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Human Behavior


Human Behavior Nature, Nurture and Human Diversity – PowerPoint PPT presentation

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Title: Human Behavior

Human Behavior
  • Nature, Nurture and Human Diversity

Our behavior is often characterized as human
  • What do we mean by human nature?
  • How might a psychologist go about identifying the
    traits of human nature?

In a culture that emphasizes our differences, we
sometimes forget just how similar we are
Brainstorm and list all the universal behaviors
(behaviors shared among all cultures) that you
can think of
  • communicate both verbally and nonverbally
  • Enforce rules of etiquette
  • Avoid incest
  • Fear snakes / heights
  • Exchange gifts
  • Modesty in sexual behavior and bodily functions
  • Labor divided by age and sex
  • Men- more aggressive than women
  • Women provide more child care
  • Tools for work
  • Belief systems- death, disease
  • Plan for the future
  • Taboos- crimes and legal punishments
  • Marriage
  • Laugh / smile / mimic / joke / flirt / sympathize
    / tease / dance /
  • Music /Myths / folklore / poetry
  • Games
  • War

In a world of such diverse cultures, why do so
many universal behaviors exist?
  • Genetic similarities / shared DNA

Just how similar are we?
  • (True or False)
  • Fraternal twins are no more genetically similar
    than normal siblings.
  • If after a worldwide catastrophe only Icelanders
    or Kenyans survived, the human species would
    suffer a huge reduction in its genetic diversity.
  • We share 99.9 of our DNA with our neighbor!
    (Near clones!)
  • We are the leaves of one tree.

Nature, Nurture and Human Diversity
  • Essential Question What ultimately shapes our
  • Topics of Study
  • The Influence of genes Behavioral Genetics
  • Evolutionary Psychology and Natural Selection
  • Nurture and Early Development

Nature v. Nurture
  • Recognizing the difference
  • Sugar and spice and everything nice, thats what
    little girls are made of
  • Handsome is as handsome does.
  • Like father like son.
  • You cant teach an old dog new tricks.
  • Boys will be boys.
  • You are what you eat.
  • Blood will tell.
  • All men are created equal.

Genetics and BehaviorGetting started..
  • We know that both nature and nurture weave
    together to shape our behavior.
  • Its easy to prove that nurture influences
    behavior, but how could we devise a way to prove
    that genetics influences our behavior?

  • Read carefully pages 95-102
  • 1. Identify the following and explain how they
    collectively influence behavior.
  • chromosomes, DNA, genes, gene complexes
  • Explain specifically how studies contrasting
    fraternal and identical twins have helped prove
    that genetics influence individual behavior.
  • The case studies of Jim Lewis / Springer and
    Oscar Sohr / Jack Yufe (identical and separated
    at birth) provide evidence that genetics
    influences behavior. Explain specifically the
    strengths and weaknesses of these studies.

Behavior Genetics(Text Question 1)
  • Study individual behavioral differences. (weigh
    effects of nature, nurture)
  • Chromosomes 23 / egg, 23 / sperm (threadlike
  • Composed of DNA (deoxyribonucleic acid)
  • Genes 30,000 each / self-replicating units,
    synthesize proteins, (the building blocks of
    physical development
  • Gene complexes many genes acting in concert
  • Genes Influence physical make-up, intelligence,
    aggressiveness, happiness etc.

Behavior Genetics
Fraternal, Identical TwinsWhats the difference?
  • Fraternal (dizygotic)
  • Separate fertilized eggs (50 shared genes- no
    more genetic similarity than normal siblings)
  • Identical (Monozygotic)
  • Single fertilized egg split in two clones
  • (100 shared genes)

Fraternal vs. Identical
Fraternal v. Identical
Fraternal vs. Identical (2)
  • Fraternal / Identical twin study findings-
    provide specifics for the following
  • Alzheimers
  • Identical 60 / Fraternal30
  • Extraversion / neuroticism
  • Identical more similar than fraternal
  • Divorce rates
  • Identical x5.5 vs. fraternal x1.6
  • Schizophrenia
  • 50, 10, 3, 1 (identical, fraternal, sibling,
  • What are the limitations of these studies?
  • Genetics or environment? How do we

