AP Psychology – Prenatal and Infant Development (Teratogens, Reflexes)

AP Psychology – Prenatal and Infant Development (Teratogens, Reflexes)

AP Psychology: Prenatal and Infant Development (Teratogens, Reflexes) – Exam-Ready Study Guide

What This Is

This topic covers how babies develop before birth (prenatal) and in their first year (infant), focusing on teratogens (harmful substances that disrupt development) and reflexes (automatic, survival-based behaviors). The AP exam tests your ability to explain how environmental factors (like alcohol or drugs) impact fetal development and how newborns’ reflexes demonstrate early brain function. Real-world example: Thalidomide, a drug prescribed in the 1950s–60s for morning sickness, caused severe birth defects (e.g., missing limbs) because it acted as a teratogen during critical periods of prenatal development.

Key Terms & Concepts

• Prenatal Development: The process of growth from conception to birth, divided into three stages:
• Germinal Stage (0–2 weeks): Zygote forms, implants in the uterus.
• Embryonic Stage (3–8 weeks): Major organs and systems develop; most vulnerable to teratogens.

• Fetal Stage (9 weeks–birth): Rapid growth, refinement of structures, and brain development.

• Teratogens: Environmental agents (e.g., drugs, viruses, chemicals) that can harm a developing fetus.

• Examples: Alcohol (FAS), nicotine, cocaine, rubella (German measles), radiation.

• Critical Period: Time when a body part is most vulnerable to damage (e.g., limbs in weeks 4–6).

• Fetal Alcohol Syndrome (FAS): A condition caused by maternal alcohol use during pregnancy, leading to physical abnormalities (e.g., facial deformities) and cognitive deficits (e.g., intellectual disability, ADHD).

• Reflexes: Automatic, unlearned responses to stimuli, present at birth and critical for survival.

• Rooting Reflex: Baby turns head toward touch on cheek (helps find food).
• Sucking Reflex: Baby sucks when roof of mouth is touched (aids feeding).
• Grasping Reflex: Baby curls fingers around an object placed in palm (precursor to voluntary grasping).
• Moro Reflex: Startle response—baby throws arms out and pulls them back when startled (may help cling to caregiver).

• Babinski Reflex: Toes fan out when sole of foot is stroked (disappears by age 2; persistence may indicate neurological issues).

• Maturation: Biological growth processes that enable orderly changes in behavior, uninfluenced by experience (e.g., walking follows a predictable sequence).

• Habituation: Decreasing responsiveness to repeated stimuli (e.g., a baby stops looking at a toy after seeing it multiple times). Used to study infant memory and perception.

• Critical Period (for development): A limited time window when exposure to certain stimuli is necessary for normal development (e.g., language acquisition in early childhood).

Step-by-Step: Analyzing Teratogen Effects on Prenatal Development

Use this process to answer FRQs or multiple-choice questions about teratogens:

1. Identify the teratogen (e.g., alcohol, nicotine, rubella).
2. Determine the stage of prenatal development (germinal, embryonic, fetal).
3. Embryonic stage = highest risk for structural damage.
4. Link the teratogen to specific effects (e.g., alcohol-FAS, nicotine-low birth weight).
5. Explain the mechanism (e.g., alcohol disrupts neural migration in the brain).
6. Consider dose and timing (e.g., heavy drinking in first trimester = worse outcomes than occasional drinking in third trimester).
7. Compare to other teratogens (e.g., cocaine vs. alcohol: cocaine restricts blood flow, alcohol damages neurons).

Example FRQ Application: "Explain how maternal alcohol use during pregnancy can lead to cognitive deficits in a child." ? Answer: Alcohol is a teratogen that crosses the placenta, disrupting neural development during the embryonic stage (when the brain forms). It causes Fetal Alcohol Syndrome (FAS), leading to microcephaly (small head/brain), neural tube defects, and impaired synaptic connections, resulting in intellectual disability, poor memory, and attention deficits.

Common Mistakes

• Mistake: Confusing maturation with learning.

• Correction: Maturation is biological growth (e.g., walking at 12 months), while learning is experience-based (e.g., riding a bike). AP loves to test this distinction!

