Lifespan Development: Key Concepts in Developmental Psychology

Lifespan Development

Developmental Psychology

Developmental psychology is the scientific study of how humans change physically, cognitively, socially, and behaviorally throughout their lives. 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 the unique experiences of a particular age group.

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

Prenatal Development

Stages and Milestones

Prenatal development involves a series of stages from conception to birth, with critical periods for the development of organs and systems. The age of viability (when a fetus can survive outside the womb) is around 22 weeks.

Weeks	Major Developments
1-2	Fertilization, zygote formation
3-8	Organogenesis (CNS, heart, limbs, eyes, ears, palate)
9-38	Growth and maturation of organs

Additional info: The timing of exposure to harmful substances (teratogens) is crucial, as different organs are vulnerable at different stages.

Prenatal Development: Research Example

• Study: Can babies learn and recognize speech sounds before birth?

• IV: Mothers read Cat in the Hat aloud daily during the last 6 weeks of pregnancy vs. no reading.

• Procedure: Babies tested 2 days after birth; sucking rate measured as an indicator of preference.

• Results: Babies whose mothers read the story changed their sucking pattern, indicating recognition and preference.

Teratogens

Teratogens are substances or environmental factors that can harm a developing fetus, leading to birth defects, growth problems, or miscarriage. The effect depends on the timing of exposure.

• Examples: Alcohol (FASD), tobacco, viruses (Zika), bacteria/parasites (toxoplasmosis), radiation, pollution (lead, mercury), drugs (prescription/illegal), Accutane.

• Low birth weight: Less than 5 lbs 8 oz is considered low birth weight (LBW).

Maternal Fluoride Exposure & IQ Scores

• Study: Green et al., 2019 (YorkU)

• Children born to mothers with higher fluoride exposure had slightly lower IQ scores at ages 3-4.

• Sample: 601 mother-child pairs; 41% lived in fluoridated communities.

Thalidomide

• Drug prescribed for morning sickness, withdrawn in 1962.

• Highly teratogenic: caused limb malformations and other birth defects.

• Led to new safety protocols in Canada; government has not officially apologized for its role.

Teflon & C-8 (Forever Chemicals)

• Exposure to certain industrial chemicals (e.g., C-8) can have long-term health effects, including developmental issues.

Infancy & Childhood

Motor Development

• Milestones (e.g., rolling over, sitting, crawling, walking) occur at varying ages, indicating when 50% of children can perform the skill.

• Driven by biological maturation and influenced by environment and culture.

Visual Perception

• Newborns prefer patterns with contours and edges.

• Can imitate adult expressions, providing a foundation for social interaction skills.

Kindchenschema (Baby Schema)

• Humans are predisposed to find certain infantile features (large eyes, round cheeks, small nose) appealing, triggering caregiving and affection.

• This response is evolutionary and activates reward-related brain regions.

Attachment

Definition and Importance

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

• Early studies (Lorenz, 1965) on imprinting in goslings; deprivation leads to cognitive and emotional impairment.

Harlow's Monkeys

• Infant monkeys preferred comfort (cloth mother) over food (wire mother), highlighting the importance of emotional security.

Bowlby on Attachment

• Attachment is innate and evolved for survival.

• Behaviors like crying, clinging, and smiling attract caregiver attention; reciprocity builds attachment.

Ainsworth's Strange Situation & Attachment Styles

Style	Behavior
Secure	Uses mom as base, distressed when she leaves, comforted on return
Avoidant	Does not cry when mom leaves, avoids her on return
Ambivalent	Distressed when mom leaves, ambivalent on return
Disorganized-disoriented	Inconsistent, contradictory behavior

Consequences of Attachment

• Securely attached children are more socially and emotionally competent, have fewer psychological difficulties, and more successful relationships later in life.

Criticisms of Attachment Theory

• Cultural variations in parenting challenge universality.

• Does not account for temperament.

• Attachment may be influenced by shared genetics.

Parenting

Parenting Styles & Social Development

Style	Parent Behavior	Child Outcome
Authoritarian	Rigid, punitive, strict	Unsociable, unfriendly, withdrawn
Permissive	Lax, inconsistent, undemanding	Immature, moody, dependent, low self-control
Uninvolved	Emotionally detached, only provides basic needs	Indifferent, rejecting
Authoritative	Firm, sets limits, encourages independence	Good social skills, independent, self-reliant

How Parenting Shapes Morality & Motivation

• Attachment system: "Am I safe and secure?"

• Caregiving system: "How can I respond to your needs?"

• Inductive discipline (explaining how actions affect others) works best, activating empathy and supporting internal moral values.

• Conditional love and operant conditioning can lead to resentment and internal pressure.

Cognitive Development in Infancy & Childhood

Jean Piaget's Theory

• Children progress through stages of cognitive development, using schemas (mental frameworks) to make sense of the world.

• Assimilation: Fitting new experiences into existing schemas.

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

Stages of Cognitive Development

• Sensorimotor (0-2 yrs): Understanding through senses and actions; develop object permanence.

• Preoperational (2-7 yrs): Language and symbolic thinking; egocentrism (difficulty seeing others' perspectives).

• Concrete Operational (7-12 yrs): Logical thinking, principle of conservation, reversibility; bound to concrete reality.

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

Self-Awareness & Theory of Mind

• Self-awareness emerges around 18-24 months (recognizing oneself as an individual).

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

Early Social Understanding

• Infants and toddlers can 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 to reducing anxiety and depression risk.

• Cognitive reframing (changing perspective) helps delay gratification and focus on long-term goals.

Risky Decisions & Peer Influence

• Adolescents are prone to impulsive, risky decisions due to peer pressure and an underdeveloped prefrontal cortex (PFC).

• Peers increase risk-taking; adults are less affected by peer presence.

Cognitive Development in Adolescence

• Formal operational thinking enables abstract reasoning.

• Adolescent egocentrism: Heightened self-focus, belief in an "imaginary audience" (others are always watching/judging).

• Personal fables: Belief in the uniqueness of one's thoughts and experiences, leading to feelings of invulnerability.

Social Development: Identity & Relationships

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

• Peer groups: Friendships are a top priority; cliques are dynamic.

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

Adulthood

Transitions of Life

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

• Middle adulthood (20s-40s): Perceived as best years; gradual physical decline, increased disease susceptibility.

Marriage

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

Four Horsemen of the Apocalypse (Relationship Conflict)

Criticism	Picking out flaws, negative comments
Defensiveness	Responding to perceived attacks with counterattacks
Contempt	Eye rolling, sarcasm, cutting tones
Stonewalling	Shutting down verbally and emotionally

Parenthood: Trends & Challenges

• Marital satisfaction highest before first child, declines until children leave home.

• High SES and younger parents report lower satisfaction.

• "Sandwich generation": Caring for both children and aging parents.

Protective Factors for Marital Satisfaction After Children

• 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, greater optimism, and wisdom.

• Seek out situations that elicit positive emotions; goals shift toward meaningful, rewarding experiences.