Nature and Nurture of Behavior

What are the issues in Development?

Nature/Nurture - what accounts for the changes? Are our inherited traits due to DNA in our genes or the experiences and interaction in our environment?

Continuity/Discontinuity - Is development gradual and continuous from start to finish, or is it discontinuous with abrupt changes like a caterpillar to a butterfly?

Stability/Change - Is our personality set at an early age or do we change at each stage of development or over the years?

  1. Genetics
    1. Genes: Our Biological Blueprint
    2. DNA (deoxyribonucleic acid)
      1. a complex molecule containing the genetic information that makes up the chromosomes
      2. has two strands-forming a "double helix"- held together by bonds between pairs of nucleotides
    3. Biochemical units of heredity that make up Chromosomes
      1. threadlike structures made of DNA molecules that contain the genes
      2. segment of DNA capable of synthesizing a protein
        1. Fraternal twin - two ovum, Identical Twins - one ovum
        2. Only identical twins have similar genetic content
        3. Inside sperm or ovum are 23 chromosomes, each with thousands of genes. The genes are composed of DNA.
        4. After fertilization there is a total of 23 pairs or 46 chromosomes in the developing zygote.
    4. Genotype (DNA) and Phenotype (Physical Appearance)
      1. Genome
        1. the complete instructions for making an organism
      2. Genes contain the instructions for various traits
        1. Phenotypes are the observable physical traits
        2. Genotypes are the genetic patterns carried within the cells
        3. Important because effect health of children (overhead of eye color), the parent may be carrier such as sickle cell anemia, or PKU (phenylketonuria which is genetic and can contribute to retardation. Put on diet low in phenylalanine.
    5. Prenatal Development
      1. Begins with fertilization - meeting of sperm & ovum, 2 weeks differentiate cells called an embryo.
      2. Three months called a fetus, as resembles a human infant
      3. Effects of Heredity and Environment
        1. Role of genetic inheritance on development of children's abilities is known but it does act alone.
        2. Originally psychologists thought it was a strong effect of achievement and others factors, today it is not believed as strongly, they feel a combination of heredity and environment
      4. Environmental factors
        1. Drugs such as ETOH and some viruses pass through placenta to fetus.
        2. Know as little as 3 drinks/day cause arousal and learning problems in children.
        3. Heavier drinking causes FAS Fetal Alcohol Syndrome, the 3 rd leading cause of mental retardation in US.
        4. Similar problems in offspring of mothers who smoke, low birth rate and related problems, and learning problems such as poor attention.
        5. Other factors include diseases from virus, infection in birth canal, teratogens or improper nutrition. All impact development in child.

  2. Gene Dominance
    1. When a person possesses differing genes for the same trait, one is often dominant over the other
    2. Eye color one example. If Mom is Bb and Dad is Bb, with the B(brown) dominant over the b(blue) there is only a 25% chance of having a blue eyed child. Blue only appears if genotype is bb. Any other combination results in brown eyes because of gene dominance.

  3. Evolutionary Psychology
    1. study of the evolution of behaviors using the principle of natural selection. Behaviors (from effect of the genes) that solved adaptive problems faced by our ancestors are passed on to the offspring (us).
      1. Natural Selection
        1. the principle that, among the range of inherited trait variations, those contributing to reproduction and survival will most likely be passed on to succeeding generations
      2. Mutation
        1. a random error in gene replication that leads to a change in the sequence of nucleotides
        2. the source of all genetic diversity or as in our discussions "the behavior"

  4. Behavior Genetics
    1. study of the power and limits of genetic and environmental influences on behavior
    2. Psychologists use Twin Studies
      1. Identical Twins
        1. develop from a single fertilized egg that splits in two, creating two genetically identical organisms
      2. Fraternal Twins
        1. develop from separate eggs
        2. genetically no closer than brothers and sisters, but they share a fetal environment

  5. Environment
    1. every nongenetic influence, experience, learning,

  6. Temperament
    1. a person's characteristic emotional reactivity and intensity

  7. Interaction
    1. the effect of one factor (such as environment) depends on another factor (such as heredity)

  8. Culture
    1. the enduring behaviors, ideas, attitudes, and traditions shared by a large group of people and transmitted from one generation to the next
    2. Norm
      1. an understood rule to accepted and expected behavior
      2. norms prescribe "proper" behavior
      3. usually not known to outsiders until violated

