Lifespan Development: Key Concepts in Developmental Psychology

Developmental Psychology

Overview

Developmental psychology is the scientific study of human physical, cognitive, social, and behavioural characteristics across the lifespan. It seeks to understand how we become who we are and why individuals develop differently even in similar environments.

• Methods:

  • Cross-sectional designs: Compare individuals of different ages at one point in time.

  • Cohort effects: Differences due to generational or historical context.

  • Longitudinal design: Follows the same individuals over time to observe changes.

Prenatal Development

Stages and Age of Viability

Prenatal development involves critical periods where organs and systems form. The age of viability (when survival outside the womb is possible) is around 22 weeks.

Weeks	Major Developments
1-8	Heart, CNS, limbs, eyes, ears begin forming
8-22	Further development of organs, increasing viability
22-38	Final maturation of CNS, lungs, and other systems

Research Example: Speech Sound Recognition

• Study: Mothers read Cat in the Hat aloud during last 6 weeks of pregnancy.

• Procedure: Babies tested 2 days after birth; sucking rate measured as they heard speech sounds.

• Results: Babies whose mothers read aloud changed their sucking pattern, indicating recognition/preference. Control group showed no change.

Teratogens

Definition and Examples

Teratogens are substances or environmental factors that can harm a developing fetus, causing growth problems, birth defects, or miscarriage. Effects depend on timing of exposure.

• Alcohol: Fetal Alcohol Spectrum Disorder (FASD)

• Tobacco: Low birth weight

• Viruses: Zika

• Bacteria/Parasites: Toxoplasmosis

• Radiation

• Pollution: Lead, mercury, pesticides

• Drugs: Prescription/illegal (e.g., Accutane, Thalidomide)

Case Studies

• Fluoride Exposure: Higher maternal fluoride linked to slightly lower IQ scores in children (Green et al., 2019).

• Thalidomide: Drug for morning sickness, withdrawn in 1962 due to severe birth defects; led to new safety protocols.

• Teflon & C-8: "Forever chemicals" with potential developmental risks.

Infancy & Childhood

Motor Development

• Milestones (e.g., rolling over, sitting, walking) indicate when 50% of children can perform a skill.

• Driven by biological maturation and environmental exploration.

Visual Perception

• Newborns prefer patterns with contours and edges.

• Can imitate adult expressions, foundational for social skills.

Kindchenschema (Baby Schema)

• Humans are predisposed to protect and nurture infants due to physical features (large eyes, round cheeks, soft movements) that trigger caregiving and affection.

• Evolutionary basis for attachment and care.

Attachment

Definition and Theories

• Attachment: Emotional bond between child and caregiver, evidenced by seeking closeness and distress on separation.

• Konrad Lorenz: Imprinting in goslings during critical period.

• Harlow's Monkeys: Preference for comfort over food; contact comfort is crucial.

• Bowlby: Attachment is innate, evolved for survival; reciprocity builds attachment.

Ainsworth's Strange Situation & Attachment Styles

Style	Characteristics
Secure	Uses mom as base, distressed on separation, comforted on return
Avoidant	Does not cry on separation, avoids mom on return
Ambivalent	Distressed on separation, ambivalent on return
Disorganized-disoriented	Inconsistent, contradictory behaviour

Consequences & Criticisms

• Secure attachment linked to social competence, fewer psychological difficulties, better relationships.

• Criticisms: Cultural variation, temperament, genetic factors may influence attachment.

Parenting

Parenting Styles & Social Development

Style	Parent Behaviour	Child Outcome
Authoritarian	Rigid, punitive, strict	Withdrawn, unfriendly
Permissive	Lax, inconsistent, undemanding	Immature, moody, dependent
Uninvolved	Detached, only provides basic needs	Indifferent, rejecting
Authoritative	Firm, sets limits, encourages independence	Socially skilled, independent

Morality & Motivation

• Attachment system: Feeling safe and secure is foundational.

• Caregiving system: Responding to needs builds empathy and moral values.

• Inductive discipline: Explaining consequences, activating empathy, supporting internal moral values.

Cognitive Development: Piaget's Theory

Stages of Cognitive Development

• Sensorimotor (Birth-2 yrs): Understanding through senses and actions; develops object permanence.

• Preoperational (2-7 yrs): Language, symbolic thinking, egocentrism.

• Concrete Operational (7-12 yrs): Logical thinking, conservation, reversibility.

• Formal Operational (12+ yrs): Abstract and logical thinking.

Key Processes

• Assimilation: Fitting new experiences into existing schemas.

• Accommodation: Changing schemas when new experiences don't fit.

Self-awareness & Theory of Mind

• Self-awareness emerges around 18-24 months.

• Theory of mind (understanding others' perspectives) emerges around 4-5 years.

Early Social Understanding

• Infants and toddlers recognize when someone needs help, prefer helpers, and show fairness.

• "Helper stage" spans ~14 months to 7 years and is seen across cultures.

Adolescence

Emotion Regulation

• Emotions are intense; flexibility in coping strategies is key.

• Cognitive reframing helps delay gratification and focus on long-term goals.

Risky Decisions & Peer Influence

• Adolescents are prone to impulsivity due to peer pressure and developing brain systems.

• Peer presence increases risk-taking; adults are less affected.

Cognitive Development in Adolescence

• Adolescent egocentrism: Heightened self-focus.

• Imaginary audience: Belief that others are constantly observing them.

• Personal fables: Belief in uniqueness and invulnerability.

Social Development: Identity & Relationships

• Identity formation: Figuring out one's role, exploring careers, beliefs, and values.

• Peer groups: Friendships and social dynamics are top priorities.

• Romantic relationships: Teens begin exploring emotional and physical intimacy; risk of psychological and sexual aggression.

Adulthood

Transitions of Life

• Emerging adulthood (18-24): Still determining identity, career path; peak health.

• Middle adulthood (20s-40s): Physical declines minor, body less efficient, more susceptible to disease.

Marriage & Parenting

• Relationships provide health, happiness, and support, but 40% of Canadian marriages end in divorce.

• Marital satisfaction often declines after children are born, especially for high SES and younger parents.

• "Sandwich generation": caring for children and aging parents.

Protective Factors for Marital Satisfaction

• Fair division of labor, good communication, social support, realistic expectations, strong pre-baby relationship, mental health, and structural support (e.g., paid leave).

Late Adulthood: Happiness & Relationships

Socioemotional Selectivity Theory

• Older adults focus on positive, meaningful experiences and relationships.

• Better attention to positive emotions, optimism, and wisdom.

• Goals shift toward rewarding experiences.

The Ageing Brain

• Declines in memory, reasoning, and decision-making are common, but cognitive training (e.g., video games) can improve functioning.