Developing Through the Life Span Vocabulary
Overview of Human Developmental Psychology
Human Development: Defined as the scientific study of changes in people from conception until death.
Captures physical, cognitive, social, and moral development across the entire human life span.
Developmental Research Designs
Longitudinal Study:
A research design in which the same individual or group of participants is followed and retested repeatedly over an extended period of time (e.g., assessing an individual across multiple years such as 1994, 2002, and 2014).
Tracks developmental trajectory across cognitive, social, moral, and physical domains in the same cohort.
Advantages: Directly measures age-related changes within individuals; controls for cohort effects.
Disadvantages: Time-consuming, expensive, and susceptible to participant attrition (drop-out over time).
Cross-Sectional Study:
A research design in which groups of participants of different ages (e.g., Group 1, Group 2, Group 3) are evaluated and compared at a single point in time (e.g., all tested in 2014).
Assesses age-related differences across cognitive, social, moral, and physical domains simultaneously.
Advantages: Fast, efficient, and cost-effective; eliminates participant attrition risks.
Disadvantages: Susceptible to cohort effects (differences resulting from historical, cultural, or environmental factors unique to specific birth years rather than true developmental aging).
Nature Versus Nurture Interaction
Developmental psychologists broadly agree that human development is the product of an ongoing, interactive relationship between nature (genetic/biological heritage) and nurture (environmental experience and context).
Prenatal Development and Conception
Conception:
Occurs when a single sperm cell (male) penetrates the outer protective coating of the egg/ovum (female) and fuses with it to form one fertilized cell (a zygote).
Germinal Period:
Duration: Conception to approximately 2 weeks.
Begins with the formation of the zygote (fertilized cell).
Cells multiply rapidly and become increasingly specialized and diverse through cell division and differentiation.
At approximately 14 days post-conception, the blastocyst implants into the uterine wall and transitions into an embryo.
Embryonic Period:
Duration: Week 2 through Week 8.
Critical structural development occurs, establishing the foundations of major organ systems, the central nervous system, and physical anatomy.
Fetal Period:
Duration: Week 9 through birth (approximately 38–40 weeks).
At 9 weeks post-conception, the embryo officially becomes a fetus.
Characterized by rapid body growth, organ system maturation, and structural refinement (e.g., distinct human features observable at 4 months).
Sensitive Periods and Teratogens
Sensitive / Critical Periods in Pregnancy:
Specific periods during gestation when embryonic or fetal tissues are maximally vulnerable to structural or functional disruption from environmental influences.
Major structural defects occur predominantly during the embryonic period (weeks 3–8), whereas minor structural and functional defects occur during the fetal period (weeks 9–38).
Vulnerability timeline by system:
Central Nervous System (Brain/Spinal Cord): High vulnerability to major structural defects from weeks 3 through 16; functional/minor defect sensitivity extends through week 38.
Heart: Highly sensitive from weeks 3 to 6; functional/minor sensitivity extends to week 8.
Arms and Legs: Highly sensitive from weeks 4 to 7; minor sensitivity extends to week 8.
Eyes: Highly sensitive from weeks 4 to 8; functional/minor sensitivity extends to week 38.
Ears: Highly sensitive from weeks 4 to 9; minor sensitivity extends to week 20.
Teeth: Highly sensitive from weeks 6 to 8; minor sensitivity extends to week 38.
Palate: Highly sensitive from weeks 6 to 8; minor sensitivity extends to week 12.
External Genitals: Highly sensitive from weeks 7 to 8; functional/minor sensitivity extends to week 38.
Teratogens:
Any environmental agent (biological, chemical, or physical) that can cause birth defects or developmental malformations in a developing embryo or fetus.
Thalidomide: Historically prescribed drug causing severe limb reduction defects.
Nicotine: Associated with miscarriage, low birth weight, stillbirth, short stature, intellectual disability, and learning disabilities.
Alcohol: Causes Fetal Alcohol Syndrome (FAS), resulting in intellectual disability, delayed growth, facial malformation, learning difficulties, and abnormally small head size (microcephaly).
Physical facial signs of FAS: Small head, low nasal bridge, epicanthal folds, small eye openings, flat midface, short nose, smooth philtrum, thin upper lip, and underdeveloped jaw.
Additional Teratogenic Agents:
Measles, Mumps, and Rubella: Blindness, deafness, heart defects, brain damage.
Marijuana: Irritability, nervousness, tremors; infant is easily disturbed and startled.
Cocaine: Decreased height, low birth weight, respiratory problems, seizures, learning difficulties; infant is difficult to soothe.
Mercury: Intellectual disability, blindness.
Vitamin A (high doses): Facial, ear, central nervous system, and heart defects.
Caffeine: Miscarriage, low birth weight.
