Introducing Psychology 4/17/2017 Psychology, 4/e by Saul Kassin Prepared by Michael J. Renner, Ph.D. These slides ©2001 Prentice Hall Psychology Publishing. CHAPTER 8: Nature and Nurture ©2001 Prentice Hall

Introducing Psychology Nature and Nurture 4/17/2017 Genes Evolution The Nature-Nurture Debates The Nature and Nurture Of... Prepared by Michael J. Renner, Ph.D. These slides ©2001 Prentice Hall Psychology Publishing. Psychology, 4/e by Saul Kassin ©2004 Prentice Hall ©2001 Prentice Hall

Genes What Genes Are and How They Work Introducing Psychology 4/17/2017 Genes What Genes Are and How They Work Genetics The branch of biology that deals with the mechanisms of heredity. Chromosomes Structures that contain DNA molecules in the form of genes. Deoxyribonucleic Acid (DNA) The structure of a chromosome that carries genetic information. Genes The biochemical units of heredity that govern the development of an individual life. Psychology, 4/e by Saul Kassin ©2004 Prentice Hall ©2001 Prentice Hall

Genes What Genes Are and How They Work Genetic Building Blocks Psychology, 4/e by Saul Kassin ©2004 Prentice Hall

Genes The Human Genome Project Introducing Psychology 4/17/2017 Genes The Human Genome Project Human Genome The genetic blueprint for making a complete human being The sequence of DNA is very similar in people all over the world Psychology, 4/e by Saul Kassin ©2004 Prentice Hall ©2001 Prentice Hall

Genes How Genes Affect Behavior Introducing Psychology 4/17/2017 Genes How Genes Affect Behavior Genotype The underlying DNA sequence that an individual inherits Phenotype An organism’s observable properties, physical and behavioral Genes contribute more directly to physical traits than to psychological characteristics. Psychology, 4/e by Saul Kassin ©2004 Prentice Hall ©2001 Prentice Hall

Evolution Natural Selection Introducing Psychology 4/17/2017 Evolution Natural Selection The evolutionary process by which some genes in a population spread more than others do, causing species to change over time. Principles of Natural Selection: Within a species, no two are alike. Individuals differ in their suitability to their environment. Those better suited are more likely to survive and reproduce. Reproduction perpetuates the genes of better suited individuals. Psychology, 4/e by Saul Kassin ©2004 Prentice Hall ©2001 Prentice Hall

Evolution Natural Selection Introducing Psychology 4/17/2017 Evolution Natural Selection Adaptations Advantageous physical and psychological traits that are inherited Mutations Random gene copying errors that can spark evolution by natural selection Psychology, 4/e by Saul Kassin ©2004 Prentice Hall ©2001 Prentice Hall

Evolution Natural Selection Natural Selection in the Galapagos Finches Introducing Psychology 4/17/2017 Evolution Natural Selection Natural Selection in the Galapagos Finches This is an example of evolution by natural selection. Due to the drought, an environmental change, a marked increase in the size of finches occurred. Larger birds survived and reproduced because their thicker beaks allowed them to open the seeds available to them. Psychology, 4/e by Saul Kassin ©2004 Prentice Hall ©2001 Prentice Hall

Evolution Evolutionary Psychology Introducing Psychology 4/17/2017 Evolution Evolutionary Psychology A subfield that uses the principles of evolution to understand human social behavior One example is explaining why people help others. Inclusive Fitness The notion that an organism’s genes are preserved not only through its own offspring but also through the offspring of genetic relatives. Kinship Selection Theory The tendency for organisms to help others according to their genetic relatedness. Reciprocal Altruism The tendency for organisms to help members of other species, who may later reciprocate. Psychology, 4/e by Saul Kassin ©2004 Prentice Hall ©2001 Prentice Hall

The Nature-Nurture Debates The Pursuit of Heritability Introducing Psychology 4/17/2017 The Nature-Nurture Debates The Pursuit of Heritability Nature-Nurture Debate The debate over the extent to which human behavior is determined by genetics and the environment. Heritability A statistical estimate of the percentage of the variability of a trait within a group that is attributable to genetic factors. Psychology, 4/e by Saul Kassin ©2004 Prentice Hall ©2001 Prentice Hall

The Nature-Nurture Debates The Pursuit of Heritability Introducing Psychology 4/17/2017 The Nature-Nurture Debates The Pursuit of Heritability Family Studies Studies that estimate genetic influences through similarities of family members who vary in their degree genetic relatedness Twin-Study Method A method of testing nature and nurture by comparing pairs of identical and fraternal twins of the same sex Adoption Studies A method of testing nature and nurture by comparing twins and other siblings reared together with those separated by adoption Psychology, 4/e by Saul Kassin ©2004 Prentice Hall ©2001 Prentice Hall

Psychology, 4/e by Saul Kassin ©2004 Prentice Hall The Nature-Nurture Debates The Pursuit of Heritability Measuring the Effects of Nature and Nurture Psychology, 4/e by Saul Kassin ©2004 Prentice Hall

The Nature-Nurture Debates Genetic Influences Introducing Psychology 4/17/2017 The Nature-Nurture Debates Genetic Influences Based on the Minnesota personality studies: When raised together, monozygotic twins are more similar than dizygotic twins. Twins raised apart are almost as similar to each other as those living in the same home. Psychology, 4/e by Saul Kassin ©2004 Prentice Hall ©2001 Prentice Hall

The Nature-Nurture Debates Genetic Influences Introducing Psychology 4/17/2017 The Nature-Nurture Debates Genetic Influences Other studies of twins and adoptees show: Genetic factors account for some differences in intelligence, verbal and spatial abilities, criminality, vocational interests, and aggressiveness. There is a genetic component to psychological disorders, such as alcoholism, depression, and schizophrenia. And, there is evidence for a genetic link to people’s attitudes toward issues and activities. Psychology, 4/e by Saul Kassin ©2004 Prentice Hall ©2001 Prentice Hall

