theories of personality

1. Chairperson G. Anupma
Dr A.Ravi & Dr K.Veer
VIMHANS
Vijayawada

2. What is personality..?
the enduring or lasting patterns of behavior and thought
(across time and situation).
‘”dynamic organization within the individual of those
psychophysical systems that determine his/her unique
adjustment to his/her environment.” (Allport)

3. Personality theories
Type and Trait approaches
Psychodynamic approaches
Learning and Behavioral approaches
Humanistic approaches.

4. personality theories:
1. Trait : Alport and Cartell
2. Psychodynamic theory: Sigmund Freud
The Neo-Freudians:
3. Carl Jung: Analytical psychology
4. Alfred Adler: Individual psychology
5. Karen Horney: Feminine psychology

5. Type theories
Focuses on the people’s personal characteristics.
One of the first type theories was proposed by
Hippocrates, he divided people into 4 types
SANGUINE – cheerful,confidently optimistic
MELANCHOLIC – depressed, morose
CHOLERIC – short tempered
PHLEGMETIC –slow moving, calm,unexcitable

6. Type is simply a class of individuals said to share a
common collection of characteristics.e.g.
Introverts –shy,social withdrawal and tendency not
to talk much
Extroverts – outgoing ,friendly and talkative

7. Trait theory uses two different methods of research:
Idiographic approach: defines traits by studying
individuals in depth and focuses on the
distinctive qualities of their personalities (Gordon
Allport)
Nomothetic approach: studies groups of people
in the attempt to identify personality traits that
tend to appear in clusters. This approach uses the
statistical technique called factor analysis
(Raymond Cattell)

8. 1. Trait theory.
Gordon Allport. Considered patterns of traits to
be the unique attributes of individuals.
Allport conducted thorough and detailed studies
of individuals in depth, often through long-term
case studies.
His idiographic research led him to conclude
that all people have certain traits, or dispositions,
that are the building blocks of personality (1937,
1961, 1965, 1966).
Can you think of some of the traits that are
unique attributes of who you are?

9. Examples of Individual traits
- Honesty
- Kindness
- Compassion
- Courage
- Loyalty
- Responsible
- Social
- Talkative
- Sensitive

10. Allport described three different types of traits:
1. Cardinal traits: Traits that are so much a part of
who the person is, you can define the person by the trait
(e.g. – Honest Abe Lincoln)
2. Central traits: Major characteristics of our
personality such as: sensitivity, honesty, and generosity.
These traits are quite generalized and enduring, and it is
these traits that form the building blocks of our
personality. Allport found that most people could be
characterized by a fairly small number of central traits
(usually five to ten).
3. Secondary traits: less generalized and far less
enduring traits that affect our behaviors in specific
circumstances. Examples include our dress style
preferences.

12. Trait theory.
Hans Eysenck (1906-1997). Disagreed with Allport and
Cattell. He believed that there are only two major
dimensions to personality:
1. Intraversion-Extraversion
2. Neuroticism-Stability

14. Problems with trait theory:
- Circular reasoning: Which comes
first the behavior, or the trait?
- Lack of situational consistency
(Mischel)
- No explanation for what causes
these many different traits to occur
- Lack of agreement on the number
and type of traits

15. Psychodynamic approaches
Emphasize on ongoing interactions among motives ,
impulses and psychological process.

16. Sigmund Freud MD (neurologist)
Psychodynamic Theory
Vienna, Austria (1856-1939).
Techniques used: hypnosis, catharsis, dream-
analysis, free-association, parapraxes
Freudian slips or parapraxes – everything we do
and say, even by accident, has hidden meaning
Believed in the importance of the “unconscious”
mind

17. “unconscious” forces are animalistic
sexual/aggressive drives that motivate most of
human behavior
These “unconscious” drives operate without
conscious awareness. This is because our
unconscious desires are too difficult or too painful
to face directly
Freud referred to these unconscious motives
collectively as the “id”
Freud believed there is a reason behind
everything we do

18. Personality structure
The three major forces of the psyche are the:
1. Id = unconscious = pleasure principle
- Primary process thinking: wish fulfillment
- Thanatos – aggressive /Eros - sexual
- I want it now! Instant gratification
- Are we an id driven society?
- Part of the iceberg that is submerged underwater
2. Ego = conscious = reality principle
- What are the real-world consequences of my actions?
- secondary process thinking: reality testing
- part of the iceberg that is above water and aware of reality
3. Superego = preconscious = morality principle
- What is the proper way to behave? Mom/Dad/Society
- Ego-ideal: shoulds
- Conscience: should nots
- Part of the iceberg that is just under the water but can sometimes surface

19. Chapter 3 - Personality

20. How would the id, ego, and superego respond to the
following dilemma?
Should you go out with your
friends to a great party, or
should you stay home and
study for your psychology
exam tomorrow?

