Intelligence & IQ Testing II - Study Notes

Intelligence & IQ Testing II - Study Notes

Lecture Details

• Course: PSY 202

• Date: January 20th

• Instructor: Dr. Avideh Gharehgazlou (Dr. G)

Neuroimaging Research Findings

• Correlation Between Brain Volume & Intelligence

  • Positive correlation identified with a correlation coefficient (CC) of 0.3-0.4.

  • Relationship appears stronger for verbal abilities compared to spatial abilities.

• Brain Activity and Intelligence

  • Higher intelligence individuals exhibit less brain activity across various brain regions while performing tasks compared to those with lower intelligence.

  • Suggests intelligence may reflect efficiency of mental processing.

  • Not universally replicated across all studies.

The Rise (& Fall) of the IQ Testing Movement

• Henry Goddard (1908)

  • Translated Binet & Simon’s IQ test into English, initiating the IQ testing movement in North America.

• Overreach of IQ Testing

  • Expansion of use from identifying children needing special education to identifying adults deemed intellectually inferior.

• Causes of Inaccurate IQ Scores

  • Language Barriers: ~40% of non-English speaking North American immigrants classified as having an intellectual disability.

  • Knowledge Deficits: Many English-speaking adults scored within the intellectual disability range due to tests originally designed for children.

The Eugenics Movement

• Origins

  • Evolved from perceptions of low IQs among immigrants.

  • Term eugenics coined by Sir Francis Galton, promoting reproductive policies aimed at enhancing genetic quality (positive eugenics) while discouraging reproduction among those labeled as inferior (negative eugenics).

• Consequences of the Eugenics Movement

  • Resulted in strict immigration restrictions from countries perceived as having low intelligence.

  • Enactment of laws allowing for forced sterilizations of individuals identified with low IQs, with Alberta being the last province in Canada to repeal these laws in 1972.

Calculating IQ

• Wilhelm Stern (1912)

  • Developed the formula for calculating IQ:
    $ext{IQ} = \frac{\text{mental age}}{\text{chronological age}} \times 100$

  • Mental Age: Age corresponding with the average performance on an intelligence test.

  • Chronological Age: Actual age in years.

• Deviation IQ

  • Adaptation of IQ calculation for adults, assessing one’s IQ relative to same-aged peers rather than using mental age.

  • Benchmark: IQ of 100 denotes average intelligence within an age group.

  • Standard Values:

  • IQ of 80 = below average

  • IQ of 120 = above average

  • Utilizes standard deviation for age norms in expressing IQ.

Stanford-Binet IQ Test

• Development

  • Modified by Lewis Terman in 1916 based on Binet & Simon’s original test.

  • Revised 5th edition currently in use, originally tailored for children now adapted for adults as well.

• Components

  • Test includes a variety of tasks mirroring those by Binet & Simon.

  • Terman's Contribution: Established normative scores in the general population for comparison.

  • Modern tests include norms stratified by age for score comparison.

WAIS

• Wechsler Adult Intelligence Scale (WAIS-IV)

  • Most widely used IQ test for adults, featuring 15 subtests.

  • Scores generated include:

  • Overall IQ

  • Verbal comprehension

  • Perceptual reasoning

  • Working memory

  • Processing speed

  • Scores compared by age utilizing established norms.

WISC & WPPSI

• Primary IQ tests for children are:

  • WISC-IV: Wechsler Intelligence Scale for Children, 4th edition.

  • WPPSI-III: Wechsler Preschool and Primary Scale of Intelligence, 3rd edition.

  • WISC-IV serves older children and adolescents, while WPPSI-III caters to younger children (ages 2.5 to 7).

Standard IQ Tests: Criticisms

• Language Dependence

  • High reliance on language may undermine performance in non-fluent test-takers.

• Cultural Bias

  • Cultural factors may impact performance when using tests not culturally tailored.

• Culture-Fair IQ Tests

  • Tests like Raven’s Progressive Matrices, designed to minimize language dependency, focusing on abstract reasoning.

Raven’s Progressive Matrices

• Overview

  • Nonverbal intelligence measurement, solving geometrical patterns in a sequential format.

  • Tasks progress in difficulty (progressive tasks) and serve as a robust measure of general intelligence (g).

Reliability of IQ Tests

• Definition

  • Reliability refers to the consistency of a measurement.

• Test-Retest Reliability

  • Refers to consistent scores upon repeated administration to the same individual.

  • High test-retest reliability noted for WAIS-IV in adulthood.

  • However, tests are unstable for ages 2 or 3; assessments for infants primarily gauge sensory abilities rather than abstract reasoning/intelligence.

Validity of IQ Tests

• Definition

  • Validity measures whether a test accurately reflects what it aims to measure.

• Concurrent Validity

  • Strong concurrent validity evident in modern IQ tests—capacity to correlate with outcomes measured simultaneously.

• Predictive Validity

  • IQ scores show strong predictive validity, relating to:

  • Academic and career success (CC: 0.5)

  • Health outcomes; negative correlations between IQ and illness likely influenced by health literacy

  • Criminal tendencies; positive correlations observed with social class.

IQ Distribution

• Bell Curve Distribution

  • Describes score distributions in which the majority cluster around the average, tapering off toward extremes (tails).

  • Research by Kari Friedrich Gass noted deviations from the perfect bell curve, particularly with an increase in low IQ scores potentially due to assortative mating.

