Lifespan Development: Childhood and Beyond – Study Notes for Introduction to Psychology

Lifespan Development

Definition and Overview

Development refers to the sequence of age-related changes that occur as individuals progress from conception to death. Developmental psychology studies these changes across four broad periods:

• Prenatal

• Childhood

• Adolescence

• Adulthood

Developmental psychology examines changes in three main domains:

• Physical: Changes in the body, such as muscle growth, coordination, and control.

• Cognitive: Changes in thinking, decision making, and problem solving.

• Social: Changes in how individuals interact with others and function in society.

One of the central debates in developmental psychology is Nature vs. Nurture:

• Nature: Genetic and inborn characteristics.

• Nurture: Environmental influences and experiences.

Research Considerations in Developmental Psychology

• Parental Consent: Required for minors to participate in research; minors must also assent.

• Post Hoc Fallacy: Mistakenly assuming that because one event follows another, the first caused the second.

• Bidirectional Influences: Development both influences and is influenced by interactions with the environment.

• Cohort Effects: Differences among groups of people who experience the same event (e.g., COVID-19) at the same time.

• Longitudinal vs. Cross-Sectional Studies:

  • Longitudinal: Follows the same individuals over a long period.

  • Cross-Sectional: Compares individuals of different ages at one point in time.

Prenatal Development

Conception and Early Development

• Conception: Fertilization of the egg by sperm.

• Women are born with all their eggs; men produce sperm throughout life.

Stages of Prenatal Development

• Germinal Stage (Stage 1):

  • Zygote: Fertilized egg; begins dividing and attaches to uterine wall about 10 days after conception.

  • Highly vulnerable; many pregnancies end before the woman knows she is pregnant.

  • Twins:

    • Monozygotic: Identical twins from one egg splitting.

    • Dizygotic: Fraternal twins from two eggs fertilized by two sperm.

• Embryonic Stage (Stage 2):

  • From 2 weeks after conception to the end of the second month.

  • Organ systems begin to develop.

  • Growth patterns:

    • Cephalocaudal: Head-to-tail development.

    • Proximodistal: Center-outward development.

• Fetal Stage (Stage 3):

  • From 9 weeks after conception to birth.

  • Rapid body growth and cell differentiation.

  • Facial features become defined by 4 months.

  • Potential problems:

    • Premature Birth: Before 36 weeks; viability (chance of survival) increases after 25 weeks.

    • Genetic Disorders

    • Environmental Factors (Teratogens):

      • Drugs (legal and illicit), e.g., thalidomide, alcohol (can cause Fetal Alcohol Syndrome), tobacco.

      • Maternal illness and malnutrition.

Birth and Newborns

Reflexes and Early Abilities

• Newborns possess reflexes that aid survival:

  • Withdrawal from pain

  • Moving face if breathing is obstructed

  • Rooting for nipple

  • Swallowing milk

• Seek social stimulation (prefer faces)

• Recognize mother's scent and voice

Infancy and Childhood

Physical and Brain Development

• Most rapid brain growth (ages 3-6) occurs in the frontal lobes, supporting rational planning and behavioral control.

• Motor development milestones:

  • Sitting unsupported (~6 months)

  • Crawling (8-9 months)

  • Walking/talking begins (~12 months)

  • Walking independently (~15 months)

  • These milestones cannot be rushed; genetic and environmental factors both play roles.

• Critical Periods: Times when certain experiences have a particularly strong impact on development (e.g., language acquisition).

Cognitive Development: Piaget's Theory

• Jean Piaget (1896-1980): Studied how children's thinking differs from adults'.

• Children develop schemas (mental models) to organize experiences.

• Assimilation: Adding new information to existing schemas.

• Accommodation: Creating new schemas for information that doesn't fit existing ones.

• Development is driven by the struggle to make sense of experiences (equilibration and disequilibration).

Piaget's Four Stages of Cognitive Development

Stage	Age Range	Key Features
Sensorimotor	Birth – 2 years	Experience world through senses Develop object permanence (~8 months): understanding objects exist even when out of sight Stranger anxiety develops (~8 months)
Preoperational	2 – 6/7 years	Use words and images to represent things Pretend play Egocentrism: difficulty seeing from others' perspectives Develop theory of mind: understanding others have thoughts and feelings
Concrete Operational	7 – 11 years	Logical thinking about concrete events Understand conservation: quantity remains the same despite changes in shape
Formal Operational	12+ years	Abstract reasoning and systematic logic

• Take-home message: Young children are not mini-adults; their logic and understanding are qualitatively different.

Vygotsky's Sociocultural Theory

• Scaffolding: Parents and others provide support for learning, gradually removing help as the child becomes more competent.

• Zone of Proximal Development (ZPD): The range of tasks a child can perform with guidance but not alone.

• Development rates vary; social interaction is crucial for cognitive growth.

Social Development in Infancy and Childhood

Attachment and Social Bonds

• Humans are social from birth; infants prefer face-like stimuli.

• Imprinting (Lorenz): Early, strong attachment to the first moving object seen (in animals).

• Attachment: Emotional bond that keeps infants close to caregivers, enhancing survival.

• Body contact (Harlow & Harlow): Monkeys preferred soft, comforting "mothers" over those that provided food, highlighting the importance of touch in attachment.

• Familiarity: Repeated exposure fosters fondness and a sense of safety.

Attachment Styles (Ainsworth)

Attachment Style	Characteristics
Secure	Healthy balance of closeness and independence; upset when caregiver leaves but recovers quickly upon return.
Insecure-Anxious	Clingy, less likely to explore, very upset when caregiver leaves, difficult to comfort.
Insecure-Avoidant	Indifferent to caregiver's departure and return; may avoid caregiver.
Disorganized	Combination of behaviors; confused or contradictory responses (rare, ~2%).

Temperament and Parenting Styles

• Temperament: A person's characteristic emotional reactivity and intensity (e.g., easy, slow-to-warm-up, difficult).

• Parenting Styles:

  • Permissive: Lenient, little discipline, affectionate.

  • Authoritarian: Strict, punishing, little affection.

  • Authoritative: Supportive, sets firm limits.

  • Indifferent: Uninvolved.

• Parenting style effectiveness can depend on the child's temperament.

Attachment Deprivation

• Most children are resilient, but some may experience ongoing effects from attachment deprivation:

  • Hypervigilance: Constantly scanning the environment for threats.

  • Quick Startle Response: Easily startled or jumpy.

  • Slow Serotonin Response: Difficulty calming aggression.