Tutorial 3 - Nature Vs. Nurture

Introduction to Psychology Tutorial 3 – Nature Vs. Nurture EVOLUTION AND EVOLUTIONARY PSYCHOLOGY A.

Theory of Evolution. 

Published “The Descent of Man” in 1871.

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Natural Selection: Survival of the fittest.

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Biology serves as the material base for our behaviors, emotions and cognitions.

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“Doing What Comes Naturally”. 

Mutations: differences in individual traits and/or adaptations for survival?

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Evolutionary Psychology: Applying adaptation and natural selection to mental processes and behavior.

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Instincts: stereotyped pattern of behavior that is triggered in specific situations o Examples of instincts: The Egg Zone; Stickleback Fish; Song of the Sparrow.

GENETIC INFLUENCE ON PERSONALITY HEREDITY: THE NATURE OF NATURE. A. Puppies and personality 1. Members of other species show reliably-discerned trait-like charateristics B. Heredity and temperament--temperaments are relatively stable, characteristic physiological dispositions that appear in infancy and have some genetic basis Heredity: one’s biological structures and processes transmitted from generation to generation. C.

Genetics and Behavioral Genetics. 

Behavioral Genetics: Bridges the sciences of psychology and biology. Concerned with the genetic transmission of traits that give rise to patterns of behaviors.

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Molecular Genetics: attempts to identify specific genes that are connected with behavior and mental processes.

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o Examples of this include: sociability, shyness, aggressiveness, thrill seeking, anxiety, depression, schizophrenia, bipolar disorder, alcoholism, and criminal behavior. D. GENES AND CHROMOSOMES: THE BUILDING BLOCKS OF HEREDITY”. 

Genes: basic building blocks of heredity. 30,000 - 40,000 genes within every cell of a person’s body.

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Chromosomes: strings of genes. Each cell contains 46 arranged in 23 pairs.

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DNA: Chromosomes are large complex molecules of deoxyribonucleic acid (DNA).

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Human Genome Project: has learned that the sequencing of your DNA consists of about 3 billion DNA sequences. o Genetic Code: The DNA sequences that “define” each person.

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Sperm and Egg: 23 chromosomes from the father’s sperm and 23 chromosomes from the mother’s egg. When the sperm fertilizes the egg they form 23 pairs.

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Sex Chromosomes: The 23rd pair of chromosomes, which determine a person’s sex, male or female. X female; Y male.

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Determined by father.

Down Syndrome. o Down Syndrome: an extra chromosome on the 21st pair. Usually contributed by mother. o Characteristics: downward sloping fold of skin at the inner corner of the eyes, a round face, a protruding tongue, broad flat nose, mental retardation, and physical problems that can result in death by middle age.

Other Genetic Disorders •

Albinism

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Breast Cancer

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Cleft palate

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Cystic fibrosis

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Down's Syndrome

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Hemophilia

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Huntington's disease

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Schizophrenia

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Sickle cell anemia

How heritable are personality traits? • Regardless of the trait, heritability is typically about .50 •

The only environmental effects on personality come from nonshared (with 2

family members) experiences--shared environment and parental child-rearing practices do not seem related to adult personality traits

Evaluating genetic theories • Not all traits are equally heritable or unaffected by shared environment •

Studies may underestimate the impact of environment

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Even traits that are highly heritable are not fixed

ENVIRONMENTAL INFLUENCES ON PERSONALITY A. Situations and social learning •

People don’t have “traits”--instead, they show patterns of behavior

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Reason for inconsistencies in behavior is that different behaviors are rewarded, punished, or ignored, depending on the situation

B. Social-cognitive learning theory •

Habits, beliefs, and behavior o a. Modern social-cognitive learning theories depart from classic behaviorism in their emphasis on three things: o Observational learning and the role of models o Cognitive processes, such as perception and interpretation of events o Motivating values, emotions, and beliefs, such as expectations of success or failure and confidence in ability to achieve goals 

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Habits and beliefs seen as exerting their own effects on behavior

Perceptions of control--much of human behavior is self-regulated, shaped by our thoughts, emotions, and goals o a. Reciprocal determinism is the interaction between aspects of the individual and aspects of the situation that shape personality 

