Human Development Lecture Notes
Chapter 8 Notes: Human Development Overview
Human Development: The scientific study of the changes that occur in people as they age, from conception until death.
8.1 Research Designs in Human Development
Longitudinal Design:
Definition: A design in which one participant or group of participants is studied over a long period of time.
Pros:
Looks at real age-related changes as those changes occur in the same individuals.
Cons:
Requires a lengthy amount of time, money, and effort. Participants may move away, lose interest, or die.
Cross-Sectional Design:
Definition: Several different participant groups are studied at one particular point in time.
Pros:
Quick and relatively inexpensive; easier to accomplish than longitudinal design.
Cons:
Does not track the same individuals; compares people of different ages. For instance, comparing a 30-year-old's IQ to an 80-year-old's IQ.
Cross-Sequential Design:
Definition: Participants are first studied via cross-sectional design and then followed and assessed longitudinally.
Cohort Effect:
Definition: The impact of development occurring when a group of people share a common time period or life experience.
Example: The cognitive and social changes students undergo because they were born and grew up during the age of smartphones.
8.2 Nature vs. Nurture
Nature: Refers to hereditary; the influence of inherited characteristics on personality, physical growth, intellectual growth, and social interactions.
Nurture: Refers to the influence of the environment on these characteristics, including parenting styles, physical surroundings, and economic factors.
Debate: The enduring question: Is a person like Hitler born that way, or did environmental factors contribute to who he became?
Summary: After years of research, developmental psychologists mostly agree that a combination of both hereditary and environmental influences shapes human development; however, the nature vs. nurture debate remains a hot topic.
Behavior Genetics
Behavior Genetics: Study field determining the extent to which behavior is a result of genetic inheritance versus personal experience.
Methods: Twin studies, family studies, and adoption studies.
8.3 Basic Building Blocks of Development
Genetics: The study of hereditary sciences.
DNA (Deoxyribonucleic Acid):
Definition: Special molecule that contains the genetic material of the organism.
Structure: Composed of amines and bases arranged in a specific pattern.
Function: Amines contain genetic codes for building the proteins that make up organic life.
Genes:
Definition: Sections of DNA with the same arrangement of chemical structures.
Chromosomes:
Definition: Tightly wound strands of genetic material or DNA.
Humans have 46 chromosomes in each cell (except sperm and egg); composed of 23 pairs: 23 from the mother and 23 from the father.
Autosomes: 22 pairs determine most characteristics; the last pair are sex chromosomes (XX = female, XY = male).
Gene Expressions
Dominant Gene: Controls the expression of a trait.
Recessive Gene: Influences gene expression only when paired with an identical gene.
Example: Natural blonde hair can be a trait influenced by a recessive gene.
Polygenic Inheritance: Most traits are influenced by more than one pair of genes.
Definition: When a set of genes groups together, the result can be multiple traits expressed as a single dominant trait.
Genetic and Chromosomal Disorders
Dominant Gene Disorders:
Example: Huntington's disease and Marfan syndrome; only one parent needs to pass on the gene to impact offspring.
Recessive Gene Disorders:
Disorders like Sickle Cell Anemia, Tay-Sachs Disease, Phenylketonuria, and Cystic Fibrosis require two recessive genes to be inherited.
Chromosomal Problems:
Examples: Down syndrome (extra chromosome), Turner syndrome (missing X chromosome), leading to developmental issues.
8.4 Prenatal Development
8.4 Fetalization
Ovum: Female sex cell (egg).
Sperm: Male sex cell.
Fertilization: Union of ovum and sperm.
Zygote: Result of fertilization; starts cell division (mitosis); will become an embryo.
Each cell maintains 46 chromosomes throughout division.
Types of Twins
Monozygotic Twins: Identical twins from one zygote splitting into two separate cell masses.
Dizygotic Twins: Fraternal twins from two separate eggs fertilized by different sperm, resulting in two zygotes.
Pregnancy Risks
Multiple pregnancies can be high-risk, associated with premature births and low birth weights, which can lead to disabilities.
Bioethics: Ethical questions arise regarding selective termination to enhance survival chances of remaining infants.
8.4 Stages of Development
Germinal Period: First two weeks post-fertilization; zygote implants in the uterus; placenta begins to form.
Embryonic Period: 2 to 8 weeks after fertilization; major structures develop. By end, the embryo is about 1 inch long with primitive features.
Activating structural development.
Critical Periods: Environmental influences can impact development; phases of vulnerability outlined for limb growth, heart structure, central nervous system, etc.
