Human Development: Structured Study Notes for Psychology Students

Human Development

Introduction to Developmental Psychology

Developmental psychology is the scientific study of how and why human behavior changes across the lifespan. It examines physical maturation, environmental experiences, and the interaction between both.

• Physical maturation: Biological growth and changes in the body.

• Experience/environment: Learning and adaptation through life events.

• Both: Most changes result from a combination of biological and environmental factors.

Nature vs. Nurture

Gene-Environment Interaction

Nature and nurture interact throughout development, with the effect of one depending on the contribution of the other.

• MAOA gene example: Research shows that individuals with both the low-MAOA gene and a history of childhood maltreatment are at heightened risk for antisocial behavior. However, the gene alone or maltreatment alone does not increase risk.

Nature via Nurture (Niche Picking)

• Genetic predispositions can influence the environments children seek out and create.

• Example: An outgoing child may seek social opportunities, which further reinforce their extroverted tendencies.

Gene Expression and Epigenetics

• Environmental experiences can turn genes on and off, affecting traits and behaviors.

• Gene expression is dynamic; genes that activate may not stay active (epigenetics).

• Example: Stressful events can trigger gene expression related to anxiety or mental illness.

Studying Development

Research Designs

• Cross-Sectional Design: Examines people of different ages at a single point in time. Cannot control for cohort effects.

• Longitudinal Design: Follows the same group over multiple occasions, allowing study of changes over time. More costly and time-consuming; risk of participant attrition.

Post Hoc Fallacy

• Assuming that because one event follows another, it must be the cause.

• Example: Correlating childhood shyness with becoming an engineer, or milk drinking with serial killers, is a logical error.

Bidirectional Influences

• Development is a two-way street: parents influence children, and children influence parents.

• Unidirectional explanations are incomplete.

Physical and Motor Development

Conception and Prenatal Development

• Prenatal period: Before birth, when the body acquires its basic form and structure.

• Conception: Sperm fertilizes egg to produce a zygote.

Three Stages of Prenatal Development

Stage	Timeframe	Description
Germinal	0-2 weeks	Zygote divides and forms blastocyst.
Embryonic	3-8 weeks	Cells start to assume different functions; major organs begin to take shape.
Fetal	9 weeks-birth	Physical maturation; growth and development of organs.

Obstacles to Normal Fetal Development

• Premature birth: Before 36 weeks; higher risk of complications.

• Low birth weight: Less than 5.5 lbs; increased risk of health and developmental issues.

• Exposure to teratogens: Harmful substances (drugs, alcohol, infections) can disrupt development.

• Biological influences: Genetic disorders, errors in cell division (e.g., Down syndrome, Klinefelter syndrome).

Infant Motor Development

• Reflexes: Automatic motor behaviors triggered by specific stimuli (e.g., sucking, rooting reflex).

• Motor behavior: Self-initiated movement influenced by maturation, culture, and parenting.

Growth and Physical Development

Childhood

• Growth spurts occur every 30 to 55 days in children ages 3 to 16.

Adolescence

• Profound physical and hormonal changes.

• Puberty: sexual maturation, development of primary and secondary sex characteristics.

• Menarche: onset of menstruation.

Adulthood

• Fertility declines in middle adulthood; menopause marks end of reproductive potential.

• Men experience gradual decline in sperm production and testosterone.

• Risks increase for having children later in life.

Major Theories of Cognitive Development

Stage-like vs. Continuous Change

• Stage-like: Sudden spurts in knowledge followed by stability.

• Continuous: Gradual, incremental changes.

Domain-General vs. Domain-Specific

• Domain-general: Changes affect most or all areas of cognitive functioning.

• Domain-specific: Skills develop independently and at different rates.

Sources of Learning

• Physical experience

• Social interaction

• Biological maturation

Piaget's Theory of Cognitive Development

• Sensorimotor (0-2 yrs): No thought beyond immediate experiences.

• Preoperational (2-7 yrs): Use symbols, egocentric, limited mental transformations.

• Concrete operational (7-11 yrs): Can perform mental transformations on concrete objects.

• Formal operational (11+ yrs): Abstract and hypothetical reasoning.

Children seek equilibration (balance between experience and understanding). Learning involves:

• Assimilation: Absorbing new experiences into current knowledge structures.

• Accommodation: Altering beliefs to make them compatible with experience.

Pros and Cons of Piaget's Theory

• Pros: Landmark theory; advanced understanding of cognitive development.

• Cons: Development is more continuous and less domain-general than Piaget assumed; relied heavily on language and task demands.