Toxoplasmosis: Brain swelling, spinal abnormalities, deafness, blindness, intellectual disability.
High Water Temperatures: Increased chance of neural tube defects.
Nutritional Deficiencies:
Maternal folic acid deficiency during early pregnancy directly increases the risk of neural tube defects (such as spina bifida and anencephaly).
Newborn Physical Development and Survival Reflexes
Five Reflexes for Survival:
Stepping Reflex: Automatic stepping movements when held upright with feet touching a flat surface.
Grasping Reflex: Involuntary curling of fingers around an object placed in the infant's palm.
Moro (Startle) Reflex: Arching of the back, throwing back of the head, and flinging out of arms and legs in response to a sudden noise or loss of support.
Sucking Reflex: Automatic rhythmic sucking response triggered by touching the roof of the infant's mouth.
Rooting Reflex: Turning of the head and opening of the mouth toward a light touch on the cheek.
Development of the Visual System
Prenatal Visual Development: Basic light responsiveness develops in utero.
Achromatic Vision at Birth: Newborn vision is strictly black-and-white (achromatic) because color-detecting photoreceptor cells (cones) are immature.
Photoreceptor Maturation:
Rod photoreceptor cells finish maturing during the last 3 to 4 months of gestation.
Cone photoreceptor cells mature approximately 3 months post-birth, allowing full color vision to emerge.
Visual Acuity: Newborn visual acuity is approximately (objects at 20 feet appear as blurry as they would to an adult with vision). Visual acuity sharpens progressively over the first year ().
Neurodevelopment and Environmental Experience
Processes in Infancy and Childhood Brain Maturation:
Myelination: Coating of neural axons with myelin sheaths to increase electrical impulse speed.
Synaptic Pruning: Elimination of unused neural connections to optimize brain processing efficiency.
Critical or Sensitive Periods: Windows of elevated neuroplasticity during which environment-driven experiences shape neural wiring.
Enriched vs. Impoverished Environments (Mark Rosenzweig Study):
Raising laboratory animals in enriched environments (with play structures, novelty, and social companions) produces significantly heavier cerebral cortices and more elaborate, complex dendritic branching compared to raising animals in isolated, impoverished cages.
Infant Cognitive Capabilities
Innate Preferences:
Newborns demonstrate automatic perceptual preferences for human faces, novel objects, and moving stimuli.
Habituation:
Process by which infants display decreased responding to a stimulus after repeated exposure.
Researchers utilize habituation paradigms to test infant stimulus discrimination and memory.
Infant Memory (Rovee-Collier Mobile Experiment):
Demonstrated explicit memory retention in 3-month-old infants.
Procedure: A ribbon is connected from a 3-month-old infant's ankle to an overhead crib mobile. The infant rapidly learns that kicking causes the mobile to move.
Result: Re-tested days later without the ribbon attached, infants immediately kick their leg, proving memory retention of the contingency.
Intuitive Physics and Mathematics:
Infants possess innate expectations regarding physical laws and object properties.
Infants use object motion to infer that objects moving together form a continuous single entity.
Violation of Expectation Method:
Infants look significantly longer at physically impossible events than possible events.
Example: In physics experiments, infants view a possible event (a box placed on top of another box stays supported) versus an impossible event (a box released in midair remains floating). Infants stare longer at the midair suspended box, proving an intuitive concept of gravity.
Piaget's Stage Theory of Cognitive Development
Core Cognitive Concepts:
Schemas: Mental frameworks that categorize and organize information.
Assimilation: Fitting new information into existing mental schemas without altering the schema.
Accommodation: Modifying existing schemas or creating new ones when new information contradicts existing frameworks.
Stage 1: Sensorimotor Stage (Birth – 2 Years):
Infants experience the world through sensory impressions and motor activities.
Object Permanence: The understanding that objects continue to exist when out of sight (develops around 8 months).
A-not-B Error: Tendency of infants to search for a hidden object in Location A (where previously found) even after witnessing it moved to Location B.
Stage 2: Preoperational Stage (2 – 7 Years):
Children represent concepts with words and images but lack logical mental operations.
Egocentrism: Inability to perceive physical or conceptual viewpoints other than one's own.
Conservation Deficits: Inability to recognize that physical mass, volume, or quantity remains unchanged despite altered appearance. Caused by:
Centration: Focusing on only one feature of an object or situation while ignoring others.
Irreversibility: Inability to mentally reverse an action or transformation.
Theory of Mind: Ability to infer others' mental states, feelings, and beliefs. Impairment in Theory of Mind is a hallmark feature of Autism Spectrum Disorder (ASD).
Conservation Tasks:
Liquids: Pouring equal liquid into a taller, narrower glass. Preoperational answer: Taller glass has more.
Number: Spacing out an identical row of pennies. Preoperational answer: Longer row has more.
