Chapter 3: Developing Through the Life Span

Developmental Psychology and Its Major Issues

• Definition of Developmental Psychology: This field examines physical, cognitive, and social development across the entire life span of an individual.

• Research Methods in Development:

  • Cross-sectional studies: Researchers compare individuals of different ages at the same single point in time.

  • Longitudinal studies: Researchers follow and retest the same individuals repeatedly over a long period to explore developmental changes.

• The Three Major Issues:

  • Nature and nurture: This focuses on how genetic inheritance (nature) interacts with our experiences (nurture) to influence development. Individuals are formed through the interaction of biological, psychological, and social-cultural forces.

  • Continuity and stages: This asks which parts of development are gradual and continuous (like riding an escalator) and which parts change abruptly in separate stages (like climbing rungs on a ladder). Development is viewed either as a slow, ongoing process or as a process of maturation guided by genetic instructions. Stage theories help focus on the forces and interests affecting individuals at different points in the life span.

  • Stability and change: This deals with which traits persist through life and how people change as they age. Stability provides an individual with their identity, while the ability to change provides hope for a brighter future and allows for adaptation and growth through experience.

Genetic Foundations and Prenatal Development

• Conception Definitions:

  • Chromosomes: Threadlike structures made of DNA molecules that contain the genes. Humans have $23$ pairs, totaling $46$ chromosomes.

  • DNA (deoxyribonucleic acid): A molecule containing the genetic information that makes up the chromosomes.

  • Genes: Biochemical units of heredity that make up the chromosomes; they are specific segments of DNA.

  • Heredity: The genetic transfer of characteristics from parents to offspring.

  • Genome: This represents the complete instructions for making an organism, consisting of all genetic material in the organism's chromosomes.

• Interaction of Heredity and Environment:

  • Interaction: The interplay that occurs when the effect of one factor (such as environment) depends on another factor (such as heredity).

  • Genetically Influenced Traits: These affect how other people respond to an individual.

  • Environmental Triggers: Environments can trigger gene activity. The "environment" includes every external influence, ranging from prenatal nutrition to social support later in life.

• Stages of Prenatal Development:

  • Zygote: A fertilized egg that enters a $2$-week period of rapid cell division and develops into an embryo.

  • Embryo: The developing human organism from about $2$ weeks after fertilization through $8$ weeks.

  • Fetus: The developing human organism from $9$ weeks after conception until birth.

• Prenatal Hazards:

  • Teratogens: Agents, such as chemicals or viruses, that can reach the embryo or fetus during prenatal development and cause harm.

  • Fetal Alcohol Syndrome (FAS): Physical and mental abnormalities in children caused by heavy drinking by the pregnant mother.

The Competent Newborn and Twin Studies

• The Competent Newborn:

  • Newborns arrive with automatic reflexes (simple, automatic responses to sensory stimuli) that support survival.

  • They search for sights and sounds linked to other humans, specifically the mother.

  • They smell and hear well, using sensory equipment to learn about the environment.

  • Temperament: A person's characteristic emotional reactivity and intensity. This is considered biologically rooted.

• Twin and Adoption Studies:

  • These studies help researchers distinguish between heredity and environmental influences.

  • Identical Twins (Monozygotic): Develop from a single fertilized egg that splits into two, creating genetically identical siblings.

  • Fraternal Twins (Dizygotic): Develop from two separate fertilized eggs. They share $50\%$ of their genetic material, making them no more genetically similar than ordinary siblings.

  • Shared Traits: Identical twins are more similar than fraternal twins in abilities, personal traits, and interests.

• Sesquizygotic Twins:

  • These occur when two sperm fertilize a single egg before it splits, resulting in $3$ sets of chromosomes ($1$ from the mother and $2$ from the father).

  • Embryos generally do not survive as $3$ sets of chromosomes are typically incompatible with life.

  • They share between $50\%$ and $100\%$ of their genetic material. They are genetically identical with respect to one parent ($100\%$ of material from either mother or father), but share $50\%$ of the material from the other parent.

  • Only $2$ sets of sesquizygotic twins are documented globally: one in the United States in $2007$ and one in Brisbane, Australia, in $2014$.

