Developmental Psychology Notes: Early Deprivation, Lifespan, Research Methods, Genetics, and Prenatal Development

Romanian Orphans and Early Deprivation

  • Eleanor Ames (Nelson 2014) studied a natural opportunity: during the early 1990s, many infants in Romania were surrendered to state-run orphanages under severe deprivation. This was sparked by social policy changes, and many of these infants were later adopted internationally (e.g., by Canadian families) to escape isolation and deprivation.
  • In 1990, Ames established the Romanian Adoption Project in British Columbia to follow the progress of Romanian children adopted into Canadian families. See Bolzi & Simons (2016) for a review.
  • Condition in Romanian orphanages: infants left in cribs with minimal human contact, sometimes fed by bottles propped on pillows; little to no responsive caregiving.
  • Developmental outcomes observed after placement with families:
    • About 13\frac{1}{3} of the children fared relatively well, more likely if adopted before 14\frac{1}{4}? (text indicates before four months of age as a correlate of better outcomes; two thirds of the children who did not fare as well were adopted later).
    • All children were developmentally delayed upon arrival, but two thirds caught up to their peers’ developmental level within the first six months.
    • Some children continue to struggle with physical, behavioral, and mental health issues later in life.
  • Key takeaway: early deprivation can have lasting effects, but early adoption and enrichment can foster substantial recovery for many children.

What is Developmental Psychology?

  • Developmental psychology studies changes in behavior and mental processes over time and the factors that influence their course (constancies and changes).
  • It examines both similarities across groups and differences between individuals.
  • It is the study of changes in behavior and mental processes across the lifespan (lifespan development).
  • Lifespan perspective emphasizes how genetic, social, and historical forces influence development from conception to death.

Lifespan Development and Stages

  • Lifespan development encompasses the entire course of human life from conception to death.
  • Lifespan development programs, e.g., at the University of Victoria, study how genetic, social, and historical forces shape development.
  • Growing interest in aging has led to fields like gerontology and the psychology of aging.
  • Developmental stages (approximate ages):
    • Prenatal: conception to birth
    • Infancy and toddlerhood: birth to 2 years
    • Early childhood: 2 to 6 years
    • Middle childhood: 6 to 12 years
    • Adolescence: 12 to 20 years
    • Emerging adulthood: 20 to 25 years
    • Young adulthood: 25 to 45 years
    • Middle adulthood: 45 to 65? (text uses 45 to 60+; listed as 45–65 in some sources; here the table states 45 to 65)
    • Later adulthood: 60+ to death
  • Note: these are approximate maturational periods and are subject to variation across individuals and cultures.

Research Design in Developmental Psychology

  • Learning objective: Describe advantages and disadvantages of cross-sectional and longitudinal designs.

Cross-Sectional Design

  • Definition: Compare groups of people of different ages at a single point in time.
  • Example: Compare memory performance of a group of 60-year-olds with a group of 30-year-olds right now.
  • Advantages:
    • Quick and easy to administer; convenient for researchers and participants.
    • Provides information about age differences.
  • Disadvantages:
    • Cohort effects: differences may reflect historical and cultural experiences of a cohort rather than development per se.
    • Example: 30-year-olds may be more computer-lamiliar than 60-year-olds; this could confound age effects with cohort effects.
    • Does not explain how or when changes occurred; measures at a single point in time.
    • If memory tasks show older adults perform differently, it’s unclear if the difference is due to aging or cohort factors.
  • Cohort effect: any group of people born at about the same time exposed to similar cultural/historical experiences.
  • Illustrative Alberta example: funding cuts to kindergarten hours could produce cohort differences in grade medical? No; used to illustrate how cohort effects can confound conclusions about development.

Longitudinal Design

  • Definition: Follow the same group of people over a period of time, administering the same tasks or questionnaires at multiple points.
  • Example trajectory: Start with participants at age 2020, retest at later ages (e.g., 4040, then 6060) to observe changes within the same individuals.
  • Advantages:
    • Changes over time can be attributed more confidently to development rather than cohort differences.
    • Yields information about stability/instability of traits and the effects of early experiences.
  • Disadvantages:
    • Time-consuming and expensive.
    • Participant attrition: people drop out due to relocation, loss of interest, illness, or death.
    • Still susceptible to cohort effects if the sample is drawn from a single cohort.