21. Freud’s psychodynamic theory can be summed up quite
nicely with the visual image of a driver and a horse-drawn
carriage with two horses.
- Imagine the horse on the right is called “Id” and keeps
pulling to the right to go down Pleasure Road
- The horse on the left is called “Superego” and keeps
pulling to the left to go down Morality Way.
- The drivers name is “ego” and his job is to keep both
horses traveling straight ahead on the road called Reality.

22. Freud’s Psychosexual Stages.
- According to Freud, as we age, different parts of
the body are used to fuel the id with pleasure
(libido = energy source).
1. Birth – 1 ½ years: Oral stage
gratification is gained by oral stimulation
(Breastfeeding).
2. 1 ½ - 3 years old: Anal stage
pleasure is gained by being able to
control feces. (Potty-training)

23. 3. 3 – 6 years old: Phallic stage: awakening of sexuality
a. Oedipus complex for boys: when a male child wants to kill his
father so he can have sex with his mother. (from the Greek tragedy
“Oedipus Rex” by Sophocoles)
- Freud believed boys would eventually overcome this conflict by
identifying and bonding with the father.
b. Electra complex for girls: girls are jealous because they don’t
have a penis, and they really want one (from Greek myth of
“Electra” who plotted with her brother “Orestes” to kill their
mother “Clytemnestra”).

24. 4. 6-12 years old: Latency stage
pleasure is gained through same-sex peer
friendships
5. 12+ years old: Genital stage:
pleasure is gained through sexual intercourse with
non-relatives

25. Fixation. Freud believed that you can get stuck or fixated
at a stage if you were either under or over stimulated
during this stage. According to Freud, personality traits
are attached to these types of individuals.
A few examples:
Oral fixation: nail biters, gum chewers, smokers, etc.
Overly optimistic, dependent, and passive.
Anal retentive: Excessive need for order,
control and neatness. (modern day OCD)
Anal expulsive: emotionally volatile, unstable,
spiteful and vindictive

26. Defense Mechanisms:
1. Protect the ego from anxiety
due to the unconscious starting to
break through to the conscious
2. Deny or distort reality
3. Operate unconsciously
4. Cause people who are using
them to be absolutely convinced of
the correctness of their viewpoint.
5. can be healthy IF used in
moderation.
6. Were originally developed by
Anna Freud .

27. Defense Mechanisms.
Denial: blocking external events from awareness.
If a situation is too much to handle, the person refuses
to experience it. Examples: the failure to recognize the
death of a loved one, or students who fail to find out
their test grades!  [ you know who you are]
Repression: not being able to recall a threatening situation, person,
or event. Example: someone almost drowns as a child, but can't
remember the event even when people try to remind him -- but he
does have a fear of open water! [many fears and phobias]
Displacement: the redirection of an impulse onto a safer substitute
target. For example, someone who hates his or her mother may
repress that hatred and direct it instead towards women in general.
Projection: the tendency to see your own unacceptable desires in
other people. Examples: A faithful husband finds himself terribly
attracted to the lady next door. Rather than acknowledge his own
feelings, he becomes increasingly jealous of his wife, constantly
worried about her faithfulness.

28. Reaction formation: what Anna Freud called "believing the
opposite“. Changing an unacceptable impulse into its opposite.
Example: “I hate Mom” becomes “I really love Mom a lot!!!”. The
individual will often go above and beyond in their expression of love
in order to alleviate feelings of guilt and anxiety.
Regression: a movement back in psychological time when one is
faced with stress. When we are troubled or frightened, our behaviors
often become more childish or primitive. A child may begin to suck
their thumb again or wet the bed.
Rationalization: the cognitive distortion of "the facts" to make an
impulse more acceptable. We do it often enough on a fairly conscious
level when we provide ourselves with excuses. Many of us are quite
prepared to believe our lies.
Sublimation: the transforming of an unacceptable impulse, whether
it be sex, anger, or fear, into a socially acceptable and productive form.
So someone with a great deal of hostility may become a hunter, a
butcher, a football player, or a mercenary. For Freud, all positive
creative activities were sublimations mostly of the sex drive.