Infancy and Childhood: Physical and Cognitive Development

• Maturation: Biological growth processes that lead to orderly changes in behavior. These are mostly independent of experience; maturation sets the basic course, while experience adjusts it.

• Brain Development:

  • Neural networks develop rapidly after birth. An enriched environment increases brain power.

  • From ages $3$ to $6$, the frontal lobes grow rapidly.

  • Pruning Process: A "use it or lose it" mechanism where disuse weakens neural pathways, while stimulation (sights, smells, music, movement) strengthens them.

  • Critical Period: A period early in life when exposure to specific stimuli or experiences is required for proper development.

• Motor Development:

  • Skills develop as muscles and the nervous system mature. The sequence (sit, crawl, walk, run) is universal and guided by genes, though the specific timing varies from child to child.

• Infant Memory:

  • Infants can learn and remember, but "infantile amnesia" refers to the blank space in conscious memory from the earliest years of life.

• Jean Piaget’s Theory of Cognitive Development:

  • Cognition: Mental activities associated with thinking, knowing, remembering, and communicating.

  • Perspective: Children are active thinkers who construct advanced understandings of the world through a series of stages.

  • Schema: A concept or framework that organizes and interprets information.

  • Assimilation: Interpreting new experiences in terms of existing schemas.

  • Accommodation: Adapting current understandings (schemas) to incorporate new information.

Piaget’s Stages of Cognitive Development

• Sensorimotor Stage ($0$ to nearly $2$ years):

  • Description: Experiencing the world through senses and actions (looking, hearing, touching, mouthing, grasping).

  • Milestones: Object permanence (awareness that things continue to exist even when not perceived) and stranger anxiety.

• Preoperational Stage (about $2$ to $6$ or $7$ years):

  • Description: Representing things with words and images; using intuitive rather than logical reasoning.

  • Milestones: Pretend play (thinking in symbols) and egocentrism (difficulty taking another's point of view).

  • Theory of Mind: Developing ideas about one's own and others' mental states. Between ages $3$ and $4\frac{1}{2}$, children realize others may hold false beliefs. By $4$ to $5$, they anticipate friends' false beliefs.

  • The False Belief Task (Sally-Anne Task): Sally puts a marble in a basket and leaves. Anne moves it to a box. To pass, the child must say Sally will look in the basket (where she thinks it is). Failure (saying Sally will look in the box) means the child cannot understand that Sally has a different mental representation.

• Concrete Operational Stage (about $7$ to $11$ years):

  • Description: Thinking logically about concrete events; performing arithmetical operations.

  • Milestones: Conservation (understanding mass, volume, and number remain the same despite shape changes) and mathematical transformations.

• Formal Operational Stage (about $12$ through adulthood):

  • Description: Reasoning abstractly.

  • Milestones: Abstract logic and the potential for mature moral reasoning.

Social Development in Childhood

• Stranger Anxiety: Fear of strangers beginning around $8$ months of age, as infants develop schemas for familiar faces.

• Attachment: An emotional tie with another person; children seek proximity to caregivers and show distress upon separation.

  • Origins of Attachment: Attachment is rooted in comfort and familiarity. A parent provides a "safe haven" and a "secure base."

  • Harlows’ Study: Infant monkeys preferred contact with a soft cloth mother over a wire mother that provided nourishment.

• Temperament Types:

  • Difficult babies: Irritable, intense, and unpredictable.

  • Easy babies: Cheerful, relaxed, with predictable feeding and sleeping schedules.

• Deprivation of Attachment:

  • Failure to attach leads to withdrawal and fear. Extreme trauma can impact the brain and gene expression.

  • 1980s Romanian Orphanage Case: Children outnumbered caregivers $15 \text{ to } 1$. Years later, these children had lower intelligence scores and double the anxiety rates ($40\%$ vs $20\% \text{ in quality foster care}$).

• Parenting Styles:

  • Authoritarian: Coercive; imposes rules and expects obedience. Outcomes: Lower social skill and self-esteem; overreactive brains regarding mistakes.