Cohort Sequential Design

  • Definition: A blended design combining cross-sectional and longitudinal approaches; two or more longitudinal studies starting with different age groups.
  • Purpose: Separate age effects from cohort effects by overlapping age ranges across cohorts.
  • Example: Substance abuse prevalence among Indigenous adolescents in the US and Canada followed over eight years with staggered cohorts (e.g., starting around ages 11.3, then adding new cohorts at later times).
  • Advantages:
    • Can separate cohort effects from age effects; provides reliable information about age changes and early experiences.
    • Addresses some limitations of purely cross-sectional and purely longitudinal designs.
  • Disadvantages:
    • Requires substantial time and resources; complex to analyze.

Practical Studies and Programs Mentioned

  • Aboriginal Head Start on Reserve (AHSOR): half-day preschool on reserves for Indigenous and Métis children (ages 2–5). Emphasizes family engagement and cultural/language education; includes health promotion, nutrition, and social supports.
  • Aboriginal Head Start in Urban and Northern Communities (AHSUNC): for Indigenous families living off reserve in urban/northern communities. Focuses on engaging families to support parenting, reduce isolation, and connect families with Indigenous identity/heritage.
  • Evaluation findings (AHSOR): children performed at or above age peers when entering school, suggesting program effectiveness; longitudinal follow-up is needed to determine long-term impacts on dropout rates.
  • Evaluation findings (AHSUNC): coordinators/workers stressed supportive, nonjudgmental relationships with families; increased parental self-esteem, self-efficacy, and involvement; connections to other families and elders helped reduce social isolation; linking families to Indigenous identity and heritage was important.
  • Implication: engaging families and communities can bolster development in Indigenous contexts and more broadly in contexts of adversity.

Integration Across Designs

  • Some researchers combine cross-sectional and longitudinal approaches (cohort sequential) to capitalize on the strengths of each while mitigating their weaknesses.

Nature, Nurture, and Epigenetics

  • Big debates in development:
    • Nature (genetics) vs. nurture (environment)
    • Maturation: biologically programmed sequence of development
    • Epigenetics: environmental inputs can cause changes in gene expression without changing the DNA sequence; these epigenetic changes can be temporary or permanent and may be heritable across generations.
  • Interaction: Most traits result from an interaction between genes and environment; it is not easy to attribute development solely to nature or nurture.
  • Epigenetic memory: environmental experiences can create chemical marks that influence gene expression; these can act as a memory that shapes development.

Stages vs Continuity: Qualitative vs Quantitative Change

  • Stage concept: development involves distinct phases where thinking/behavior changes qualitatively (e.g., Piaget’s stages of cognitive development).
  • Quantitative change: gradual increases in size, strength, measurement (height, weight, reaction time).
  • Debate: some researchers emphasize qualitative stage-like changes; others argue ongoing quantitative accumulation can explain development.
  • Most researchers view development as involving both qualitative and quantitative processes.
  • Example illustration: walking may result from gradual quantitative changes in muscle strength and neural control, culminating in coordinated gait.

Critical Periods and Sensitive Periods

  • Critical period: a time window during which an organism is especially sensitive to environmental input; missing input can lead to permanent deficits.
  • Lorenz imprinting (geese): geese imprint on a moving stimulus (e.g., boots) within ~36 hours after hatching, demonstrating a critical period for attachment formation.
  • Human critical periods: evidence is more limited and ethically constrained; deprivation studies show serious impacts but also potential for partial recovery with environmental changes.
  • Sensitive period: modern view that periods are especially receptive to input but not rigidly bound; more flexible and influenced by experience.
  • Visual system studies: early visual input is necessary for face recognition; bilateral congenital cataracts highlight the importance of early input, with long-term effects if deprived, but not absolute irreversibility.