29. Limitations of Freud’s theory:
- Untestable: How can you objectively measure the
“unconscious”? Does not follow the scientific
method.
- Almost all of his case studies were upper-class
Austrian women: sample bias?
- Did not allow for prediction of future behaviors
- Placed too much emphasis on early childhood
experiences in shaping personality

30. When a student asked him what the significance of his
cigar was, Freud replied “sometimes a cigar is just a
cigar”.

31. Neo-Freudians: students of Freud who eventually started
their own school of thought due to major disagreements
with some of Freud’s ideas.
Carl Jung: 1875-1961. (pronounced – Young).
- Analytical psychology
- Born in Switzerland, trained as a psychiatrist
- Believed Freud placed too much emphasis on sexuality as a
motive for behavior

32. Famous quote:
“Anyone who wants to know the human psyche will learn
next to nothing from experimental psychology. He would
be better advised to abandon exact science, put away his
scholar's gown, bid farewell to his study, and wander with
human heart throughout the world. There in the horrors
of prisons, lunatic asylums and hospitals, in drab suburban
pubs, in brothels and gambling-hells, in the salons of the
elegant, the Stock Exchanges, socialist meetings, churches,
revivalist gatherings and ecstatic sects, through love and
hate, through the experience of passion in every form in
his own body, he would reap richer stores of knowledge
than text-books a foot thick could give him, and he will
know how to doctor the sick with a real knowledge of the
human soul”. -- Carl Jung

33. Jung’s Analytical Psychology broke the unconscious down further
into 2 parts:
a. Personal unconscious (similar to Freud’s id)
b. Collective unconscious ** (new concept)
collective unconscious: a kind of universal memory bank that
contains all the ancestral memories, images, symbols, and ideas
that humankind has accumulated throughout time
Jung used the term collective to stress that the content of this
part of the unconscious mind is the same for all humans – it is
genetic.
He placed particular emphasis on one key component of the
collective unconscious called archetypes, which consist of
powerful, emotionally charged, universal images or concepts
that are inherited or passed down from generation to generation

34. The four main Jungian archetypes are:
the self
the shadow or the dark side of the human psyche
the anima (the female counterpart to the male
psyche)
and the animus (the male counterpart to the female
psyche).

35. For example: According to Jung, we create war
and conflict in order to fulfill the needs of the
collective unconscious.
We need the hero! We need the villain!
According to Jung, these are all archetypes that
have been inherited from our ancestors
**Question: Does history repeats itself because of
the collective unconscious and the archetypes?

36. Alfred Adler: Individual psychology.
1870-1937 (Vienna, Austria): MD (opthamologist).
“Behind everyone who behaves as if he were superior to
others, we can suspect a feeling of inferiority which calls for
very special efforts of concealment. It is as if a man feared
that he was too small and walked on his toes to make
himself seem taller.“ - Alfred Adler
Adler coined the term “inferiority complex”

37. Adler came to believe in the importance of “feelings of
inferiority” in motivating human behavior
To be a human being," he wrote, "means to feel oneself
inferior." Adler believed that inferiority feelings are the source
of all human striving. All individual progress, growth and
development result from the attempt to compensate for one's
inferiorities.
Style of life = an individuals unique pattern of “striving for
superiority” to overcome feelings of inferiority
Inferiority complex - When an inability to overcome
inferiority feelings heightens and intensifies them.

38. Adler disagreed with Freud about:
- the emphasis on sexuality
- the importance of the unconscious
- “a stream of consciousness” – Adler believed that
all three parts of the psyche are constantly
interacting & do NOT act alone.
- While Adler believed our childhood experiences
were important, he also believed in what he called
“teleology” or being motivated towards future
goals.
- Alder felt Freud placed too much emphasis on the
past. Some consider Adler the forefather of
humanism.

