Lifespan Development: Key Concepts in Developmental Psychology

Lifespan Development

Introduction to Developmental Psychology

Developmental psychology is the scientific study of human physical, cognitive, social, and behavioral characteristics across the lifespan. It explores how people change and grow from conception through old age, using various research methods to understand these processes.

• Cross-sectional designs: Compare individuals of different ages at one point in time to identify age-related differences.

• Cohort effects: Differences that result from the specific experiences of a particular age group or generation.

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

Prenatal Development

Research Example: Fetal Learning

Studies show that babies can learn and recognize speech sounds before birth. For example, infants whose mothers read The Cat in the Hat aloud during pregnancy showed changes in sucking patterns after birth, indicating recognition and preference for familiar sounds.

• Independent Variable (IV): Maternal reading of a specific story during pregnancy.

• Dependent Variable (DV): Changes in infant sucking rate as an indicator of preference.

• Result: Babies exposed to the story showed recognition; control group did not.

Teratogens

Teratogens are substances or environmental factors that can harm a developing fetus, leading to growth problems, birth defects, or miscarriage.

• Alcohol: Can cause Fetal Alcohol Spectrum Disorder (FASD).

• Tobacco: Associated with low birth weight.

• Viruses: e.g., Zika virus.

• Bacteria/Parasites: e.g., toxoplasmosis.

• Radiation, Pollution, Drugs: e.g., lead, mercury, accutane.

Example: Thalidomide, a drug prescribed for morning sickness, caused severe birth defects and led to new safety protocols.

Maternal Fluoride Exposure and IQ

Research (Green et al., 2019) found that higher maternal fluoride exposure was associated with slightly lower IQ scores in children aged 3 to 4.

• Sample: 512 mother-child pairs.

• Finding: Small decrease in IQ points linked to higher fluoride exposure.

Infancy and Childhood

Physical and Perceptual Development

Development in infancy and childhood is driven by biological maturation and active exploration of the environment, with cultural differences influencing activity levels.

• Visual perception: Newborns prefer patterns with contours and edges and can imitate adult expressions, laying the foundation for social interaction.

• Kindchenschema: Physical features in babies (large eyes, round cheeks) trigger caregiving and affection in adults, an evolutionary adaptation.

Attachment

Attachment Theory

Attachment is the emotional bond between a child and caregiver, providing evolutionary advantages such as safety and security. Early studies by Konrad Lorenz and Harry Harlow demonstrated the importance of comfort and closeness in attachment formation.

• Secure attachment: Child uses caregiver as a base for exploration, is distressed when caregiver leaves, and seeks comfort upon return.

• Avoidant attachment: Child does not cry when caregiver leaves and avoids them upon return.

• Ambivalent attachment: Child is distressed when caregiver leaves but ambivalent upon return.

• Disorganized-disoriented attachment: Child shows inconsistent, contradictory behavior.

Consequences: Securely attached children tend to be more socially and emotionally competent, have fewer psychological difficulties, and experience more successful relationships later in life.

Criticisms of Attachment Theory

• Cultural differences: Parenting practices vary across cultures, challenging the universality of attachment classifications.

• Temperament: Theory may not account for individual differences in temperament.

• Genetic factors: Shared genes between caregivers and infants may influence attachment.

Parenting Styles and Social Development

Parenting Styles

Parenting styles influence children's emotional and social development. Four main styles are identified:

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

Parenting, Morality, and Motivation

• Attachment system: Focuses on safety and security.

• Caregiving system: Responds to child's needs when attachment is secure.

• Operant conditioning: Parents use rewards and punishments, but behaviors may not last without intrinsic motivation.

• Conditional love: Can lead to resentment and internal pressure; children may feel worthy only if they perform.

• Inductive discipline: Explaining how actions affect others activates empathy and supports internal moral values.

Cognitive Development in Infancy and Childhood

Jean Piaget's Theory of Cognitive Development

Piaget proposed that children progress through stages of cognitive development, adapting to new information through assimilation and accommodation.

• Assimilation: Incorporating new experiences into existing schemas.

