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The Study of Human Development

Developmental psychology• Examines physical, cognitive, and socioemotional change

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The Study of Human Development

THREE DEBATES

• Stages or continuity

• Sensitive and critical periods

• Hereditary and environmental influences

• Nature and nurture

• Stability and change

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CHROMOSOMES, DNA, AND GENES

Every cell in your body, except red blood cells and sex cells (sperm or egg), contains a full set of 23 chromosome pairs. These 23 chromosome pairs contain the full blueprint for you as a complete, unique person. The primary component of each chromosome is a single, tightly wound molecule of DNA. Within that DNA are around 21,000 genes, each determining specific traits.

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Genetics, Conception, andPrenatal Development

CHROMOSOMES AND GENES

How exactly did you get your genes from your biological parents?

• Genes are found in chromosomes.

• Chromosomes inherited from biological parents.

• Sperm and egg both contain 23 chromosomes = 23 pairs.

• Twenty-third chromosome pair determines genetic sex.

• XX = female; XY = male

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Genetics, Conception, andPrenatal Development

FROM ZYGOTE TO EMBRYO TO FETUS

Zygote

• Is single cell formed by union of sperm cell and egg

• Travels down fallopian tube while dividing into more cells

Multiples

• Monozygotic twins develop from one egg inseminated at conception.

• Dizygotic twins occur when two eggs are inseminated by two different sperm.

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Genetics, Conception, andPrenatal DevelopmentGerminal Period (Conception to end of 2nd week)• Implanting in uterine wall; rapid growth

Embryo Period (3rd to 8th week)• Cell differentiation; formation of major organs and systems

begin• Heart begins to beat; spinal cord and intestinal systems

develop by end of period

Fetal Period (2nd month to birth)• Rapid weight gain; clear sleep-wake cycles; all organs,

systems, and structures fully developed at birth• Brain weight one-quarter of adult size

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Prenatal Development and Periodsof Critical Growth

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Genetics, Conception, andPrenatal Development

Teratogens

• Embryo not protected from all environmental dangers.

• Teratogens can damage a zygote, embryo, or fetus.

• Damage depends on the agent, timing, and duration of exposure.

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The photograph at left shows the brain of an infant girl who died at 6 weeks. The mother was categorized as a chronic alcoholic. The child’s head circumference was 27 centimeters at birth and did not grow at all during her 6 weeks of life (normal head circumference is approximately 35 centimeters - about 13 and 3/4 inches).

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Fetal Alcohol Syndrome (FAS)

Male infant born at term and died at 10 weeks due to a sudden cardiac arrest (see picture at right). The mother's alcohol drinking included   up to a gallon of wine at a time several times a week. The child had hydrocephalus (excess water in the brain) and typical facial features of fetal alcohol syndrome (FAS). The cerebellum (which controls coordination and movement) was "extremely small and poorly shaped (see picture at right)." The brainstem (responsible for processes such as breathing and body temperature) was also grossly malformed.

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Child with FAS, illustrating many features in the drawing. Such children may also have cardiovascular and limb defects.

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Can you identify the

potential effects of each of these

teratogens?

Alcohol

Caffeine

Cocaine

LeadLithium

LSD

Mercury

Nicotine

Radiation exposure

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Infancy and Child Development

Synaptic pruning

• Increase in neural connections is not uniform in brain

• Unused synaptic connections eliminated

• Decrease in neural connection by 40 to 50 percent by puberty

Rosenzweig’s rats

• Rosenzweig and colleagues demonstrate how environment influences animal brain development.

• Rats with enriched environment experienced greater increases in brain weight and synaptic connections.

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Infancy and Child Development

PIAGET AND COGNITIVE DEVELOPMENT

Schema

• Collection of ideas that represent a basic unit of understanding

Assimilation

• Using existing information and ideas to understand new knowledge and experiences

Accommodation

• Restructuring of old ideas to make a place for new information

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Ch

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Blo

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Assessing Child’s Stage of Cognitive Development

Child playing peekaboo, ˝ Peter Polak/Fotolia.com; Child playing vet with Teddy bear, ˝ Gina Sanders/Fotolia.com; Object permanence test, Doug Goodman/Science Source; Blocks silo, Thinkstock; Teenage girl writing on chalkboard, Creatas/Thinkstock; Young Asian boy pouring cooking oil into cake batter, iStockphoto/Thinkstock; Hands open, iStockphoto/Thinkstock; Piaget Conservation-Girl with milk glasses, Bianca Moscatelli/Worth Publishers

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Infancy and Child Development

ATTACHMENT

Attachment

• Degree to which infant feels emotional connection with primary caregivers

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Attachment

Freud

Baby attaches to mother because mom provides oral stimulation

Attachment is due to feeding only.