39. Karen Horney. 1885 – 1952. nee Hamburg, Germany
Studied to be an MD. In 1909 she entered the University of
Freiburg .
Feminine psychology. Argued strongly against Freud’s
notion of both the Oedipus and Electra complex
Disagreed with Freud’s psychosexual stages
Did not accept Freud’s division of the psyche into the id,
ego, and superego
Countered Freud’s idea of “penis envy” with what she
called “womb envy”
Agreed with Freud on the importance of the unconscious
and early childhood
Believed that personality could continue to develop and
change throughout life

41. Humanistic psychology
 focused on uniquely human issues such as: the
self, health, hope, love, creativity, nature, and
individuality.
 Believed in innate goodness – born good
 Derived somewhat from existentialism: a strong
belief in free-will and conscious rational
decision-making
 Arose in reaction to behaviorism and
psychodynamic theory

42. Self concept or self image
Self as a object
Self as a process

43. Humanistic Approaches to
Personality
Humanistic psychology
An approach to personality that focuses on the
self, subjective experience, and the capacity
for fulfillment
Humanist psychologists:
1. Abraham Maslow
2. Carl Rogers
3. Rollo May

44. Maslow developed his famous “Hierarchy of Needs”
Differentiated between Deficiency needs and Growth needs:
Deficiency needs are the bottom four levels in the hierarchy:
these needs must be met or filled before other growth needs
can take over
Maslow believed deficiency needs must be met in order of the
hierarchy – e.g. – physiological 1st
, safety 2nd
, etc.

45. Growth needs or being needs – the highest motive in
the hierarchy for human behavior. This motive takes over
only when all other deficiency needs are met
Some growth needs that Maslow discussed are:
- Truth, rather than dishonesty
- Aliveness, not deadness or the mechanization of life
- Uniqueness, not bland uniformity
- Perfection and necessity, not sloppiness,
inconsistency, or accident.
- Justice and order, not injustice and lawlessness.
- Simplicity, not unnecessary complexity.
- Self-sufficiency, not dependency.

46. Abraham Maslow. (1908-1970). Born in Brooklyn,
New York. One of seven children of Russian
immigrants. Graduated University of Wisconsin with
PhD (worked with Harry Harlow)
Returned to NY to work with Edward Thorndike at
Columbia University

47. "A musician must make music, an artist must
paint, a poet must write, if he is to be at peace
with himself. What a man can be, he must be.
This is the need we may call self-actualization ...
It refers to man's desire for fulfillment, namely to
the tendency for him to become actually in what
he is potentially: to become everything that one
is capable of becoming ..." - Abraham Maslow

48. Maslow’s Characteristics of Self-Actualizers:
Reality focused and problem-centered
The journey is often more important than the ends.
They enjoy solitude, and are comfortable being alone.
Enjoy deeper personal relations with a few close
friends and family members
Value autonomy, a relative independence from
physical and social needs.
They have an unhostile sense of humor -- preferring
to joke at their own expense, or at the human condition,
and never directing their humor at others.
spontaneity and simplicity: They prefer being
themselves rather than being pretentious or artificial.

49. They have a sense of humility and respect towards others
They have a certain freshness of appreciation, an ability to
see things, even ordinary things, with wonder.
They are creative, inventive, and original.
tend to have more peak experiences than the average person.
[A peak experience is one that takes you out of yourself, that
makes you feel very tiny, or very large, to some extent one with
life or nature or God. It gives you a feeling of being a part of the
infinite and the eternal. These experiences tend to leave their
mark on a person, change them for the better, and many people
actively seek them out. They are also called mystical
experiences, and are an important part of many religious and
philosophical traditions].
Their values are "natural" and seem to flow effortlessly from
their personalities

50. Maslow identified the following historical figures as self-actualizers:
- Abraham Lincoln
- Thomas Jefferson
- Benjamin Franklin
- George Washington
- Albert Einstein
- Aldous Huxley
- William James
- Spinoza
- Goethe
- Pierre Renoir
- Robert Browning
- Walt Whitman
- Henry Wadsworth Longfellow
- Eleanor Roosevelt

51. The Humanistic Approach
Abraham Maslow
The State of Self-Actualization
Csikszentmihalyi
studied this, based on
Maslow’s writings.
A state of “flow”
arises when engaging
in activities
demanding skill and
challenge, but are not
too difficult.
Flow, The Optimal
Experience

52. Your turn
You are on your way to a restaurant to meet some
friends, and you are hungry. As you are walking
from your car to the restaurant, you are looking
forward to talking with your friends. Just then, you
hear a gunshot. According to Maslow, your primary
motivation would be determined by
1. Your hunger
2. Your desire to converse with your friends
3. Your desire for safety
chapter 2

53. Carl Rogers. 1902-1987
Carl Rogers was born January 8, 1902 in Oak Park,
Illinois, a suburb of Chicago, the fourth of six
children. His father was a successful civil
engineer and his mother was a housewife and
devout Christian.
In 1942, he wrote his first book, Counseling and
Psychotherapy.
1945, he was invited to set up a counseling center
at the University of Chicago. It was while working
there that in 1951 he published his major work,
Client-Centered Therapy, wherein he outlined his
basic theory.
Phenomenal field??