• Accommodation: Modifying schemas when new experiences do not fit.

Stage	Age Range	Main Features
Sensorimotor	Birth to 2 years	Understanding through physical interaction; development of object permanence
Preoperational	2 to 7 years	Language and symbolic thinking; egocentric thought
Concrete Operational	7 to 12 years	Logical thinking; principle of conservation; reversibility; bound to concrete reality
Formal Operational	12 years to adulthood	Abstract and logical thinking

Self-Awareness and Theory of Mind

• Self-awareness: Emerges around 18-24 months; ability to recognize oneself as an individual.

• Theory of mind: Develops around 4-5 years; understanding that others have thoughts and perspectives different from one's own.

• Egocentrism: Common in early childhood; children view the world from their own perspective.

Early Social Understanding

• Infants and toddlers can recognize when someone needs help, prefer helpers, and show an early sense of fairness.

• "Helper stage" occurs from 14 months to 7 years and is observed across cultures.

Adolescence

Emotional and Cognitive Development

Adolescence is a transitional period marked by intense emotions, developing cognitive abilities, and increased risk-taking.

• Emotion regulation: Still developing; flexibility in strategies is important to reduce risk of anxiety and depression.

• Cognitive reframing: Changing perspective on failure or threat helps focus on long-term goals.

• Risky decisions: Adolescents are prone to impulsivity due to peer influence and an underdeveloped prefrontal cortex.

Peer Influence and Risk-Taking

• Peer presence increases risk-taking behavior in adolescents (e.g., more crashes in driving simulations with peers).

• Adults are less affected by peer presence in risk-taking scenarios.

Cognitive Development in Adolescence

• Abstract thinking: Formal operational stage enables reasoning about hypothetical and abstract concepts.

• Adolescent egocentrism: Heightened self-focus; belief that others are constantly observing and judging them (imaginary audience).

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

Social Development: Identity and Relationships

• Identity formation: Adolescents explore careers, beliefs, and values, often experiencing identity crises.

• Peer groups: Friendships and cliques are central; social exclusion can lead to shame and alternative social groups.

• Romantic relationships: Adolescents begin exploring emotional and physical intimacy, with risks of psychological and sexual aggression.

Adulthood

Transitions and Milestones

• Emerging adulthood (18-24): Period of identity exploration and peak health.

• Middle adulthood (20s to 40s): Perceived as the best years; minor physical declines begin.

Marriage and Relationships

• Relationships are associated with greater health, happiness, and longevity.

• 40% of Canadian marriages end in divorce.

"Four Horsemen" of Relationship Breakdown	Description
Criticism	Picking out flaws, expressing disappointment
Defensiveness	Responding to attacks with counterattacks
Contempt	Eye rolling, sarcasm, cutting tones
Stonewalling	Shutting down verbally and emotionally

Parenthood and Marital Satisfaction

• Marital satisfaction typically decreases after the birth of the first child and remains low until children leave home.

• High SES and younger parents report lower satisfaction.

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

• Protective factors: Fair division of labor, good communication, social support, realistic expectations, strong pre-baby relationship, mental health, and structural support.

Late Adulthood

Happiness and Relationships

Older adults focus on positive, meaningful experiences, preferring activities that emphasize joy and connection. Socioemotional selectivity theory explains this shift toward meaningful goals and optimism.

• Older adults are more optimistic and better at handling adversity due to wisdom and experience.

The Ageing Brain

• Age-related changes include reduction in white and grey matter, affecting memory and decision-making.

• Dementia: Disruption of mental functioning, memory loss, and poor judgment (affects 14% of those 71+).

• Alzheimer's disease: Degenerative and terminal; buildup of tau protein kills nerve cells.

• Prevention: Physical activity, cognitive engagement, healthy diet, and social connection can reduce risk.

Gaming in Late Adulthood

• Video games can improve task switching, short-term memory, and reasoning in older adults.

• Effects last several months; research is ongoing (e.g., studies on Nintendo Wii).

Additional info: Piaget's stages, attachment theory, and parenting styles are foundational concepts in developmental psychology and are widely applied in educational, clinical, and social contexts.