Stage 3: Concrete Operations Stage (7 – 12 Years):
Children gain logical thinking abilities applied to concrete, tangible objects and events.
Accomplishments: Mastery of Conservation via Decentration (considering multiple dimensions) and Reversibility; ability to perform Classification and apply Concrete Logic.
Stage 4: Formal Operations Stage (12 Years – Adulthood):
Development of abstract, systematic, and hypothetical thinking.
Accomplishments: Ability to process Abstractions and Analogies; systematic Hypothesis Testing ("What if…" reasoning).
Infant Temperament
Definition: Biological, genetically based emotional and behavioral reactivity established at birth.
Temperament Patterns:
Easy: Cheerful, relaxed, easily adapts to new experiences, establishes predictable eating/sleeping routines.
Difficult: Irritable, intense emotional reactions, unpredictable routines, slow to accept new experiences.
Slow to Warm Up: Low activity level, somewhat negative, cautious, but slowly adapts with repeated exposure.
Attachment and Psychosocial Development
Ainsworth's "Strange Situation":
Observational procedure assessing infant-caregiver attachment styles through series of caregiver departures and returns in an unfamiliar room.
Attachment Classifications:
Secure Infants: Explores freely using caregiver as a base; distressed during separation; seeks contact and is easily comforted upon reunion.
Avoidant Infants: Shows little distress during separation; avoids or ignores caregiver upon reunion.
Ambivalent (Resistant) Infants: Deeply distressed during separation; seeks contact upon return but exhibits anger and cannot be comforted.
Disorganized-Disoriented Infants: Shows confused, contradictory, or fearful behaviors during reunion; often linked to abusive or neglectful caregiving.
Erikson's Stages of Psychosocial Development
8 Life Stages and Central Crises:
Trust vs. Mistrust (Stage 1, Infancy): Developing trust when physical and emotional needs are consistently met.
Autonomy vs. Shame and Doubt (Stage 2, Toddlerhood): Developing self-control and independence.
Initiative vs. Guilt (Stage 3, Preschool): Learning to initiate tasks and carry out plans.
Industry vs. Inferiority (Stage 4, Elementary School): Applying self to learning skills and feeling competent.
Identity vs. Role Confusion (Stage 5, Adolescence): Testing roles and integrating them to form a cohesive self-identity.
Intimacy vs. Isolation (Stage 6, Early Adulthood): Forming close, committed personal relationships.
Generativity vs. Stagnation (Stage 7, Middle Adulthood): Contributing to family, work, and future generations.
Ego Integrity vs. Despair (Stage 8, Late Adulthood): Reflecting on life with acceptance, sense of completeness, and satisfaction.
Adolescence
Adolescence: Transition stage between childhood and adulthood (ages 13 to early 20s).
Physical & Cognitive Features:
Puberty: Biological sexual maturation; development of secondary sex characteristics.
Adolescent Egocentrism: Self-absorbed focus involving imaginary audience beliefs and personal fable assumptions.
Brain Maturation Asymmetry:
The limbic system (drives emotion, motivation, and reward) matures faster than the prefrontal cortex (drives executive control, planning, impulse restraint, and long-term judgment).
Leads to heightened risk-taking behaviors and emotional reactivity.
Legal Impact: Evidence of incomplete prefrontal cortex maturation contributed to legal precedent prohibiting the death penalty for juvenile crimes due to diminished culpability and impaired impulse control.
Development of Morality (Piaget and Lawrence Kohlberg):
Proposed that cognitive moral reasoning directly directs moral actions.
Examined via ethical dilemmas (such as the Trolley Problem).
Kohlberg's Levels of Moral Thinking:
Preconventional Morality (Before age 9):
Focus: Self-interest; rules obeyed to avoid punishment or earn rewards.
Example: "If you steal the medicine, you will go to jail."
Conventional Morality (Early adolescence):
Focus: Upholding laws and social rules to gain social approval or maintain social order.
Example: "If you steal the medicine, everyone will think you're a criminal."
Postconventional Morality (Adolescence and beyond):
Focus: Actions driven by belief in human rights and self-defined universal ethical principles.
Example: "People's right to live matters more than property or profits."
Adulthood and Aging
Adulthood: Begins in early 20s; divided into young adulthood, middle adulthood, and late adulthood.
Psychosocial Tasks across Adulthood:
Young Adulthood (Stage 6: Intimacy vs. Isolation): Establishing deep, committed relationships without losing individual identity.
Middle Adulthood (Stage 7: Generativity vs. Stagnation): Directing creativity and productivity toward nurturing the next generation.
Late Adulthood (Stage 8: Ego Integrity vs. Despair): Achieving wisdom, tranquility, and wholeness of self through reflection and life acceptance.