  • Permissive: Unrestraining; few demands or limits. Outcomes: Higher aggression and immaturity.

  • Negligent: Uninvolved; careless or inattentive. Outcomes: Poor academic and social outcomes.

  • Authoritative: Confrontive; demanding and responsive. Sets rules but encourages open discussion. Outcomes: Highest self-esteem, self-reliance, self-regulation, and social competence.

Adolescence

• Puberty: The period of sexual maturation where a person becomes capable of reproducing. Sequence is universal, though timing varies.

  • Early Maturing Boys: More popular and self-assured, but higher risk for alcohol use, delinquency, and premature sexual activity.

  • Early Maturing Girls: Mismatch between physical and emotional maturity may lead to seeking older companions or experiencing sexual harassment.

• The Teenage Brain: Unused neurons are pruned. The frontal lobe maturation lags behind the limbic system (the emotional center), leading to impulsiveness and risky behavior. (Note: In $2004$, the U.S. Supreme Court declared the juvenile death penalty unconstitutional based on these developmental factors).

• Moral Development (Kohlberg):

  • Preconventional Morality (before age $9$): Focus on self-interest; obey rules to avoid punishment or gain rewards.

  • Conventional Morality (early adolescence): Uphold laws and rules to gain social approval or maintain social order.

  • Postconventional Morality (adolescence and beyond): Actions reflect belief in basic rights and self-defined ethical principles.

• Moral Intuition and Action: Morality is often rooted in automatic intuitions. Moral action feeds moral attitudes, and the ability to delay gratification is linked to positive adulthood outcomes.

Erik Erikson’s Stages of Psychosocial Development

• Infancy (to $1$ year): Trust vs. Mistrust. If needs are met, basic trust develops.

• Toddlerhood ($1$ to $3$ years): Autonomy vs. Shame and Doubt. Learning to do things for themselves.

• Preschool ($3$ to $6$ years): Initiative vs. Guilt. Initiating tasks and plans.

• Elementary School ($6$ years to puberty): Competence vs. Inferiority. Pleasure of applying themselves to tasks.

• Adolescence (teens into $20$s): Identity vs. Role Confusion. Testing and integrating roles to form a sense of self.

• Young Adulthood ($20$s to early $40$s): Intimacy vs. Isolation. Struggling to form close relationships.

• Middle Adulthood ($40$s to $60$s): Generativity vs. Stagnation. Contributing to the world (work/family).

• Late Adulthood (late $60$s and up): Integrity vs. Despair. Reflecting on life with satisfaction or failure.

Adulthood

• Life Stages:

  • Early Adulthood: Twenties and thirties. Peak muscular strength, reaction time, and cardiac output occurs in the mid-twenties.

  • Middle Adulthood: Ages $30$ to $65$. Physical vigor linked to health/exercise. Decline in fertility occurs (menopause in women; decreased sperm count/testosterone in men).

  • Late Adulthood: years after age $65$.

• Late Adulthood Physical Changes:

  • Vision: Difficulty with fine details and adapting to light changes.

  • Brain: Small, gradual net loss of cells impacting memory and problem solving.

  • Immune System: Weakens, increasing risk of life-threatening ailments, though older adults suffer fewer short-term ailments (like colds).

  • Exercise: Slows aging and maintains telomeres.

• Cognitive Aging and Memory:

  • Early Adulthood: Peak for learning and memory.

  • Middle Adulthood: Decline in recall (active retrieval) but stable recognition (identifying learned info).

  • Late Adulthood: Better retention of meaningful info; longer word production time. Terminal decline occurs in the last $4$ years of life.

• Well-Being: Identity and self-esteem grow stronger from teens to midlife. Positive feelings grow after midlife; negative feelings decline. Older adults report less attachment anxiety and stress.

Death and Dying

• Grief: Most severe when death is sudden or occurs before the expected "social clock." Reactions vary by culture.

• Grief Myths: Immediately expressing grief does not necessarily purge it faster. Adjustment time is similar with or without professional grief counseling.

• Dignity: Facing death with openness helps complete the life cycle with a sense of unity and meaning.