Psychology Chapter 3 Objectives 1-16

Objective 5: Cite ways that behavior geneticists us adoption studies to understand the effects of environment and heredity.

Adopted children carry the genetic inheritance from their biological parents into an environment created by their adoptive families. Similarities between the child and the biological relatives give clues to the influence of heredity. Similarites between the child and the adoptive relatives give clues to the influence of environment. Adopted children tend to resemble their biological parents in their personality (their characteristic pattern of thinking, feeling, and acting), and their adoptive parents in their values, attitudes, manners, faith, and politics.

Objective 13: Describe evolutionary explanations for gender differences in sexuality.

Applying principles of natural selection, evolutionary psychologists interpret human sexual behavior in terms of its survival value- the tendency of behaviors to be selected if they increase the likelihood of sending one's genes into the future. Thus, being attracted to multiple healthy, fertile appearing partners increases men's chances of spreading their genes widely and reproducing. Because women incubate and nurse babies, they increase their own and their children's chances of survival by searching for mates with economic resources and social status, who have the potential for long-term mating and investment in their joint offspring.

Objective 2: Describe the types of questions that interest behavior geneticists.

Behavior geneticists are especially interested in the extent to which genetics and environment influence our behavior, creating individual differences. In this context, environment means every external, nongenetic aspect of our lives from prenatal nutrition to the people and things around us now.

Objective 16: Describe how experience can modify the brian.

During maturation, a child's neural connections increase in areas associated with repetitive activities (vision, for example). Unused synapses degenerate, as happens in the brain cells normally assigned to vision in the cortex of children with congenital and untreated cataracts. Though the process is most evident in the brains of young children, growth and prunin of synapses continue throughout life.

Objective 10: Describe the area of psychology that interests evolutionary psychologists.

Evolutionary psychologists attempt to understand how natural selection has shaped behaviors found throughout the human species.

Objective 12: Identify some gender differences in sexuality.

Gender refers to the biologically and socially influenced characteristics by which we define male and female. Men and women differ in their attitudes toward sex: Men are more approving of casual sex, think about sex more often, and are more likely to misinterpret friendliness as sexual interest. Women are more likely to cite affection as a reason for first intercourse and to have a relational view of sexual activity. Similar differences appear in sexual behavior. Men masturbate more often, initiate sexual activity more frequently, and make more sacrifices to gain sex.

Objective 7: Discuss heritability's application to individuals and groups, and explain what we mean when we say genes are self-regulating.

Heritability describes the extent to which variation among individuals can be attirbuted to genes. It applies only to differences among individuals- never to any one person. In an imaginary experiment that could create identical environments, any observed differences (weight) among people would be the result of their heredity, and hertiability would be 100 percent for that trait. Heretiable individual differences in traits such as height or intelligence need not explain group differences. Genes mostly explain why some are taller than others, but not why people today are taller than a century ago. Saying that genes are self-regulating means that genes are not blueprints; they can react differently in different environments.

Objective 4: Explain how identical and fraternal twins differ, and cite ways that behavior geneticists use twin studies to understand the effects of environment and heredity.

Identical twins develop from one egg that splits after being fertilized. They share the same set of genes, a similar prenatal environment, and-usually-the same family and culture after birth. Fraternal twins develop from seperate fertilized eggs and share a prenatal environment, family, and social-cultural environment after birth, so they are genetically no more similar than any other two sibilings. When some trait (such as extraversion) is present in both members of identical twins pairs but in only one member of fraternal twin pairs, researchers have a clue that heredity may be important in the development of that trait. Such comparisons are especially rich sources of information when twins have been seperated at (or shortly after) birth, letting researchers see more clearly the effects of heredity in different environments.

Objective 9: Identify the potential promise and perils of molecular genetics research.

Molecular geneticists study the molecular structure and function of genes in search of those that influence behaviors. Psychologists and molecular geneticists are cooperating in search to identify specific genes- or more often, teams of genes- that put people at risk for disorders. Knowledge of such links will enable medical personnel to inform expectant parents of some situations in which a fetus deviates from normal patterns. The ethical implications of such choices will be debated if parents choose to abort children who do not conform to their image of an ideal child.

Objective 14: Summarize the criticisms of evolutionary explanations of human behaviors, and describe the evolutionary psychologists' response to those criticisms.

One criticism is that evolutionary psychologists start with an effect and work backward to an explanation. Another is that the evolutionary perspective underestimates cultural expectations and socialization. A third is that the evolutionary viewpoint absolves people from taking ethical and moral repsonsibilities for their sexual behavior. Evolutionary psychologists respond that understanding our predispositions can help us overcome them. They also cite the value of testable predictions based on evolutionary principles, as well as the coherence and explanatory power of those principles.

Objective 15: Describe some of the conditions that can affect development before birth.

Prenatal environments differ in terms of nutrition and exposure to toxic agents. Even identical twins sharing a placenta can, because of their differing locations, have unequal access to nourishment and protection from viruses.

Objective 8: Give an example of a genetically influenced trait that can evoke responses in others, and give another example of an environment that can trigger gene activity.

Some human traits (such as having two eyes) develop in any environment, but many important psychological traits are a product of the interaction of our genetic predispositions and our surrounding environment. For example, a genetic predisposition that causes a child to be restless and hyperactive can evoke angry responses from parents or teachers. And a stressful environment can trigger genes that affect the production of neurotransmitters contributing to depression.

Objective 6: Discuss how the relative stability of our temperament illustrates the influence of heredity and environment.

Temperament, a person's characteristic level of emotional reactivity and intensity, is apparent soon after birth and tends to continue relatively unchanged into adulthood. This suggests that heredity plays a much larger role than environment in the development of temperament.

Objective 11: State the principle of natural selection, and point out some possible effects of natural selection in the development of human characteristics.

The principle of natural selection states that, among the range of possible variations in an inherited trait, the variations most likely to be passed on to future generations are those that increase the odds of reproducing and surviving. Genes that enabled a capacity to learn and to adapt had survival value for our ancestors, as did those that prepared people to survive in feast-or-famine conditions. We suffer the effects of famine less often, thanks to modern technology, but with a genetic legacy that causes us to store fat and decrease in rigorous exercise, we become obese. Charles Darwin, whose theory of evolution has for a long time been an organizing principle in biology, anticipated the contemporary application of evolutionary principles in psychology.

Objective 3: Define chromosome, DNA, gene, genome, and describe their relationships.

We have 46 chromosomes in each cell- 23 from our mother and 23 from our father. Chromosomes are threadlike structures made of DNA, a spiraling complex molecule containing genes. Our approximately 30,000 genes are DNA segments that, when "turned on" (expressed) form templates for the creation of various protein molecules, the building blocks of our physical and behavioral development. A genome is an organism's genetic profile- the complete set of instructions for making that organism, consisting of all the genetic material in its chromosomes. Combinations of variations at particular gene sites help define our differences. Most human traits are influenced by many genes acting together, not by the influence of a single gene acting alone.

Objective 1: Give examples of differences and similarities with the human family.

We humans differ from and resemble one another in many ways we differ in personality, interests, physical appearance, family background, culture, and native language. Our similarities include our biological heritage and needs, our shared brain architecture, our ability to use language, the senses with which we explore the world around us, and our social behaviors.