Twin StudiesJim Lewis / Springer
  • What does the study suggest? (3)

Jim an Jim
  • 37 days after birth
  • Romantic- love notes to wife
  • Son James, dog Toy, wife Linda
  • Woodworking (same bench in front yard)
  • Chevy, stock car racing, Miller Lite
  • Vasectomy, high blood pressure, chain smoker
  • migraines

The Bouchard Minnesota Twin Study
  • Are You a Natural- (handout questions)

Gerald Levy and Mark NewmanSeparated at Birth
Levy and Newman
  • Bouchards Minnesota Twin Study
  • Reunited by shared acquaintance
  • Upon meeting for first time
  • Same mustache, sideburns, glasses
  • Levey college degree in forestry- Newman planned
    to but worked for city trimming trees
  • Levey worked installing sprinker systems, Newman
    installed fire alarms
  • Both were bachelors, same taste in women
  • Both only drank Budweiser (pinky wrapped
    underneath can, crushed can afterwards)
  • Hunting, fishing, beach, John Wayne movies,
    pro-wrestling, Chinese food in wee hours
  • Volunteer firefighters
  • Both raised Jewish, neither particularly
  • When met- same remarks, at same time, same
    gestures- spooky
  • He is he and I am I, and we are one

Genetics and Behavior
  • Why has genetics not been given more
    consideration as a determiner of personality and
  • 2nd ½ of 20th century behaviorisms dominance
  • Experience as primary architect of human
  • Invisible genetics- cant see, touch or
    remember the influence
  • Determinism- compromises free will
  • Nurture gives parents measure of confidence- can
    control outcome
  • Bad, ineffective behavior can be unlearned
  • Why bother? Genetic argument reduces free will,
    cornered by determinism
  • That boy was born to act that way!
  • Reality Both play critical role in who you are!

Adoption Studies (5)
What insight has adoption studies provided
regarding the influence of genetics on
personality? (5)
  • Environmental relatives / biological Relatives
  • Finding subjects personality reflected
    biological relatives, even when adopted at birth
  • Conclusion people who grow up together dont
    resemble each other in personality
  • Why are two people raised together so
  • Confirmation of genes impact on personality

Environmental Influence
  • So what traits does nurture influence?
  • Values
  • Manners
  • Faith / religion
  • Politics
  • Social views

Heritability (6)
  • Extent to which difference between individuals
    can be attributed to genes
  • As environments become more similar, heredity as
    a source of difference becomes more important
    (and vice versa)
  • Heritable differences dont often translate to
    group differences

Temperament (7)
  • Our emotional excitability
  • Temperament traits tend to remain consistent
    through life
  • Studies confirm
  • Genetic temperament helps form enduring
  • Think of two examples of those you know.

Nature and Nurture
  • Genes are self-regulating (respond and adapt to
  • Individual differences almost always the result
    of both nature and nurture
  • Gene and scene dance together
  • Or, nurture works on what nature endows

Molecular Genetics (8)
  • Identify specific genes influence on behavior
  • Weight, extraversion, sexual orientation
  • LD, depression, schizophrenia, alcoholism
  • Designer babies?!?!

Human Nature?
  1. Why do infants start to fear strangers about the
    time they become mobile?
  2. Why are most parents so passionately devoted to
    their children?
  3. Why do so many more people have phobias about
    spiders and snakes than guns and electricity?
  4. Why are men quicker to perceive friendliness as
    sexual interest?

