Chapter 4

Nature/NurtureEvolutionBehavior-Genetics

The Nature of Behavior and Mental ProcessesChromosomesHormonesBrain Structures/Chemicals

Genes: Our Biological Blueprint

Chromosomes 23 Pair Contain genetic material

DNA (deoxyribonucleic acid) Building blocks of the chromosomes has two strands-forming a “double helix”

Genes segment of DNA capable of synthesizing a

protein

Gender and Nature 23rd Chromosome = Sex

X from egg X or Y from spermXX = FemaleXY = Male

Testosterone (androgen) Levels/Testes Estrogen Levels/Ovaries Brain Development Identity

Cognitive Differences No differences for most cognitive abilities Verbal, reading, and writing— females

consistently score higher Spatial skills —males outscore females on

mentally rotating objects, females score better on remembering locations of objects

Math Skills— males score slightly better than females

The Role of HormonesHormones are chemicals that control bodily responses such as emotions, growth, and sexuality.

Males have more androgen.

Females have more estrogen.

Hormones play a lesser role in human development and behavior than they do in animals.

The sex hormones are estrogen and androgen.

The Nurture of Behavior and Mental Processes

Social Learning TheoryParentingPeersCultureNorms

The Nurture of Gender Gender Role

a set of expected behaviors for males and females

Gender Identity one’s sense of being male or female

Gender-typing the acquisition of a traditional masculine or

feminine role

Gender Role Stereotypes

The beliefs and expectations people hold about the typical characteristics, preferences, and behaviors of men and women

“I’m Glad I’m a Boy, I’m Glad I’m a Girl”

Gender Role Development Between ages 2-3 years, children can identify

themselves and other children as boys or girls. The concept of gender or sex, however is

based more on outward characteristics such as clothing.

Toddler girls tend to play more with dolls and ask for help more than boys

Toddler boys tend to play more with trucks and wagons, and tend to play more actively

After age 3 years we see consistent gender differences in preferred toys and activities

The Nurture of Gender Social Learning Theory

theory that we learn social behavior by observing and imitating and by being rewarded or punished

Gender Schema Theory theory that children learn from their cultures

a concept of what it means to be male and female and that they adjust their behavior accordingly

The Nurture of Gender

Two theories of gender typing

David(Brenda) Reimer

What, if any, aspects of David’s development support the nature theory of gender?

What aspects support the nurture theory?

Personality Differences

No significant differences between men and women on most characteristics

Women tend to be more nurturant than men (very broad)

Men tend to be more assertive than women (very broad)

Male/Female DifferencesThe only activity that is clearly defined along gender lines is reproduction. All other activities are shared by both sexes to different degrees.

Nurturance: Women generally show more empathy, but males can also be nurturing. No one has proven the existence of strong maternal instinct in humans.

Physical activity: Boys start out more physically active. By adulthood, differences in activity levels between genders have disappeared.

Aggression: Males are aggressive in more situations than females. Females do show aggression in some situations, however.

Mathematical AbilityStudies are not clear and have not as yet conclusively shown that males are innately better at math.

Males do better than females on the SAT math section, but study findings have not been consistent.

Teachers and parents have higher expectations for males.

Females may avoid difficult areas such as math.

Verbal Ability Includes not just speaking but also word problems, reading and writing. Generally, girls do better than males until early adolescence.

Evolutionary Psychology

Evolutionary Psychology the study of the evolution of behavior

and the mind, using the principles of natural selection

Gender in psychology, the characteristics,

whether biologically or socially influenced, by which people define male and female

Evolutionary Psychology

Natural Selection Mutations

random errors in gene replication that lead to a change in the sequence of nucleotides

the source of all genetic diversity Maximizing Fitness

Maximizing the fitness of your gene pool by selecting a mate with healthy genes and thus increasing your chances of producing healthy offspring.

Evolutionary Psychology

Critiquing the Evolutionary Explanation

Evolutionary psychologists make too many hindsight explanations.

Behavior Genetics

Behavior Genetics study of the relative power and limits of

genetic and environmental influences on behavior

Environment every nongenetic influence, from

prenatal nutrition to the people and things around us

Behavior Genetics Identical (monozygotic)

Twins develop from a single

fertilized egg that splits in two, creating two genetically identical organisms

Fraternal (dizygotic) Twins develop from separate eggs genetically no closer than

brothers and sisters, but they share the fetal environment

Identicaltwins

Fraternaltwins

Samesex only

Same oropposite sex

Behavior Genetics Temperament

a person’s characteristic emotional reactivity and intensity

Heritability the proportion of variation among

individuals that we can attribute to genes may vary, depending on the range of

populations and environments studied

Behavior Genetics Interaction

the dependence of the effect of one factor (such as environment) on another factor (such as heredity)

Molecular Genetics the subfield of biology that studies the

molecular structure and function of genes

Environmental Influence

Experience affects brain development

Impoverishedenvironment

Rat braincell

Rat braincell

Enrichedenvironment