• Mistake: Assuming all teratogens cause the same damage.

• Correction: Effects depend on timing, dose, and type of teratogen. For example:

  • Alcohol-brain damage (FAS).
  • Nicotine-low birth weight, preterm birth.
  • Rubella-deafness, heart defects.

• Mistake: Forgetting that reflexes disappear with age.

• Correction: Most newborn reflexes (e.g., Moro, Babinski) fade by 6–12 months as voluntary control develops. Persistence may signal neurological problems.

• Mistake: Overlooking habituation as a research tool.

• Correction: Habituation (e.g., a baby looking less at a repeated stimulus) proves memory and perception in infants. AP may ask how researchers use this to study cognition.

• Mistake: Ignoring cultural differences in developmental milestones.

• Correction: While maturation is universal (e.g., walking at ~12 months), experience (e.g., parenting practices) can speed up or slow down milestones (e.g., some cultures encourage earlier walking).

AP Exam Insights

1. FRQ Hot Topic: Expect a question about teratogens and their effects (e.g., "Explain how two teratogens can impact prenatal development differently"). Use specific examples (e.g., alcohol vs. cocaine) and mechanisms (e.g., neural damage vs. blood flow restriction).

2. Multiple-Choice Trap: AP loves to ask about reflexes vs. learned behaviors. For example:

3. "Which of the following is a reflex, not a learned behavior?"

   • Correct answer: Moro reflex (startle response).
   • Trap: Choosing "smiling" (which is learned later).

4. Tricky Distinction: Critical period vs. sensitive period.

5. Critical period: Necessary for development (e.g., language acquisition in early childhood).

6. Sensitive period: Optimal but not required (e.g., learning a second language is easier in childhood but possible later).

7. Experimental Design Question: AP may ask how researchers study infant perception (e.g., "How would a psychologist use habituation to study whether infants can distinguish colors?").

8. Answer: Show a baby a red square repeatedly until they habituate (look less), then show a green square. If they dishabituate (look longer), they can distinguish colors.

Quick Check Questions

1. Multiple Choice: A pregnant woman contracts rubella during her first trimester. Which of the following is the most likely outcome for her child? a) Down syndrome b) Fetal Alcohol Syndrome c) Hearing loss and heart defects d) Low birth weight due to nicotine exposure Answer: c) Hearing loss and heart defects (rubella is a teratogen that damages organs during the embryonic stage).

2. Short FRQ: "Describe two newborn reflexes and explain their adaptive value." Answer:

3. Rooting reflex: Baby turns head toward touch on cheek-helps locate food (breast/bottle).

4. Grasping reflex: Baby curls fingers around an object-may help cling to caregiver for safety.

5. Multiple Choice: Which of the following best illustrates the concept of maturation? a) A 6-month-old baby learns to crawl after watching older siblings. b) A 12-month-old baby takes their first steps without assistance. c) A 3-year-old child speaks in full sentences after attending preschool. d) A 5-year-old rides a bike after weeks of practice. Answer: b) A 12-month-old baby takes their first steps (maturation = biological growth, not learned).

Last-Minute Cram Sheet

1. Prenatal stages: Germinal (0–2 wks), Embryonic (3–8 wks, highest teratogen risk), Fetal (9 wks–birth).
2. Teratogens: Alcohol (FAS), nicotine (low birth weight), cocaine (preterm birth), rubella (deafness/heart defects).
3. FAS symptoms: Facial deformities, intellectual disability, ADHD-like symptoms.
4. Newborn reflexes: Rooting (food), sucking (feeding), Moro (startle), grasping (clinging), Babinski (toes fan).
5. Reflexes disappear by 6–12 months (persistent reflexes = neurological issue).
6. Maturation-learning (e.g., walking at 12 months = maturation; riding a bike = learning).
7. Habituation = decreased response to repeated stimuli (used to study infant memory).
8. Critical period = necessary for development (e.g., language in early childhood).
9. Not all teratogens cause the same damage (timing, dose, and type matter!).
10. Reflexes are automatic—don’t confuse them with learned behaviors (e.g., smiling is learned).