Psychology, 4/e by Saul Kassin ©2004 Prentice Hall The Nature-Nurture Debates Genetic Influences Heritability of Various Human Attributes The role of genetic factors is shown by the extent to which identical twins are more similar to each other than are fraternal twin pairs. A correlation closer to one indicates greater similarity. Psychology, 4/e by Saul Kassin ©2004 Prentice Hall

Psychology, 4/e by Saul Kassin ©2004 Prentice Hall The Nature-Nurture Debates Genetic Influences Heritability of Attitudes This study involved 672 twins who rated their attitudes on various issues and activities. The results show some influence of genetic factors. Psychology, 4/e by Saul Kassin ©2004 Prentice Hall

The Nature-Nurture Debates Environmental Influences Introducing Psychology The Nature-Nurture Debates Environmental Influences 4/17/2017 The studies of twins and adoptees also support the importance of environmental influences. Genetic differences typically account for less than 50 percent of the variation in personality. Environmental factors account for the rest of the variation. Nonshared environments play a vital role in a person’s development and may be equally, or more, significant compared to shared environments. Psychology, 4/e by Saul Kassin ©2004 Prentice Hall ©2001 Prentice Hall

The Nature-Nurture Debates Environmental Influences A study of 5,542 three-year-olds found that Children with older brothers had higher masculinity scores Children with older sisters had higher femininity scores These results support the nurture hypothesis. Psychology, 4/e by Saul Kassin ©2004 Prentice Hall

The Nature-Nurture Debates The Interplay of Nature and Nurture Introducing Psychology 4/17/2017 The Nature-Nurture Debates The Interplay of Nature and Nurture Genetic and environmental influences are not independent. Identical twins receive more similar treatment from their parents compared to fraternal twins. People’s genetic makeup influences how they are treated by others, the environments in which they live, and the way they perceive and recall the details of that environment. Psychology, 4/e by Saul Kassin ©2004 Prentice Hall ©2001 Prentice Hall

The Nature and Nurture Of... Gender: A Great Divide? Introducing Psychology 4/17/2017 The Nature and Nurture Of... Gender: A Great Divide? Gender differences have been found in the following biological areas. Age when puberty is reached, height, weight, fat content, and amount each sweats Also, women are expected to live longer than men are. Psychology, 4/e by Saul Kassin ©2004 Prentice Hall ©2001 Prentice Hall

Gender: A Great Divide? How Are Men and Women Different? Introducing Psychology 4/17/2017 Gender: A Great Divide? How Are Men and Women Different? In the area of sexuality, men and women report different attitudes and behaviors, with men, in general, expressing more interest in sex. In the area of physical aggression, men generally are more physically aggressive compared to women. In the area of cognitive abilities, males tend to do better on tests of math and spatial abilities and females typically score higher on tests of verbal skills. Psychology, 4/e by Saul Kassin ©2004 Prentice Hall ©2001 Prentice Hall

Introducing Psychology 4/17/2017 Gender: A Great Divide? Why Do These Differences Between Men and Women Exist? Biological Perspectives These perspectives focus on the different levels of sex hormones, estrogen and testosterone, which have their greatest impacts during prenatal development and puberty. Psychology, 4/e by Saul Kassin ©2004 Prentice Hall ©2001 Prentice Hall

Introducing Psychology 4/17/2017 Gender: A Great Divide? Why Do These Differences Between Men and Women Exist? Environmental Perspectives Males and females have different life experiences because of how others treat them, that is, how they are socialized. Gender Roles Sex-typed behaviors promoted by social learning. Gender Schemas Beliefs about men and women that influence the way people perceive themselves and others. Psychology, 4/e by Saul Kassin ©2004 Prentice Hall ©2001 Prentice Hall

Introducing Psychology 4/17/2017 Gender: A Great Divide? Why Do These Differences Between Men and Women Exist? A Biosocial Theory Sex differences develop from an interaction between nature (biology) and nurture (environment). For example, although biological predispositions lead to a division of labor, today culture has a strong effect on the work roles of men and women. Psychology, 4/e by Saul Kassin ©2004 Prentice Hall ©2001 Prentice Hall

Gender: A Great Divide? Putting Sex Differences in Perspective Introducing Psychology 4/17/2017 Gender: A Great Divide? Putting Sex Differences in Perspective Men and women are similar in many, many ways. Differences are considered more newsworthy. Therefore, the similarities among males and females often are ignored. Psychology, 4/e by Saul Kassin ©2004 Prentice Hall ©2001 Prentice Hall

The Nature and Nurture Of... Sexual Orientation Introducing Psychology 4/17/2017 The Nature and Nurture Of... Sexual Orientation Origins of Homosexuality Both biological and environmental theories are offered to explain the origins of sexual orientation. Twin studies support the theory that sexual orientation has biological roots. A survey of gay men and their twins and adopted brothers found that 52 percent of the identical twins were gay, while only 22 percent of fraternal twins and 11 percent of adoptive brothers were gay. Psychology, 4/e by Saul Kassin ©2004 Prentice Hall ©2001 Prentice Hall

Psychology, 4/e by Saul Kassin ©2004 Prentice Hall The Nature and Nurture Of... Sexual Orientation Bem’s Developmental Theory Other theorists view sexual orientation as developing from both nature and nurture. Bem’s developmental theory of homosexuality states that genes determine childhood behaviors that later affect adolescents’ attraction to either the same sex or the other sex. Psychology, 4/e by Saul Kassin ©2004 Prentice Hall

Introducing Psychology 4/17/2017 ©2001 Prentice Hall