54. View of people as basically good
The “actualizing tendency” is the basic force of life –
we are always trying to better ourselves in some way
True self: who you are today
Ideal self: who you want to become
Self-actualization is the process of becoming your
ideal self

55. The Humanistic Approach
Carl Rogers
The Personality Theory of Carl Rogers

56. Humanistic Psychology:
Carl Rogers
Interested in fully functioning individuals
Congruence
this is displayed by fully functioning people and is a harmony
between the image they project to others and their true
feelings or wishes
To become fully functioning we need:
Unconditional positive regard
A situation in which the acceptance and love one receives
from significant others is unqualified, no strings attached
Unfortunately many children and adults are treated
with:
Conditional positive regard
A situation in which the acceptance and love one receives
from significant others is contingent upon one’s behavior
chapter 2

57. Unconditional positive regard: a feeling of
total love and acceptance – like that of a child for
a parent, or a pet to its owner. No matter what
you say or do, you will be loved and accepted.
Rogers believed if a child received unconditional
positive regard, he/she would be able to self-
actualize and become his/her ideal self
If self-actualization is blocked, mental illness
would ensue

58. Conditions of worth: if…then contingencies.
I will love and accept you if…;Rogers believed this is
another pathway to mental illness
The individual who is raised with “conditions of
worth” will not actualize into their ideal self.
The individual who is raised with conditions of worth
will actualize into another persons’ vision of their
ideal self.
How much of what you say and do is based on
conditions of worth?
What must parents do to avoid using “conditions of
worth” when raising their children? Society at large?

59. The Humanistic Approach
Carl Rogers
Self-Esteem
A positive or negative evaluation of the self
 Self-Schemas
Specific beliefs about the self that influence how
people interpret self-relevant information

60. The Humanistic Approach
Self-Esteem
Self-Discrepancy Theory
According to this theory, self-esteem is defined by the match
between how we see ourselves and how we want to see
ourselves.

61. Evaluating humanist
approaches
The bad:
1.Assumptions are not testable
2.Hard to operationally define many of the concepts
3.For taking people’s self-report statements at face value
4.For being too optimistic about human nature and ignoring human capacity for evil
The good:
1.Added balance to the study of personality
2.Encouraged others to focus on “positive psychology”
3.Fostered new appreciation for resilience
4.For the idea that the self-concept is the heart of personality

63. Cognitive Social-Learning Theory
An approach to personality that focuses on
social learning (modeling), acquired cognitive
factors (expectancies, values), and the person-
situation interaction

64. The Cognitive Social-Learning
Approach
Principles of Learning and Behavior
Classical Conditioning
Operant Conditioning
Stimulus Generalization
Discrimination
Extinction

65. The Cognitive Social-Learning
Approach
Social-Learning Theory
Modeling
The social-learning process by which behavior is
observed and imitated
Locus of Control
The expectancy that one’s reinforcements are generally
controlled by internal or external factors
Self-Efficacy
The belief that one is capable of performing the
behaviors required to produce a desired outcome

66. The Cognitive Social-Learning
Approach
Perspectives on Cognitive Social-Learning
Theory
Reciprocal Determinism
Personality emerges
from the mutual
interactions of
individuals, their
actions, and their
environments.

