Intro to intelligence

Intelligence Tests

Definition and Characteristics

  • Intelligence Tests: Assess mental performance; not content-specific, typically comprising:
    • Broad general knowledge questions
    • Problem-solving questions
    • Given a numerical score compared to peers, often based on age
  • Typical Question Format:
    • Example question: Select the appropriate option to complete a pattern (e.g., identifying which option fits in a box).
    • Important note: Guessing correctly is acceptable without needing to explain the choice.

Origin and Historical Context

  • First Intelligence Test: Developed by Alfred Binet in France (late 1800s) with Theodore Simon as assistant.
    • Purpose: To assist school-aged children who had varying educational backgrounds; aimed to evaluate mental performance for proper educational placement.
    • Historical context:
    • Prior to law (turn of century), only wealthy children attended school due to widespread child labor; the law mandated schooling for ages 6-16, causing disparity among children's educational experiences.
    • A 10-year-old child with significant working experience entering school with only 4 years of education would struggle academically.
  • Key Terms Introduced:
    • Bright: Children with a mental age higher than chronological age.
    • Dull: Children with a mental age lower than chronological age. (Note: The term "dull" has since been associated with negative connotations).

Evolution of Intelligence Testing

  • Stanford-Binet Test (1916):
    • Created by Lewis Terman as a revision of Binet's test.
    • Purpose shifted: Initially to identify special needs children, but later used in a controversial eugenics context.
    • Eugenics Movement:
    • Belief that low intelligence was hereditary, thus linking low IQ to crime and undesirable societal traits.
    • Resulted in forced sterilization programs targeting individuals with low IQs, often without their consent—significant ethical violations.
    • Supported by a notable percentage of the population at the time (67% approval rate for sterilization programs in 1934).
  • Impact of Historical Events:
    • After WWII and the atrocities linked to Nazi policies, many sterilization practices were curtailed but persisted in some states well into the 1970s (e.g., North Carolina).
    • Additional use of the Stanford-Binet test included:
    • Immigration evaluations at points of entry (e.g., Ellis Island).
    • Assessments of World War I soldiers for mental competence.

The Genetics and Eugenics Movement

  • Driven by early 20th-century progressive ideals aiming to create a society free from violence and disease through social engineering.
  • Cold Spring Harbor Laboratory (1910): Founded by Charles B. Davenport, became central for eugenic research in the USA.
  • Prominent eugenics proponents, including biologists, argued from pseudoscientific backgrounds supporting hereditary mental traits, leading to laws for sterilization of deemed "unfit" citizens and marriage restrictions.
  • Ethical Violations and Societal Ramifications: 33 states enacted laws leading to 16,000 compulsory sterilizations.
    • Prominent case: Buck v. Bell (1927), rationalized sterilization under the guise of improving societal health.
    • Justice Oliver Wendell Holmes endorsed sterilization as a preventive measure, famously stating, "Three generations of imbeciles are enough."
  • International Inquiry into Eugenics: Notable connections between US eugenics policies and Nazi Germany, with German policies drawing inspiration from American laws.

The Intelligence Quotient (IQ) and Testing Methodologies

  • William Stern's Contribution: Refined scoring of the Stanford-Binet test using the formula:
    • IQ=(Mental Age)(Chronological Age)×100IQ = \frac{(Mental\ Age)}{(Chronological\ Age)} \times 100
  • Practice Calculations:
    • Example 1: An 8-year-old with a mental age of 10:
    • IQ=108×100=125IQ = \frac{10}{8} \times 100 = 125
    • Example 2: A 12-year-old with a mental age of 9:
    • IQ=912×100=75IQ = \frac{9}{12} \times 100 = 75
  • Problems with the IQ Formula:
    • Inapplicable for adults as gains in knowledge plateau post-college, leading to potential misinterpretation of IQ scores for individuals over their peak learning years.

Categories of Intelligence Tests

  1. Aptitude Tests: Assess potential performance in future situations (e.g., SAT, ACT).
  2. Achievement Tests: Measure knowledge acquired at present (e.g., unit tests, AP exams).

Modern Intelligence Testing

  • Current leading test: WAIS (Wechsler Adult Intelligence Scale).
    • Contains both verbal (academic question-based) and performance (problem-solving based) subtests.
    • Utilized to identify learning disabilities through discrepancies in performance across areas.

Designing Valid Intelligence Tests

  1. Standardization: Pretesting is necessary to establish an average score, indicating passing performance.
  2. Reliability: To reduce guessing effects, tests may include:
    • Split-half tests with repeated concepts asked in different ways.
    • Retesting with the same test for consistent scores.
  3. Validity: Tests must measure the targeted subject area accurately (e.g., a math test should focus solely on math concepts).

The Flynn Effect

  • Observation: Documented increase in intelligence scores over time—indicating an upward trend in average scores.
  • Debate: Raises question of whether this trend reflects natural intelligence growth or simply improved test comprehension and teaching to the test.