Vygotsky's Theory of Development

• Emphasizes social and cultural factors in learning.

• Scaffolding: Parents provide initial assistance, gradually removing support as children become more competent.

• Zone of Proximal Development: Phase when children are receptive to learning a new skill but not yet successful at it.

Cognitive Landmarks of Early Development

• Physical reasoning: Understanding object permanence and basic physics.

• Concepts and categories: Learning to categorize objects and distinguish between types.

• Self-concept and theory of mind: Recognizing oneself and reasoning about others' beliefs.

Classic Test of Theory of Mind: False-Belief Task

• Assesses children's ability to understand that others can hold beliefs different from reality.

• Example: Child predicts where another person will look for a hidden object, even if the child knows its true location.

Developing Personality: Social and Moral Development

Stranger Anxiety

• Fear of strangers develops at 8-9 months, peaks at 12-15 months, then declines.

Temperament

• Genetic basis for social interaction styles: easy, difficult, slow-to-warm-up.

Attachment

Definition and Origins

• Strong emotional connection with significant adults.

• Attachment forms through caregiving, not imprinting (as in geese).

• Example: Study of Romanian orphanages shows importance of early emotional care.

Reactive Attachment Disorder (RAD)

• Occurs when children do not form healthy emotional bonds due to severe neglect, abuse, or unstable caregiving.

• Features: difficulty forming bonds, limited positive emotions, avoidance of social interaction, difficulty trusting others.

How Do Humans Bond?

• Contact comfort (touch) is crucial for bonding, as shown by Harry Harlow's monkey studies.

• Skin-to-skin contact is encouraged in maternity care.

Attachment Styles: The Strange Situation

Style	Description
Secure (60%)	Explores room, checks in with caregiver, greets return with joy.
Insecure-Avoidant (15-20%)	Explores independently, indifferent to caregiver, little reaction to return.
Insecure-Anxious (15-20%)	Does not explore, shows distress, mixed reactions to caregiver's return.
Disorganized (5-10%)	Inconsistent, confused responses, dazed when reunited.

Parenting Styles

Style	Definition	Example
Permissive	Lenient, few rules, lots of affection.	Parents who rarely discipline and shower children with affection.
Authoritative	Supportive, set clear and firm limits.	Parents who combine warmth with discipline and structure.
Uninvolved	Neglectful, little attention to child.	Parents who ignore children, rarely interact or discipline.
Authoritarian	Strict, little opportunity for free play, low affection.	Parents who enforce rules rigidly and punish harshly.

Parenting Styles and Later Adjustment

• Authoritative parenting linked to best social and emotional adjustment.

• Uninvolved parenting linked to worst outcomes.

• Permissive and authoritarian styles fall in between.

• Findings are correlational; genetic factors may play a role.

Social and Emotional Development in Adolescence

Bullying and Cyberbullying

• Bullying is repeated aggression by individuals with greater power or status.

• Prevalent in middle and high school; can lead to negative mental and physical health outcomes (e.g., PTSD).

• Cyberbullying more common among girls in early adolescence.

Erikson's Model of Identity Crisis

• Adolescence is a time for developing a sense of identity.

• Erikson's 8-stage model describes psychosocial crises at each stage of life.

Age	Conflict	Resolution/Virtue	Culmination
Infancy (0-1)	Trust vs. Mistrust	Hope	Appreciation of independence and relatedness
Early childhood (1-3)	Autonomy vs. Shame	Will	Acceptance of life cycle
Play age (3-6)	Initiative vs. Guilt	Purpose	Humor, empathy, resilience
School age (6-12)	Industry vs. Inferiority	Competence	Humility, acceptance of course of life
Adolescence (12-19)	Identity vs. Confusion	Fidelity	Sense of complexity of life
Early adulthood (20-25)	Intimacy vs. Isolation	Love	Sense of complexity of relationships
Adulthood (26-64)	Generativity vs. Stagnation	Care	Caritas, caring for others
Old age (65+)	Integrity vs. Despair	Wisdom	Existential identity, sense of integrity

Life Transitions in Adulthood

• Careers: Job satisfaction linked to work nature, compensation, and relationships.

• Love and Commitment: Physical and emotional intimacy associated with health and happiness.

• Parenthood: Major transition, often stressful but rewarding.

• Middle Transitions: Caring for children and aging parents ("sandwich generation").

Social Transitions in Later Years

• Life expectancy has increased; people live longer than ever.

• Depression is less common among older adults than popular myths suggest.

• Chronological age does not predict changes; consider biological, psychological, functional, and social age.