Evolutionary Psychology
  • Premise
  • (Darwins ) natural selection shapes our
    behavior, thinking (over time)
  • Certain traits, behaviors that enhance survival
    are passed on over generations

Dmitry Belyaev Domestication of Foxes
Belyaevs Experiment
  • 30 males, 100 females
  • Tamest 5 M, 20 F
  • 30 generations
  • Complete domestication
  • Now sold as house pets
  • Implications?
  • When certain traits are selected that give a
    reproductive advantage, those traits will prevail

Evolutionary Psychology
  • For the most part, evolutionary psychology helps
    to explain our similarities. (Universal
  • But it also helps explain some key differences.

Gender and Sexuality
  • On the issue of sex, would you characterize the
    attitudes and behaviors of men and women to be
    generally the same, or different? Explain and
    provide examples.

Gender and Sexual Attitudes / Behavior
  • Studies
  • 1978, FSU- research assistants / proposals for
    casual sex with strangers
  • 75 of men- yes 0 of women- yes
  • Questionnaire casual sex with different partners
  • 48 of men- yes 12 of women- yes
  • How can we explain this radical difference in
    sexual attitudes between the genders?

Gender Differences and SexualityNatural
selection would suggest that each gender pursued
attitudes and behaviors that perpetuated their
survival, and thus became part of our DNA over
  • Women- relational
  • Incubates, nurses one infant
  • Wants protection, assistance to ensure childs
  • Chooses wisely
  • Men- recreational
  • Perpetuate his genes (spread his genes through
    other females)
  • Chooses widely

Gender and AttractionStudy spanned 37 cultures
  • Men (attracted to)
  • Youthful, healthy, fertile
  • Waists 1/3 size of hips
  • Many children- genes to future
  • Women (attracted to..)
  • Mature, dominant, bold, affluent
  • Support and protect
  • Long- term mating, investment in joint-offspring

Gender Differences and Sexuality
  • Significance?
  • Nature selects behaviors that increase the
    likelihood of sending ones genes into the

In Conclusion
  • 4 important gender differences in human sexuality
    (Comprehensive Study Letitia Anne Peplau)
  • 1. Men show greater sexual desire than women
  • 2. Women tend to emphasize committed
    relationships as a context for sexuality (more
    so than men)
  • 3. Aggression is more closely linked to sexuality
    for men than women (powerful, domineering,
    experienced, individualistic)
  • 4. Womens sexuality shows greater plasticity
    (attitudes, behaviors about sex more easily
    shaped by cultural, social factors)
  • Example college (liberalizes womens attitude
    towards sex more than mens)
  • Chance of men identifying as gay or bisexual x2
  • Chance of women identifying as lesbian or
    bisexual x900!

Evolutionary Psychology
  • From an evolutionary psychology perspective, how
    might we explain marriage?

Nature, Nurture and Gender
  • Gender Development
  • Male, Female- What determines the gender?
  • 23rd pair of chromosomes determine sex
  • FemaleX, Male X or Y

Glad to be your gender?
  • Men
  • X4 to commit suicide, alcoholism
  • Autism, color blindness, hyperactivity,
    antisocial personality disorder
  • Women
  • 70 more fat
  • 40 less muscle
  • 5 inches shorter
  • Puberty 2 years earlier
  • Live 5 years longer
  • X2 for depression, anxiety
  • X10 for eating disorders

Gender and Aggression
  • Males tend to be more physically aggressive
  • Male-female arrest rate for murder
  • U.S. 9-1
  • Canada 7-1

Gender and Social Power
  • Universal pattern Men are more socially dominant
  • Men as leaders- more direct, autocratic, express
  • Women as leaders- more open, democratic, offer

Gender and Social Behavior
  • Males
  • Individualists
  • Boys larger play groups (activity focus)
  • Male Answer Syndrome
  • Freedom, self-reliance
  • Females
  • Interdependent (relationships)
  • Girls smaller groups (often one friend) less
    competitive, imitate social relationships
  • 85 of greeting cards!
  • More religiously oriented

Boys, girls and toysNature or Nurture?
  • Why do genders choose what they do?