Nonshared enviroment refers to the unique aspects of a person’s enviroment and experience that are not shared by family members

C. Parental influence and its limits •

Belief that personality is determined by how parents treat their children is challenged by three lines of empirical evidence:

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o The shared environment of the home has little, if any, influence on personality o b. Few parents have a single child-rearing style that is consistent over time and that they use with all of their children o c. Even when parents try to be consistent in the way they treat their children, there may be little relation between what they do and how the children turn out •

Peer environment consists of different peer groups, organized by interests,ethnicity, and/or popularity o Children and adolescents who are tempermentally fearful and shy are more likely to be bullied o Peers have a stronger influence on academic achievement than parents

Environmental Influences on the Brain Although the discussion in the text focuses on the physical structure of the brain, you might also want to remind students that brain function and structure are subject to environmental influences. Ask students to identify the behaviors that are important for keeping the brain healthy and functioning well. The following are some possibilities: Good nutrition, especially during childhood Adequate nutrition is vital for proper brain development. Even in adults, diet may influence brain function. Studies are showing that while high levels of cholesterol may be bad for your heart, low levels of cholesterol may be bad for the brain. Low cholesterol may be associated with low levels of the neurotransmitter serotonin, that can result in higher levels of aggression and depression. Mental stimulation High levels of stimulation help to form neural connections that in turn enhance brain function. Physical fitness Studies have shown that aerobic fitness has an impact on the density of capillaries in the brain. More capillaries result in greater blood flow to the brain. Maternal health during pregnancy The uterine environment can have an enormous impact on the brain development of a fetus. Women who do not have adequate nutrition, or drink, smoke, or do drugs, and who are exposed to certain environmental toxins are more likely to have children with lower IQs and learning disabilities.

CULTURAL INFLUENCES ON PERSONALITY A. Culture, values, and traits 4

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Two kinds of cultures o Individualist--individual needs take precedence over group needs o Collectivist--group harmony takes precedence over individual wishes

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Cultures’ norms and values vary o Conversational distance o Tardiness 

In monochronic cultures, people do one thing at a time; value promptness (e.g., northern Europe, Canada, United States)

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In polychronic cultures, people do several things at a time; promptness not valued (e.g., southern Europe, Middle East, South America, Africa) B. Culture and testosterone 

Higher rates of violence in southern United States

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Culture of honor in southern United States

C. Evaluating cultural approaches 

Cultural psychologists describe cultural influences on personality, avoiding stereotyping

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Regional variations occur in every society

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Many cultures share many human concerns (e.g., need for love, attachment, family, work, religion)

D.

KINSHIP STUDIES: IS THE BEHAVIOR OF RELATIVES RELATED? 

Parents and Children: 50% of their genes in common. Aunts and Uncles have a 25% overlap with nieces and nephews. 12.5% overlap with cousins.

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Kinship Studies: Studies which attempt to compare the presence of traits and behavior patterns in people who are biologically related or unrelated to help determine the role of genetic factors.

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Twin Studies: Looking Into the Genetic Mirror. o Monozygotic Twins (MZ): Identical twins from the same fertilized egg. o Dizygotic Twins (DZ): Fraternal twins, two separate fertilized eggs. o Twin studies compare the presence of traits in MZ twins, DZ twins and others to help determine the role of genetic factors.

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o If MZ twins show greater similarity on a trait than DZ twins a genetic basis for the trait has been suggested. 

The case of the Jims.... MZ twins raised apart, both named Jim, both were married and divorced, both trained to be policemen, first sons named James Allen, drove same kind of car, vacationed at the same beach, enjoyed carpentry as a hobby.

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Adoption Studies.

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Adoption studies: look for similarities between children and their natural and adoptive parents. o When children reared by adoptive parents are more similar to their natural parents in a particular trait, strong evidence exists for a genetic role.

E. SELECTIVE BREEDING: selective breeding to enhance desired physical and behavioral traits. 

Examples: cattle, chicken, dogs. o Tryon rat studies: Bred rats to become “maze dull” and “maze bright”. 

By the seventh generation maze bright rats are making only one error per trial, maze dull are making 9-10 errors per trial.

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