PRINCIPLES OF DEVELOPMENT: Development follows predictable, universal patterns: (1) CEPHALOCAUDAL — development proceeds from HEAD to TOE. Infants gain head control before sitting, sitting before standing, standing before walking. (2) PROXIMODISTAL — development proceeds from CENTRE to PERIPHERY. Trunk control develops before arm control, arm before hand, hand before finger dexterity. (3) GENERAL TO SPECIFIC — gross motor before fine motor (random arm waving before precise grasping). (4) CONTINUOUS AND GRADUAL — development is not sudden; it builds on prior stages. (5) INDIVIDUAL DIFFERENCES — every child develops at their own pace within the normal range. (6) DEVELOPMENT IS BOTH QUANTITATIVE AND QUALITATIVE — height/weight (quantitative) AND cognitive ability/reasoning (qualitative) both develop. (7) DEVELOPMENT IS PREDICTABLE — milestones follow a set sequence even if timing varies. (8) HEREDITY AND ENVIRONMENT INTERACT — neither alone determines development (nature vs nurture debate resolved as INTERACTION).

PRENATAL DEVELOPMENT: Three periods: (a) GERMINAL (0-2 weeks) — fertilization, zygote formation, implantation. (b) EMBRYONIC (2-8 weeks) — major organs begin forming, most vulnerable to teratogens (harmful substances). Heartbeat begins. (c) FETAL (8 weeks-birth) — rapid growth, organ maturation, movement. Development sequence within fetus (Q.148 DHD68): Heartbeat begins → Tactile response in oral-nasal region → Arm/leg/trunk movement → Grasp and Babinski reflexes. INFANT REFLEXES (present at birth, disappear as nervous system matures — their disappearance is a SIGN OF NORMAL DEVELOPMENT): Rooting (turns head toward touch on cheek, 3-6 months), Moro/Startle (arms fling out when startled, 3-4 months), Grasp/Palmer (grips object placed in palm, 6-7 months), Babinski (toes fan out when sole is stroked, 8-12 months), Sucking (sucks objects placed in mouth). If reflexes PERSIST beyond expected age → sign of neurological concern.

STAGES OF DEVELOPMENT: (a) INFANCY (Birth-2 years): Rapid physical growth. Motor milestones: head control (2-3 months) → rolling (4-6 months) → sitting (6-8 months) → crawling (8-10 months) → walking (12-15 months). Attachment forms (Bowlby). Piaget's sensorimotor stage. Object permanence develops (~8 months). (b) EARLY CHILDHOOD (2-6 years): Language explosion. Piaget's preoperational stage (symbolic thinking, egocentrism, animism, centration). Parallel play → cooperative play. Kohlberg's preconventional morality. Initiative vs Guilt (Erikson). (c) MIDDLE CHILDHOOD (6-11 years): School years. Piaget's concrete operational stage (conservation, classification, seriation). Peer relationships become important. Industry vs Inferiority (Erikson). (d) ADOLESCENCE (11-18 years): Puberty. Piaget's formal operational stage (abstract thinking, hypothetical reasoning). Identity vs Role Confusion (Erikson). Kohlberg's conventional morality. Storm and Stress theory (G. Stanley Hall).

EMOTIONAL DEVELOPMENT: Emotions develop in a sequence (Bridge, 1932): EXCITEMENT (birth, only emotion) → DELIGHT + DISTRESS (3 months) → Delight branches into: AFFECTION (6 months), ELATION (12 months), JOY (24 months). Distress branches into: ANGER (6 months), DISGUST (18 months), FEAR (12 months), JEALOUSY (18+ months). CRYING is the infant's FIRST medium of communication — triggered by hunger, pain, temperature change, noise. By 2-3 months, different cry patterns emerge for different needs. SOCIAL SMILE appears around 6-8 weeks. STRANGER ANXIETY develops around 8-12 months. SEPARATION ANXIETY peaks at 12-18 months.

INTELLIGENCE AND IQ: IQ FORMULA (William Stern): IQ = (Mental Age / Chronological Age) × 100. Example: A 10-year-old with mental age 12 → IQ = (12/10) × 100 = 120. IQ CLASSIFICATION: Below 25 = Profound intellectual disability, 25-39 = Severe, 40-54 = Moderate, 55-69 = Mild, 70-79 = Borderline, 80-89 = Low Average, 90-109 = Average, 110-119 = High Average, 120-139 = Superior, 140+ = Genius/Very Superior. INTELLECTUAL DISABILITY levels in increasing difficulty (REET Q.79 PQR): Mild (IQ 55-70) → Moderate (IQ 35-55) → Severe (IQ 20-35) → Profound (IQ below 20). INTRAINDIVIDUAL DIFFERENCE (Q.149 DHD68): When the SAME person shows different levels across domains (e.g., high intelligence but low social skills). INTERINDIVIDUAL DIFFERENCE: differences BETWEEN two or more people.

KOHLBERG'S MORAL DEVELOPMENT: Three levels, each with two stages: PRECONVENTIONAL LEVEL (childhood): Stage 1 — Obedience/Punishment orientation (right = avoiding punishment). Stage 2 — Instrumental purpose (right = self-interest, reciprocity). CONVENTIONAL LEVEL (adolescence-adult): Stage 3 — Good boy/Nice girl (right = gaining approval). Stage 4 — Law and Order (right = following rules, maintaining social order). POSTCONVENTIONAL LEVEL (adult, not everyone reaches): Stage 5 — Social Contract (right = democratic agreement, individual rights). Stage 6 — Universal Ethical Principles (right = self-chosen ethical principles, even if they conflict with law). CRITICISM: Kohlberg's research was primarily on MALES (Carol Gilligan criticized this — she proposed an 'Ethics of Care' alternative for women's moral reasoning). Stages may not be universal across cultures.

ERIKSON'S PSYCHOSOCIAL STAGES (8 stages across entire lifespan): (1) Trust vs Mistrust (0-1 year, infant). (2) Autonomy vs Shame & Doubt (1-3 years, toddler). (3) Initiative vs Guilt (3-6 years, early childhood). (4) Industry vs Inferiority (6-12 years, school age — most relevant for REET). (5) Identity vs Role Confusion (12-18, adolescence). (6) Intimacy vs Isolation (young adult). (7) Generativity vs Stagnation (middle adult). (8) Integrity vs Despair (old age). KEY DIFFERENCES FROM FREUD: Erikson = PSYCHOSOCIAL (social interactions shape personality). Freud = PSYCHOSEXUAL (biological drives shape personality). Erikson covers ENTIRE lifespan; Freud focuses on childhood. Both are stage theorists but with very different mechanisms.

REET EXAM TIPS (15+ questions — one of the top 3 topics): (1) Development principles: cephalocaudal=head to toe, proximodistal=centre to periphery. (2) IQ formula and classification — calculate actual IQ from given MA and CA. (3) Intellectual disability ORDER: Mild→Moderate→Severe→Profound. (4) Kohlberg's 6 stages in 3 levels. (5) Erikson's 8 stages matched to age ranges. (6) Emotional development sequence: Excitement→Delight→Affection→Joy. (7) Intra vs Inter individual differences. TRAPS: 'Proximodistal means head to toe' — FALSE (that's cephalocaudal). 'IQ below 80 is intellectual disability' — FALSE (below 70). 'Kohlberg's stages apply equally to men and women' — CONTESTED (Gilligan's critique). 'Erikson's stages are psychosexual' — FALSE (psychosocial; Freud is psychosexual). 'Genetic material is called phenotype' — FALSE (it's GENOTYPE; phenotype is observable characteristics).