psych week 4

1. Prenatal Development

Prenatal development begins at conception and lasts until birth (about 40 weeks). It is divided into three stages: germinal, embryonic, and fetal.

2. Germinal Stage (Weeks 1–2)

  • Begins at conception when a sperm fertilizes an egg, forming a zygote.

  • The zygote undergoes rapid cell division and travels to the uterus.

  • By day 5, it becomes a blastocyst, which implants in the uterine wall around days 6–10.

3. Embryonic Stage (Weeks 3–8)

  • The blastocyst develops into an embryo and cells begin to differentiate.

  • Three germ layers form:

    • Ectoderm → Skin, nervous system (brain, spinal cord).

    • Mesoderm → Muscles, bones, circulatory system.

    • Endoderm → Digestive and respiratory systems.

  • Major Organ Systems Develop:

    • Neural tube (forms brain & spinal cord) develops by week 4.

    • Heart begins beating around week 5.

    • Limb buds appear, and facial features form.

    • Basic organ structures are in place by week 8.

4. Fetal Stage (Weeks 9–Birth)

  • Growth and refinement of organs.

  • Week 12: Reflexes develop; sex organs differentiate.

  • Week 20: Fetus moves more, can hear sounds.

  • Week 24: Viability increases (can survive if born prematurely).

  • Weeks 28–40: Rapid weight gain, brain development, lung maturation.

5. Role of Genomes & Environmental Influences

  • Genomes: DNA guides development, determining traits and organ formation.

  • Environmental Factors:

    • Cellular Neighbors: Nearby cells influence differentiation and organ formation.

    • Glial Cells: Support neurons, guide brain development.

    • Teratogens: Harmful substances (alcohol, drugs, infections) that can cause birth defects, especially in the embryonic stage.

1. Reflexes in Infancy

  • Rooting Reflex: When a baby’s cheek is touched, they turn their head and open their mouth to look for a nipple. Helps with feeding.

  • Moro Reflex: Also called the "startle reflex"; when a baby is startled, they throw out their arms and legs, then bring them back in.

2. Habituation Procedures

  • Babies become less responsive to repeated stimuli over time, showing they recognize and remember things. Used to study infant cognition.

3. Cognitive Development (Piaget’s Stages)

Sensorimotor Stage (0–2 years)

  • A-not-B error: Babies look for an object where they last saw it, not where it actually is.

  • Learn object permanence (things exist even if out of sight).

Preoperational Stage (2–7 years)

  • Egocentrism: Cannot see things from another’s perspective.

  • Failure to conserve: Don’t understand that quantity stays the same even if appearance changes (e.g., pouring water into a taller glass).

Concrete Operational Stage (7–11 years)

  • Think logically about concrete events.

  • Understand conservation and reversibility (e.g., 2+3 = 5, so 5-3 = 2).

Formal Operational Stage (12+ years)

  • Can think abstractly and use deductive reasoning.

  • Solve hypothetical problems.

4. Social Skills & Consciousness

  • Self-Concept: Awareness of self, develops around 18 months.

  • Social Comparison: By school age, children compare themselves to peers.

  • Attachment: Emotional bond with caregivers, crucial for social development.

5. Attachment Styles (Ainsworth’s Strange Situation)

  1. Secure Attachment:

    • Distressed when caregiver leaves, but easily comforted upon return.

    • Develops from responsive caregiving.

  2. Ambivalent (Resistant) Attachment:

    • Very distressed when caregiver leaves, but resists comfort.

    • Develops from inconsistent caregiving.

  3. Avoidant Attachment:

    • Little distress when caregiver leaves, avoids them upon return.

    • Develops from unresponsive caregiving.

  4. Disorganized Attachment:

    • Confusing or contradictory behavior (e.g., approaching caregiver but looking fearful).

    • Linked to neglect or trauma.

6. Nature vs. Nurture & Temperament

  • Nature (Genetics): Some infants are naturally more easygoing or difficult.

  • Nurture (Environment): Parenting style affects attachment.

  • Temperament:

    • Easy babies → More likely to form secure attachment.

    • Difficult babies → More prone to insecure attachment if caregivers struggle to meet needs.

7. Moral Development (Kohlberg’s Stages)

  1. Preconventional Morality (Before age 9)

    • Focus on punishment/reward.

    • “I won’t steal because I’ll get in trouble.”

  2. Conventional Morality (Early adolescence)

    • Focus on social rules/laws.

    • “I won’t steal because it’s against the law.”

  3. Postconventional Morality (Adolescence & beyond)

    • Focus on personal ethics and justice.

    • “I might steal if it saves a life.”

Key Point:

  • Moral reasoning ≠ Moral behavior (Knowing right from wrong doesn’t always mean acting morally).