  9. Gender
    1. the characteristics, whether biologically or socially influenced, by which people define male and female
      1. X-Chromosome
        1. sex chromosome found in both men and women
        2. females have two, males have one
        3. an X-chromosome from each parent produces a female
      2. Y-Chromosome
        1. sex chromosome found only in males
        2. when paired with an X sex chromosome from the mother, it produces a male child

  10. Gender Role
    1. a set of expected behaviors for males and females

  11. Gender Identity
    1. one's sense of being male or female

  12. Gender-Typing
    1. the acquisition of a traditional masculine or feminine role

  13. Gender - Social Learning Theory
    1. we learn social behavior by observing and imitating (others who model the behavior - the social part) and by being rewarded or punished (the learning theory part)

  14. Gender - Schema Theory (schemas are ways we make sense of the world, our models)
    1. children learn from their cultures a concept of what it means to be male and female
    2. adjust behavior accordingly

  15. Methods used to study development
    1. Cross-Sectional Study - subjects studied are of different ages
    2. Longitudinal - Subjects studied as they age, sampled and tested at different points or ages

  16. Social Development
    1. Temperament
      1. Characteristic ways of responding to the environment that vary from infant to infant
      2. Originally classified by Thomas as Easy, Slow to Warm Up and Difficult. However, research was based on interview data
      3. Perceived to be biological in nature

  17. Parenting
    1. Over strict and controlling parents affect children, resulting in a withdrawn and distrustful child
    2. "Authoritative" parents give structure and guidance, self reliant and responsible
    3. Birth order - first higher IQ, later children social skill

Key Terms

Definitions for Nature vs Nature

Developmental Psychology Developmental psychology is the branch of psychology concerned with physical, cognitive, and social change throughout the life span.
Evolutionary Psychology study of the evolution of behaviors using the principle of natural selection
Behavior Genetics study of the power and limits of genetic and environmental influences on behavior
Culture the enduring behaviors, ideas, attitudes, and traditions shared by a large group of people and transmitted from one generation to the next
Gender the characteristics, whether biologically or socially influenced, by which people define male and female
Genes Biochemical units of heredity that make up Chromosomes
Chromosomes Chromosomes are threadlike structures made of DNA molecules that contain the genes. In conception, the 23 chromosomes in the egg are paired with the 23 chromosomes in the sperm.
Teratogens Teratogens (literally, poisons) are harmful agents, such as certain

drugs or viruses, that cross the mother's placenta and can harm the developing embryo or fetus.
Rooting Reflex The rooting reflex is the newborn's tendency, when his or her cheek is stroked, to move toward the stimulus and begin sucking.
Maturation Maturation refers to the biological growth processes that enable orderly changes in behavior and are relatively uninfluenced by experience Example: The ability to walk depends on a certain level of neural and muscular maturation. For this reason, until the toddler's body is physically ready to walk, practice "walking" has little effect.
Critical Period A critical period is an optimal period shortly after birth during which an organism must be exposed to certain experiences or influences if it is to develop properly.
Imprinting Imprinting is the process by which certain animals form attachments early in life, usually during a limited critical period.
Temperament Temperament refers to the rudiments of personality and a child's characteristic emotional reactivity and intensity. Temperament is a trait that is strongly linked to heredity.
Gender Gender is the social definition of male and female
Gender Identity Gender identity is one's sense of being male or female
Gender-typing Gender-typing is the acquisition of a masculine or feminine gender identity and role.
Social Learning Theory Social learning theory assumes that children learn gender-typed behaviors by observing and imitating and by being rewarded or punished.
Gender Schema Theory Gender schema theory assumes that gender becomes a cognitive "lens"through which children view their experience and acquire their gender identity.
Cross-sectional Study In a cross-sectional study, people of different ages are tested at

the same time.
Longitudinal Study In a longitudinal study, the same people are tested and retested over a period of years.
Social Clock The social clock refers to the culturally preferred timing of life events, such as leaving home, marrying, having children, and retiring.
Identical Twins Identical twins develop from a single fertilized egg that splits in two and therefore are genetically identical.
Fraternal Twins Fraternal twins develop from two separate eggs fertilized by different sperm and therefore are no more genetically similar than ordinary siblings.

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