Nature and Gender
  • Prenatal Months
  • 7th week develop male, female anatomical
  • 4th, 5th month Ovarian hormones, testosterone
    influence different brain development
  • Studies
  • Hines and Alexander Texas AM- Velvet monkeys
  • 1 day old infants video friendly face or
    mechanical mobile
  • 1 yr. old infants films faces or cars
  • Evidence suggests cognitive differences upon birth

Gender Differences and the Brain
  • New evidence structural, chemical and functional
    differences between genders and brains
  • Females thicker frontal lobe (verbal fluency)
  • Males thicker parietal Cortex (space perception)
  • Potential need for sex-specific treatments for
    addictions, depression, schizophrenia etc.

Nurture and Gender
  • Nurture influences our sense of gender by
  • Gender identity (cultures sense of being male or
  • Gender-typing casting, assigning traditional
    gender roles
  • Gender-Schema theory mental associations we make
    influence how we perceive gender in other issues
  • Social learning theory (Observation, imitation)

Genes rule??
  • In terms of personality, environmental factors
    typically account for less than 10 of childrens
    differences. (Key is how parents and peers
    influence those traits.)

Parenting the Genetic Code
  • Explain how one might address the following
    genetic traits for productive outcomes
  • sluggish, unresponsive, temperament as 3 month
  • Imaginative, slightly hyperactive, ADD high
    school student

What / Who has shaped you?
  • List the eight behavioral traits that most
    reflect your personality. For each, indicate
    which of the following has been most influential
    in shaping that trait.
  • Parents
  • Peers
  • Genes
  • Results? Which factor do you think most

Prenatal Environment
  • Studies indicate that identical twins who share
    the same placenta are more similar in
    psychological traits than those twins that dont.

Nurture and Early Neural Development
  • Early experience matters!
  • Fosters neural connections
  • Experience preserves activated neural connections
  • Unused ones degenerate (pruning)
  • Excess connectors in youth make kids more
    capable of mastering certain tasks.
  • Example?
  • Foreign language, (Accent and grammar) visual
    perception, musical instruments

Rat Studies
  • Rosenzweig and Krech
  • Isolated, impoverished vs. social, enriched
  • Young rats
  • Findings
  • Obvious differences in behavioral activity and
  • Heavier, thicker brain cortex (brain weight
    increased 7-10 percent and of synapses
    increased 20!)

Premature Babies
  • Neonatal units
  • Massage therapy stimulates growth
  • Speeds departure from hospital

Parents Influence
  • Genes determine human traits (personality)
  • Parents influence helps determine how those
    traits are expressed!
  • Genome gives the basic plot, the parent gives it
    its tone, accent and emphasis.
  • IOW- It starts with the kid, and the parents
    pick up on it.
  • Implications are huge for parenting (shaping
    genetic traits to be productive ones)

Peer Influence
  • True or False
  • Preschoolers who disdain a certain food despite
    parents efforts will often eat the food at a
    table of peers who like it.
  • A child who hears English spoken with one accent
    at home and another in the neighborhood and at
    school will invariably adopt the accent of his
    peers and not his parents.

Parents vs. Peers
  • Parents
  • Education
  • Discipline
  • Responsibility
  • Orderliness
  • Charitableness
  • Dealing with authority
  • Peers
  • Cooperation
  • Popularity
  • Styles of interaction

Nurtures SwayCultural Influences
  • Individualism
  • Self Independent
  • Life Task Discover, express ones uniqueness
  • What matters Me, personal achievement, rights,
    freedoms, self-esteem
  • Coping method change reality
  • Relationships Many, often temporary,
    confrontation acceptable
  • Behavior Reflects ones personality, attitude
  • Collectivism
  • Self Interdependent
  • Life Task fit in, perform role, obligations
  • What matters Us, group goals, family duty,
    social responsibility
  • Coping method Accommodate to reality
  • Relationships Few, close and long term, harmony
  • Behavior social norms and roles

Cultural Influences
  • Individualism
  • Collectivism
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