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).