unpleasant
things. This differs from repression in that we are aware that we are erecting barrier to the
Projection involves our attributing the undesirable motives or characteristics to
others rather than to ourselves. As an example of projection, consider research done by
Robert Sears. He asked fraternity members to rate themselves and their fraternity
brothers on various characteristics, such as stinginess. He found that men who were
rated as high in such a characteristic but who denied having it themselves tended to rate
their brothers as high in that characteristic -- projecting their own characteristics onto
Reaction Formation is when we turn a bad thought or motive into its good opposite
thought or motive. As an example, consider homophobia, the irrational fear and hatred of
homosexuals. It has been argued that homophobia results from a reaction formation --
that is, persons who have unconscious desires to engage in homosexual activity become
very anxious about that when these desires start leaking into consciousness, so they think
very contrary thoughts. One research study testing this hypothesis measured male
subjects‟ homophobia (by a questionnaire) and then directly measured engorgement of
their penises while they were watching videos of men engaging in homosexual activities.
Despite admitting to feeling any arousal while watching such videos, homophobic men’s
penises became significantly more aroused than then those of non-homophobic men.
Displacement occurs when the energy from a bad desire is redirected to an
acceptable behavior. For example, the boy whose id wants to kill his father (to remove
the primary rival for his mother‟s love) may displace the energy from that bad motive into
boxing, football, or rugby. Interestingly, the basic idea of displacement is also found in
some theories of nonhuman animal behavior -- for example, an animal who really wants
to bite his rival may funnel that energy into less dangerous behaviors, such as grooming
itself or pawing the earth repeatedly.
Sublimation is just a special case of displacement in which the substitute activity is
not only acceptable but also highly meritorious. For example, a man with the id of Jack
the Ripper might become a first-rate surgeon.
Rationalization is my favorite sort of defense mechanism. Here we come up with
socially acceptable reasons for our behavior or our thoughts, but they are not the real
reasons. For example, I convince myself that my great interest in the study of sexual
behaviors is because I am a scientist interested in the effects of natural selection on
behavior, and reproductive behaviors are those which are most likely to be greatly affected
by natural selection. Yeah, sure -- that is what I say, even what I think myself, but the truth
is to be found in my horny id!
I should note that there are other psychodynamic theories that do not
hypothesize that sex and aggression are the most basic human drives. Karen Horney
emphasized the drive for security, stemming from the child‟s dependence on its parents
for survival. Alfred Adler stressed the drive to achieve. Object Relations Theorists
stress the conflicting drives of attachment versus autonomy.
I should also note that all of these psychodynamic theories suppose that the first
few years in life are the most critical years for the formation of one‟s personality.
These theories suppose that it is learned beliefs and habits that shape one‟s
personality. Here to there may be unconscious elements, but here they are not from
repressed bad motives but rather from habits that have been practiced so much that
they become automatic, executing without consciousness. Some psychologists even
argue that the majority of human behavior is controlled by such unconscious learned
habits. For example, when I drive to work, I don‟t think about what I am doing -- I am on
auto pilot, I think about other things, but my unconscious does the driving. Likewise,
when you interact socially with others, you don‟t have time to stop and think about every
thing to say -- you are on automatic pilot there too. Sometimes you may later ask yourself
“What was I thinking when I said „so and so.‟” The truth is, you weren‟t thinking at all,
you were on auto-pilot!
Julian Rotter was a pioneer in the development of social/cognitive theories of
personality. He is best known for his work on Locus of Control. The basic idea here is
that individuals have different beliefs with respect to the extent to which they are in control
of the rewards that they get or don‟t get in life. The person with an external locus of
control believes that it is mostly luck and the influence of powerful others that control
whether you get rewards or not. Persons with an internal locus of control believes that
they themselves control whether they get rewards or not, through their ability and their
effort. There is considerable evidence that persons with an internal locus of control are
more likely to take charge of their lives and be less anxious and more content with life than
are those with an external locus of control, but the effects of locus of control are often
not very impressive in magnitude. Rosina Chia and two of her colleagues in our
department have conducted numerous research projects involving locus of control, both in
this country and several other countries.
My first exposure to Rotter‟s locus of control instrument was as a freshman at
Corning (NY) Community College. I had just gotten out of the military and was going
through all these moronic activities for freshman orientation. One of the things they did
was to sit us down and make us fill out some questionnaires. One of them was Rotter‟s
scale. I hated it, because of its forced-choice format (see Table 15.3 on page 600 of
our text for some example items). On nearly every item I thought “how can I choose one of
these two extreme alternatives, the truth is somewhere in between.” Well, a couple of
weeks later I was asked to see one of the school psychologists. He explained that they
had reason to believe that I was doomed to failure at school unless I got some
counseling. He did not tell me how he knew my fate, but I later learned it was because I
scored extremely external on Rotter‟s scale -- duh, I just got out of the military, where it
seemed like some Arschloch (that is German for “powerful other”) was telling me what to
do every minute.