Prenatal Hazards (Teratogens): Any factor that causes birth defects, examples include:
Measles, mumps, rubella: Lead to defects like blindness and brain damage.
Drugs: Marijuana, Cocaine, Alcohol (Fetal Alcohol Spectrum Disorders), Nicotine, and others create specific risks.
The Fetal Period: Grow, Baby Grow
Fetal Period: From 8 weeks until birth; tremendous growth occurs.
Development of organs and functionality; growth in weight and length.
Viability increases significantly around the 24-week mark.
Miscarriages
Occur most frequently in the first 12 weeks; 12 - 20% of pregnancies end in miscarriage.
Most commonly caused by genetic defects.
Maternal Health Concerns
Nutrition: Essential vitamins and minerals.
Stress: Moderate exercise encouraged; potential harm from stress hormones.
Drugs/Illnesses: Both legal and illegal substances can pose risks to fetal development.
8.6 Infancy and Childhood Development
8.6 Physical Development Immediately After Birth
Systems functioning begins; weight loss is common in the first week.
Study infancy through preferential looking (infants prefer stimuli they like) and habituation (stop paying attention to unchanging stimuli).
Infant Reflexes
Five key reflexes essential for survival:
Grasping
Startle Reflex
Rooting Reflex
Stepping Reflex
Sucking Reflex
Motor Skills Development
Infants progress through key motor landmarks between birth and age 2:
Raising Head and Chest – 2 to 4 months.
Rolling Over – 2 to 5 months.
Sitting Up with Support – 4 to 6 months.
Sitting Up without Support – 6 to 7 months.
Crawling – 7 to 8 months.
Brain Development
Significant growth of brain neurons from birth to three years
Synaptic Pruning: Unused connections are eliminated for efficiency.
Sensory Abilities
Touch, Smell, Taste: Highly developed at birth; preference for sweet tastes established.
Hearing: Functional but requires further development.
Vision: Least functional; color perception develops over months.
8.7 Cognitive Development
Cognitive Development: Evolution of thinking, problem-solving, and memory.
Brain Weight: Triples in the first 2 years; 90% of adult weight by age 5.
Piaget’s Theory of Cognitive Development
Jean Piaget's Four Stages:
Sensorimotor (Birth - 2 Years): Knowledge through senses and motor activities; concept of object permanence developed.
Preoperational (2 - 7 Years): Ability to represent objects with words and images; limitations include egocentrism and lack of conservation.
Concrete Operations (7 - 12 Years): Logical thinking about concrete events; concrete concepts are understood.
Formal Operations (12 Years - Adulthood): Abstract reasoning; not everyone reaches this stage.
Critique of Piaget’s Theory
Some scholars argue the stages are not as distinct.
Research in non-westernized cultures supports the overall timeline, but variances exist.
Vygotsky's Theory
Emphasizes social and cultural interactions in cognitive development.
Scaffolding: Guidance provided by skilled individuals.
Zone of Proximal Development: Difference between what a child can do alone and with guidance.
Autism Spectrum Disorder (ASD)
A neurodevelopmental disorder characterized by challenges in communication and interaction; may stem from genetic and environmental factors.
8.8 Psychosocial Development
Temperament
Temperament: Behavioral characteristics established at birth which likely persist into adulthood, influenced by heredity.
Common classifications: easy, difficult, slow to warm up.
Attachment
Attachment: Emotional bond between infant and caregiver, fundamental for emotional development, formed within the first 6 months.
Attachment Styles (Mary Ainsworth - Strange Situation)
Secure: Comfort in exploring, upset by strangers but calm when caregiver is present.
Avoidant: Willing to explore but indifferent to caregiver's presence.
Ambivalent: Clingy, upset by strangers, mixed reactions upon caregiver’s return.
Disorganized-Disoriented: Confused responses; fearfulness observable.
Influences on attachment vary across cultures.
Development of Self-Concept
Self-Concept: The image one has of oneself, shaped by interactions with significant others.
Erikson’s Theory of Psychosocial Development
Development occurs through eight stages:
Trust vs Mistrust (Infancy: 0-1 year)
Autonomy vs Shame (Toddler: 1-3 years)
Initiative vs Guilt (Preschool: 3-5 years)
Industry vs Inferiority (Elementary: 5-12 years)
Identity vs Role Confusion (Adolescence: 12-20 years)
Intimacy vs Isolation (Young Adults: 20s-30s)
Generativity vs Stagnation (Middle Adulthood: 40s-50s)
Ego Integrity vs Despair (Late Adulthood: 60+ years)
Harlow’s Studies
Highlight the significance of physical contact in forming attachments in infants.