Download PSYC 100 Chapter 4

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CHAPTER 4
Nature, Nurture, and Human Diversity
CHAPTER 4 OVERVIEW
 
Behavioral Genetics: Predicting
Individual Differences
 
Genes: Our Codes for Life
  Twin and Adoption Studies
  Temperament, Heredity, and
Personality
  Gene-Environment Interactions
Evolutionary Psychology:
Understanding Human Nature
Natural Selection and
Adaptation
  Evolutionary Success Helps
Explain Similarities
  An Evolutionary Explanation of
Human Sexuality
 
Gender Similarities and
Differences
  The Nature of Gender
  The Nurture of Gender
 
 
 
Parents and Peers
 
 
Parent and Early Experiences
Peer Influence
Gender Development
 
Reflections on Nature and
Nurture
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Variation Across Cultures
Variation Over Time
Culture and the Self
  Culture and Child-Rearing
  Developmental Similarities
Across Groups
 
 
 
 
 
Cultural Influences
INTRODUCTION
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Do certain universal behaviors occur across people?
Countries? Cultures?
What causes our striking diversity but also our
shared human nature?
  Environment: every nongenetic influence, from
prenatal nutrition to the people and things
around us.
  Behavior genetics is the study of the relative
power and limits of genetic and environmental
influences on behavior.
THE HUMAN BUILDING BLOCKS
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GENES: OUR CODES FOR LIFE
  Within
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the nucleus of a each cell lies the genetic
potential for an individual, in the form of 46
chromosomes
  These chromosomes are composed of DNA, a
double-helix strand that contains genes, which
code for specific proteins
  Genome: the complete instructions for making
an organism, all of the genetic material in that
organism’s chromosomes
TWIN AND ADOPTION STUDIES
 
Used to tease apart the influences of
environment and heredity:
 
 
 
Separated Twins
 
 
Jim Lewis and Jim Springer (page 137)
Biological versus Adoptive Relatives
 
 
Control home environment while varying
heredity (sibling studies)
Control heredity while varying home
environment (adoption studies)
Personality is far more similar to
biological parents than the caregivers
(adoptive parents)
Environmental effects are far
outweighed by heredity.
TEMPERAMENT AND HEREDITY
  Temperament:
a person’s characteristic emotional
reactivity and intensity.
 
 
 
differences that persist:
Emotionally reactive newborns tend to be the most
emotionally reactive 9-month-olds (Wilson & matheny,
1986; Worobey & Blajda, 1989)
Inhibited and fearful 2-year-olds are still relatively shy
at age 8; half will become introverted adolescents
(Kagan et al., 1992, 1994).
Emotionally intense preschoolers tend to become
intense young adults (Larsen & Diener, 1987).
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  Temperament
EVOLUTIONARY PSYCHOLOGY:
UNDERSTANDING HUMAN NATURE
1. 
2. 
3. 
4. 
 
Organisms’ varied offspring compete for survival
Certain biological and behavioral variations increase
their reproductive and survival chances in the
environment
Offspring that survive are more likely to pass their genes
to ensuing generations
Thus, over time, population characteristics may change
Fox Example
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Evolutional psychology is the study of the evolution
of behavior and the mind, using principles of natural
selection
  Natural selection: those traits that lead to
increased reproduction and survival will most likely
be passed on to succeeding generations
AN EVOLUTIONARY EXPLANATION OF
HUMAN SEXUALITY
  Having
 
 
Gender versus Sex
Behaviors related to reproduction (Schmitt, 2005,
2007).
Women: more relational
  Men: more recreational
 
  Nature
selects behaviors that increase the
likelihood of sending one’s genes to the future.
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faced the same challenges throughout our
history, men and women have adapted in similar
ways.
  Gender differences in Sexuality:
EVOLUTIONARY PSYCHOLOGY CONTINUED
  Drawbacks
 
 
It is difficult for evolutionary psychology to follow the
scientific method: starts with an effect and works
backward to propose an explanation.
Social consequences: suggestion of genetic
determinism, may rationalize unhealthy relationship
patterns.
Fails to consider the role of the environment.
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 
to this perspective:
RECAP
  Behavioral
genetics: relative power and limits of
environmental and genetic contributors.
 