Nature–Nurture and Prenatal Development: Genetics and Inheritance

  • Prenatal period: from conception to birth; three stages:
    • Germinal (conception to ~2 weeks): zygote forms and divides; placenta forms; implantation occurs; zygote becomes blastocyst; placenta facilitates oxygen/nutrient exchange via the umbilical cord.
    • Embryonic (2–8 weeks): major organ systems begin to form; high vulnerability to environmental influences.
    • Fetal (end of 8 weeks to birth): organ systems mature; brain growth accelerates in last trimester.
  • Key terms:
    • Zygote: a single cell formed by fertilization of the egg by sperm.
    • Placenta: nutrient-rich structure that connects to the uterus and allows exchange of nutrients and oxygen with the fetus.
    • Implantation: attachment of the blastocyst to the uterine wall.
  • Genetic fundamentals:
    • 23 pairs of chromosomes; total of 46 chromosomes; one chromosome from each parent per pair.
    • Genes: basic units of genetic inheritance encoded in DNA.
    • Genotype: an individual’s genetic makeup.
    • Phenotype: observable traits (physical and behavioral).
    • Alleles: different forms of a gene.
    • Dominant vs Recessive:
    • Dominant trait: expressed in the phenotype if at least one dominant allele is present (e.g., freckles from a dominant allele).
    • Recessive trait: expressed only if two recessive alleles are present (homozygous recessive).
    • Homozygous: two identical alleles for a trait.
    • Heterozygous: two different alleles for a trait.
    • Codominance: heterozygous individuals display both alleles in the phenotype (e.g., AB blood type from A and B alleles).
    • Polygenic traits: traits influenced by many genes (e.g., height, skin color, intelligence; behavior is often polygenic).
  • Examples of genetic disorders and concepts:
    • Down syndrome (trisomy 21): a chromosomal abnormality involving an extra copy of chromosome 21.
    • Sickle cell anemia, cystic fibrosis, phenylketonuria (PKU): recessive-gene disorders.
    • Marfan syndrome, Huntington’s disease: dominant-gene disorders.
    • Many disorders arise from chromosomal problems beyond simple inheritance.
  • Environment and gene interaction: environment can influence expression of genetic traits; not all traits are purely genetic or purely environmental.
  • Teratogens (environmental agents that cause damage during gestation):
    • Effects depend on dose, timing, duration, and developmental stage (zygote → embryo → fetus).
    • Not all teratogens produce immediate defects; some effects appear later in childhood or adulthood.
    • Examples and effects:
    • Rubella (three-day measles): prenatal exposure can cause deafness, intellectual disability, and organ defects in embryonic period.
    • Other infections: syphilis, genital herpes, AIDS, Zika virus (public health emergency by WHO).
    • Marijuana (prenatal exposure): linked to disturbances in executive function (impulsivity, hyperactivity, inattention) and later maternal depression.
    • Tobacco: miscarriage risk, low birth weight, cleft lip/palate, prematurity; postnatal risks include SIDS, asthma, cancer risk later in childhood.
    • Alcohol: prenatal exposure disrupts neuron production and neuronal migration; can cause fetal alcohol spectrum disorders (FASD).
      • FASD is a broad category including FAS (fetal alcohol syndrome), partial FAS (PFAS), and alcohol-related neurodevelopmental disorder (ARND).
      • FAS features: characteristic facial features, growth retardation, brain injury.
      • Estimated prevalence in Canada has varied; some studies suggest 2–3% in Ontario schoolchildren; 3–4 thousand affected births per year in Canada (estimates vary).
  • Important prenatal statistics from the transcript:
    • Miscarriage: about 14\frac{1}{4} of conceptions end in miscarriage during the first eight weeks.
    • Among women who know they are pregnant, about 16\frac{1}{6} experience a miscarriage.
    • Preterm and small-for-date births are influenced by maternal stress, poor weight gain, and short stature in the mother.
    • Viability age (from the transcript): point at which a baby can survive on its own; preterm defined as delivered before 3030 weeks gestation in the notes; small-for-date defined as birth weight $$ ext{≤ }$-10 ext{%}$ below the mean for gestational age.
  • Summary: development results from complex interactions among genes, environment, and timing; prenatal development is a highly sensitive period where teratogens can have profound effects depending on exposure characteristics; ethical constraints limit experimentation, so naturalistic observations (e.g., deprivation studies, adoption outcomes) and observational designs are essential for understanding development.

Questions to Consider (Review Prompts from the Transcript)

  • What are the possible phenotypic outcomes from a heterozygous genotype for a given trait (dominant vs recessive vs codominant patterns)?
  • What are teratogens, and on what factors do their effects depend (dose, timing, exposure duration, developmental stage)?
  • What are the three stages of prenatal development, and what happens at each stage? What are the potential prenatal risks associated with each stage?
  • What evidence supports the idea that both biology and environment shape development? How do epigenetic mechanisms contribute to this interplay?
  • In light of the Romanian orphan studies, how do early experiences influence later development, and what factors contribute to recovery or persistent difficulties?
  • How do cross-sectional, longitudinal, and cohort sequential designs each contribute to our understanding of developmental change? What are their strengths and limitations?
  • How do the Aboriginal Head Start programs (AHSOR and AHSUNC) illustrate the role of family engagement and cultural context in child development?
  • What is the difference between a critical period and a sensitive period, and what evidence supports each view?