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Infancy and Child Development

ERIKSON’S PSYCHOSOCIAL STAGES

Erikson

• Proposed human development marked by eight psychological stages from infancy to old age

• Suggested each stage marked by developmental task or emotional crisis to be resolved

• Unsuccessful resolution results in difficulty at next stage

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Infancy and Child Development

ERIKSON’S EIGHT STAGES

Trust versus mistrust

Identity versus role confusion

Intimacy versus Isolation

Check Table 8.2 for a discussion of each stage and its positive and negative resolutions.

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Erikson

Trust vs. mistrustBirth to 1 year

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Harry Harlow

Harry and Margaret Harlow found that contact comfort forms the basis of attachment in rhesus monkeys

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Mary AinsworthThe Strange Situation

Human infants exhibit separation anxiety and stranger anxiety once attachment has formed, at about 6 to 8 months of age

Separation anxiety

• fear and distress shown when parent leaves

Stranger anxiety

• fear of strangers

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Secure attachmentUse mother as a secure base for exploring

Distressed by separation from caregivers, greet caregivers when they return

More cooperative and content than other infants

Display better social skills as preschool children

Insecure Avoidant attachmentNot responsive to mother, not troubled when she leaves

May actively avoid contact with mother after separation

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Insecure Ambivalent attachment

Seek close contact with mother, and tend not to branch out and explore

After separation, may display anger toward mother; not easily comforted

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Adolescence

PHYSICAL AND COGNITIVE DEVELOPMENT

Adolescence

Puberty

Menarche

Spermarche

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Adolescence

PHYSICAL AND COGNITIVE DEVELOPMENT

Timing and effects of maturation

• Early maturing girls: More negative outcomes; social anxiety, higher risk of emotional problems and unhealthy and delinquent behaviors; lower self-confidence

• Early maturing boys: Generally a more positive experience; however: aggressive behavior, cheating, temper tantrums common

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Adolescence

PHYSICAL AND COGNITIVE DEVELOPMENT

Adolescent egocentrism

• Involves intense focus on self and feelings of immortality

• Influences increased risky behaviors

• Personal Fable

• Imaginary Audience

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Adolescence

Adolescent brain

• Significant limbic system development compared to prefrontal cortex can lead to increase in risk-taking behavior.

• Increased myelination of axons in prefrontal cortex which is not yet fully developed

• Adolescent may not foresee the possible consequences of reward-seeking activities.

Should this influence decision about teenagers and the death penalty?

Teen inmates stand in line at a Texas prison facility. As of 2005, defendants being tried for crimes committed before age 18 are no longer candidates for the death penalty.

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SOCIOEMOTIONAL DEVELOPMENT IN ADOLESCENCE

Erikson’s stage of ego identity versus role confusion

• Involves adolescent identity formation and trying out new roles

• Influenced by positive resolution and success at earlier stages

• Positive resolution = Stronger sense of values, beliefs, and goals

• Negative resolution = Role confusion

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SOCIOEMOTIONAL DEVELOPMENT IN

ADOLESCENCE

Relationships between teens and parents are generally positive, but most involve some degree of conflict.

Many disputes center on everyday issues, like clothing and chores, but the seemingly endless bickering does have a deeper meaning.

The adolescent is breaking away from his parents, establishing himself as an autonomous person.

Parents and Friends

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Parenting Styles

Baumrind

2 factors:

Discipline and control

Love and affection

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SocializationParenting Styles

Authoritarian parentsMake arbitrary rules, expect unquestioning obedience, punish transgressions

Authoritative parentsSet high but realistic standards, reason with the child, enforce limits, and encourage open communication and independence

Permissive parentsMake few rules or demands, allow children to make their own decisions and control their own behavior

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SocializationParenting Styles - Outcomes

Children with authoritarian parents: withdrawn, anxious, and unhappy

Children with authoritative parents: happier; have higher self-esteem; more self-reliant, socially competent; more responsible than their peers

Children with permissive parents: most immature, impulsive, and dependent, and the least self-reliant and self-controlled