 
Twin, adoption and family studies
Heredity outweighs environment
Temperament example
  Evolutionary
Psychology: study of the evolution
of behavior and the mind, using principles of
natural selection
 
 
 
Natural selection
Sexuality example
Drawbacks to this perspective
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 
PARENTS AND PEERS
  To
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Rats living in enriched environments have a heavier
cortex and more neuronal connections (more
dendrites) than their counterparts in “impoverished”
environments (Rosenzweig & Krech)
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what extent are our lives shaped by early
stimulation, by parents, and by peers?
  Evidence from animal research:
PARENTS AND PEERS
  Both
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nature and nurture sculpt synapses:
experience triggers pruning.
  Pruning follows a period during infancy of
exuberant brain growth characterized by
extensive addition of dendrites and synapses.
  Unused neural connections die off, leaving the
previously used connections more efficient.
  Simply stated: use it or lose it
PARENTS AND PEERS CONTINUED
 
Parents tend to choose the environment by selecting
the neighborhood and schools, the peers are part of
this environment.
  Peers
 
 
are one medium of cultural influence
Peers provide an additional avenue for learning –
they can model helpful or harmful behaviors
“Deviancy training”
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How much credit (or blame) do parents deserve?
  Parents/caregivers do play a role; specifics vary.
  What do parents choose for their children?
CULTURAL INFLUENCES
  What
 
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Culture is shared with the next generation.
Each generation chooses to keep or abandon certain
aspects of culture.
  Variations
 
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 
Across Cultures
Norm: an understood rule for accepted and expected
behavior. Norms prescribe “proper” behavior.
E.g. personal space, expressiveness, pace of life
Some aspects of culture vary widely even within the
U.S. E.g. pace of life
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is a culture?
  Culture: the enduring behaviors, ideas, attitudes,
values, and traditions shared by a group of people.
CULTURE AND THE SELF
  Cultures
 
Most common in North America, Western Europe,
Australia, or New Zealand
  Collectivism:
giving priority to goals of one’s
group and defining one’s identity accordingly
 
Group identifications provide belonging, values, a
network of caring individuals, security
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vary in the extent to which they give
priority to the nurturing and expression of
personal identity or group identity.
  Individualism: giving priority to one’s own
goals over group goals and defining one’s identify
in terms of personal attributes
VALUE CONTRASTS IN INDIVIDUALIST AND
COLLECTIVIST CULTURES
GENDER DEVELOPMENT
“Our biological sex in turn helps define our gender, the
biological and social characteristics by which people define
male or female,” (Myers, 2011, p. 126).
How do nature and nurture together form our gender?
 
23rd pair: Mother contributes X chromosome, Father
contributes X or Y chromosome
XX = female
  XY = male
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Nature of gender:
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4-5th month of prenatal development: Circulating sex
hormones
Potential for errors
Note gender differences in aggression, social power,
social connectedness as discussed in the chapter.
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 
  Biological
differences between
male and female brains
1. 
Cells: men have 4% more neurons,
100 grams more of brain tissue
2. 
Connections: women have more dendritic connections and
myelination
Corpus callosum: larger in women – greater access to both
sides of the brain in processing
3. 
4. 
Language: more lateralized (left) in men, language areas
larger in women
5. 
Inferior parietal lobule (IPL): larger in men, left side larger
in men while right side is larger in women
NURTURE OF GENDER
  Gender
role: a set of expected behaviors for
males or females
 
Can be specific to culture or family
Cultural attitudes toward gender roles vary over time
  Gender
identity: our sense of being male or
female
  Social learning theory: behavior is learned by
observing and imitating others
 
 
Parental modeling
Gender schemas
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 
REFLECTIONS ON NATURE AND NURTURE
NATURE AND NURTURE
  The
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nature versus nurture controversy is one of
the most heavily debated topics in the field of
Psychology
  Gene-environment interaction: “From conception
onward, we are the product of a cascade of
interactions between our genetic predispositions
and our surrounding environments” (Myers,
2010, p. 142).
CONCLUSIONS FROM CHAPTER 4
  Behavioral
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Genetics allows the understanding
and prediction of individual differences.
  Evolutionary Psychology, despite the drawbacks,
does help us comprehend evolution’s impact on
the mind.
  Parents, peers, and culture greatly influence
development.
  The similarities and differences of males and
females are strongly influenced by their genes
and their environment.
  Reflections on Nature and Nurture: Please read
this section carefully and consider your own
opinions on the topic of nature versus nurture.
CHAPTER 4 LEARNING OBJECTIVES
 
Behavioral genetics:
 
 
Evolutionary Psychology
 
 
 
 
Parents and Peers: Describe the role of early environment
in brain development.
Cultural Influences
 
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What is evolutionary psychology?
Describe natural selection.
Describe culture. What is a cultural norm?
Distinguish collectivist and individualist cultures.
Gender Development
 
 
Distinguish gender and sex.
Describe similarities and differences in males and females
(use evidence from the book). What are the roles of nature and
nurture in gender development?
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 
Describe behavioral genetics, DNA, chromosomes, and genes.
What is temperament? How is it influenced by genes and the
environment?