67. Early social learning theory:
Dollard and Miller in 1930s
Learning theory on basis of Freud psychoanalytical
theories.
Conflict between approach and avoidance tendencies
Skinner’s radical behaviorism

68. Social learning; later
 Albert Bandura (1925-present)
 Albert Bandura was born December 4, 1925, in the
small town of Mundare in northern Alberta,
Canada.
 In 1953, he started teaching at Stanford University.
While there, he collaborated with his first graduate
student, Richard Walters, resulting in their first
book, Adolescent Aggression, in 1959.
 Emphasis on the cognitive or thoughts [covert]

69. Modeling; Vicarious learning; Observational learning:
learning by watching others. Thoughts matter!!
Interested in studying the effect of television violence on
aggression in children. Bandura is most famous for his
Bo-Bo doll studies.
Film: woman punching the clown, shouting “sockeroo!” She kicked it,
sat on it, hit it with a little hammer, and so on, shouting various
aggressive phrases. Bandura showed his film to groups of
kindergartners who, as you might predict, liked it a lot.
what did the observers record afterward: A lot of little kids beating the
daylights out of the bobo doll. They punched it and shouted
“sockeroo,” kicked it, sat on it, hit it with the little hammers, and so on.
In other words, they imitated the young lady in the film, “and quite
precisely at that”.
Bryan and Test, Good Samaritanism experiment

70. Bandura added cognition or thought to the equation
The main “person” factor that Bandura discussed
was: self-efficacy: the belief in your ability to
perform a certain task or function.

72. Genetic Influences on Personality
Nature vs. Nurture debate
Nature: Biology/genetics determines personality
Nurture: Experiences determines personality
Not mutually exclusive
 Biology and experience interact and shape our personalities together
How can biology influence our personality?
Genes: functional units of heredity, composed of DNA and specify
the structure of proteins
 Specify how the brain and nervous systems should develop and
function
 Influence the behaviors that make up our personality

73. How do psychologists measure genetic
contributions to personality?
1. Studying personality traits in other species
2. Studying temperaments of infants and children
3. Heritability studies in twins and adopted
individuals

74. Personality Traits in Other Species
Examine the physiology, genetics, ecology and ethology of
animals
Evidence of 4 of the Big Five traits in 64 different species
 monkeys  dogs  octopi
 Conscientiousness has only been found in humans
Puppy Personality Experiment (Gosling, 2003)
 Owners provided personality assessments of dogs and themselves
 A person who knew them both filled out a personality inventory
 Independent observers rated the dogs in a park
 All 3 ratings were very similar

75. Personality Traits
in Infants and Children
Temperaments
Physiological dispositions to respond to the environment in certain ways
 Present in infancy, assumed to be innate
 Relatively stable over time
Temperaments:
1. Easy/Flexible: positive disposition, curious about new situations,
adaptable, low-moderate emotional intensity
40% of babies
1. Difficult/Feisty: negative moods, slow to adapt to new situations
10 % of babies
1. Slow-to-Warm: inactive, calm reactions to environment, negative
moods and withdraw from new situations, adapt slowly
15 % of babies
35 % have babies have combination of characteristics and can’t be
categorized
chapter 2

76. chapter 2
Dimension of Temperament Definition
1. Activity level Proportion of active to inactive time
2. Approach-Withdrawal The response to a new person or object,
based on whether the child accepts or
withdraws from the situation
3. Adaptability How easily the child is able to adapt to
changes in his or her environment
4. Quality of Mood The contrast of the amount of friendly, joyful, and
pleasant behavior with unpleasant, unfriendly
behavior
5. Attention span and persistence The amount of the time a child devotes to an activity and
the effect of distraction on that activity
6. Distractibility The degree to which stimuli in the
environment alters behavior
7. Rhythmicity (regularity) The regularity of basic functions, such as
hunger, excretion, sleep and wakefulness
8. Intensity of reaction The energy level or reaction of the child’s
response
9. Threshold of responsiveness The intensity of stimulation needed to elicit a
response

77. The Heritability of Personality
Traits
Heritability
a statistical estimate of how much variation in a trait
can be attributed to genetics within a given population
 0 – 1.0
 0.5 = 50 % of the variation in a personality trait can be attributed
to genetics
 1.0 = 100 % of the variation in a personality trait can be attributed
to genetics
Heritability of personality traits is about 0.5
Within a group of people, about 50% of the variation associated with a
given trait is attributable to genetic differences among individuals in
the group.
Genetic predisposition is not genetic inevitability
chapter 2

78. The Heritability of Personality
Traits
How is heritability studied?
 Adoption studies
 Compare correlations between traits of children and
their biological and adoptive parents
 Twin Studies
 Identical twins = share 100 % of genes
 Fraternal twins = share about ½ genes, just like
regular siblings
 Compare same-sex groups of identical and
fraternal twins
 Look at personality traits in adopted identical and
fraternal twins
chapter 2