Well, external that I was, I consented to the counseling when asked to do it by a
powerful other. Near the end of the semester the psychologist asked me to fill out a
questionnaire. It was Rotter’s scale, again. I asked if this was the same questionnaire
that I had filled out during freshman orientation. He said “yes.” I said that I had the feeling
that he wanted me to answer these questions quite differently than I had during freshman
orientation and I asked him if that were true. Without saying “yes,” he indicated that I was
correct. Again, being the true external that I was, I consented to his request and scored
highly internal. He was happy, especially since I had very high grades that semester. I
gave him data that suggested that his program of counseling was effective in modifying
the locus of control of external students who would otherwise have failed in school.
Philosophically I am still very much external in locus of control. I am a strict
determinist, one who thinks that nothing happens without a cause -- and ultimately the
causes of every action one takes, every thought one has, and every decision one makes
can be traced to events that have taken place outside of one self. I have argued earlier
that I think that “free will” is a delusion, but a useful one, one that makes it more likely
that the individual will try to take charge of his or her life and make something out of it.
Albert Bandura stressed individuals‟ self-efficacy, their beliefs about their ability
(or lack of ability) to accomplish specific tasks. This sounds a lot like Rotter‟s locus of
control, but it differs in you can think that you are quite able to accomplish some specific
task but not think that doing so will necessarily bring you rewards. For example, you might
have very high self-efficacy with respect to doing college work but an external locus of
control with respect to being able to get a good, satisfying job after graduation -- after all,
who know what the economy will be like then, how lucky you will be in your job search,
what powerful others may help or hinder you, and so on.
Research on the topic of self-efficacy indicates that thinking that you can
accomplish some task may actually help you accomplish the task. After all, if you are not
capable of doing it, why waste your time trying? Both parents and teachers might be
more successful at their jobs if they were to spend a little time convincing their children
and their students that they are capable persons.
Optimism vs Pessimism. I have often said that pessimism is the better strategy
because the pessimist is either going have the satisfaction of seeing that he is right or will
be pleasantly surprised that he was wrong. I, however, am the sort of pessimist who
expects things to go bad, but who works very hard to try to prevent that from
happening. There is no doubt that I have paid for that by suffering more from anxiety
than I would if I were an optimist, but my pessimism has not prevented me from leading a
very productive life. Pessimism can be counterproductive, however, in those who decide
that there is no sense in even trying if everything is bound to go wrong. Optimism may
motivate one to take charge and work hard, but in some it can be counterproductive -- the
person who thinks that nothing bad can come to him (Alfred E. Newman‟s “What, me
worry?”) is likely to act in ways that increase the chances that bad things will come to
These theories stress the uniquely human (or so we think) ability to perceive
ourselves as apart from the rest of the world. I happen to think that we share this
ability with some other animals, but this is not the time for that discussion.
Humanists speak of one‟s “phenomenological reality.” This phrase refers to an
individual‟s conception of self and world. Similar to Kantian transcendentalism, the
notion of a phenomenological reality may include a recognition that we cannot be directly
aware of any concrete reality, that “reality” in human experience is a mental event and a
very personal thing, something that we each construct from our sensory and social
experiences. Our personalities differ because we have constructed different
phenomenological realities. Kant might add that they don‟t differ all that much, because
we all have common intuitions (Anschauungen).
Carl Rogers stressed the role of self-concept. His patients seemed to obsessed
with “finding their true selves” and “becoming their true selves.” Whether this is
something common to humans or just common to the sort of clients who sought treatment
to Rogers can be disputed. In any case, Rogers argued that when people find their
true selves (or are deluded into thinking they have), they are happier and more
productive, felling like they are in charge of their lives rather than being told what to do by
others. Hmmm, sounds a bit like locus of control and the delusion of free will, doesn‟t it?
Abraham Maslow stressed the importance of “self-actualization” as the highest
level need in a hierarchy of human needs, from the very basic (like having enough to
eat and drink, shelter from the elements and predators), to the nice (being loved and
feeling good about oneself), to the ultimate achievement of self-actualization in which
one has become all he can and is at one with the world. Maslow argued that the needs
lower in the hierarchy must be satisfied before one is motivated to achieve the higher level
needs. This always makes me think of the starving artist or musician who sacrifices his
or her basic needs in exchange for opportunities to excel artistically.
Cultural Relativity of Personality Theories
All of the theories we have discussed were created by, and validated with, Western
European or North American people. Do they do an adequate job of describing and
explaining individual differences in personality in persons from other cultures? There is
some evidence that they do not. Those interested in this question are encouraged to
check out the literature in cross-cultural psychology.
Revised March, 2006. Illustrations now have alternative text.
Back to the PSYC 1000 Lecture Notes Page