Intellectual Disability

• Diagnosis Criteria

  • Onset must be prior to adulthood.

  • IQ must be below ~70.

  • Must demonstrate inadequate adaptive functioning.

• Categories of Intellectual Disability

  • Mild, Moderate, Severe, Profound

  • As children age and acquire functional skills, 2/3rds may no longer qualify.

Intellectual Disability - Demographics

• Mild Intellectual Disability

  • 85% of individuals diagnosed fall under this category, allowing integration into mainstream education.

  • Typically attributed to a blend of genetic and environmental influences.

• Severe Intellectual Disability

  • Less frequent familial transmission; often results from rare genetic mutations or birthing complications.

• Common Genetic Conditions

  • Fragile X Syndrome: Mutation on the X chromosome.

  • Down Syndrome: Presence of an additional chromosome 21.

Down Syndrome

• Intellectual Disability Prevalence

  • Majority present mild or moderate intellectual disability; exceptions exist within the 'mosaic' group.

• Maternal Age Correlation

  • 1 in 1,000 births affected at maternal age of 30; this increases to 1 in 12 by age 49.

Stigma & Societal Attitudes

• Evolution in societal attitudes towards individuals with intellectual disabilities noted.

• Legislative Protection:

  • Americans with Disabilities Act (ADA) and Canadian Human Rights Commission (CHRC) outlaw job and educational discrimination against disabled individuals, contributing to reduced stigma and enhanced societal inclusion.

Nature vs. Nurture: Family Studies

• Origin of Concept

  • Coined by Sir Francis Galton, family studies allow examination of trait inheritance within families.

• Findings on IQ Correlations

  • IQ is seen to “run” within families, with stronger correlations among first-degree relatives (0.5 for siblings) compared to second-degree (0.1) and third-degree relatives.

  • Galton advocates for a genetic basis of intelligence, though family studies cannot disentangle nature from nurture effects.

Nature vs. Nurture: Twin Studies

• Types of Twins

  • Monozygotic (MZ): Identical twins sharing 100% genetic material.

  • Dizygotic (DZ): Fraternal twins sharing 50% genetic material.

• Correlation in IQ

  • Higher IQ correlation in MZ twins suggests a strong genetic influence.

  • Environmental factors affect IQ similarly between MZ and DZ twins, indicating significant environmental contributions.

Nature vs. Nurture: Twin Studies Continued

• Reared Together Studies

  • MZ twins display higher IQ correlations than DZ twins when reared together, supporting genetic influence estimates between 40-70%.

  • Heritability may decrease under conditions of poverty due to environmental deprivation.

  • Change Over Time: Heritability of IQ appears to increase from childhood into adulthood.

Nature vs. Nurture: Twin Studies Continued

• Gene-Environment Interaction

  • Current research indicates intelligence involves one or a small number of genes.

  • Both Full Scale IQ (FSIQ) and Performance IQ (PIQ) are heritable; however, Verbal IQ (VIQ) shows stronger environmental explanations.

Nature vs. Nurture: Adoption Studies

• Environmental Contributions

  • Adopted children from deprived backgrounds often display IQ increases upon adoption into enriching environments.

  • Genetic similarity observed in IQs of adopted children compared to biological parents.

• Limitations

  • Selective placement can complicate findings, as children are often placed in homes similar to biological parents, which may bias results.

Environmental Influence on IQ: Education

• Correlation with Education

  • Higher educational attainment correlates with elevated IQ levels.

  • Additional schooling years result in higher IQs compared to peers.

• School Dropout Effects

  • IQ significant drops during extended absences from school, with dropouts scoring lower than continuers regardless of background.

• Early Intervention Programs

  • Can result in increased IQ, lower dropout rates, improved proficiency in literacy, and better emotional comprehension.

Environmental Influence on IQ: Poverty

• Impact of Poverty

  • Childhood adversity associated with lower IQ scores.

  • Exposure to environmental toxins correlates with intellectual deficits.

  • Unclear whether observed correlations arise from direct effects of poverty or a confluence of other factors.

Environmental Influence on IQ: Expectancy Effect

• Experimenter Expectancy Effect

  • Researchers’ biases may influence study outcomes.

• Teacher Expectations

  • Teachers may unwittingly reinforce learning in students they perceive as brighter.

  • Expectancy effects manifest when teachers have not yet formed assessments of student capabilities.

• Beliefs about Intelligence

  • Belief that intelligence is a fixed trait may deter academic risk-taking and perseverance in challenging tasks.

  • The opposing viewpoint—that intelligence can grow—encourages risk-taking and persistence.

The Flynn Effect

• Observation of Increasing IQ Scores

  • Average IQ scores have increased approximately 3 points every decade.

• Culture-Fair Tests

  • Flynn effect most noted in tests designed to minimize cultural bias.

• Modern World Effects

  • Complexity of the modern world compels adaptation at a rapid pace due to a surge in accessible information.

• Lower Tails of the Bell Curve

  • Flynn effect appears primarily to influence the lower tail of the IQ distribution.

• Home and School Changes

  • Factors contributing include increased parental time with children, improved access to resources, and extended schooling years.

  • Potentially, decreased unstructured playtime may be a contributing factor leading to the wane of the Flynn effect, which remains largely mysterious.

Sex Differences in IQ

• Female Advantages

  • Females tend to outperform males in:

  • Verbal tasks

  • Arithmetic calculations, especially basic operations (adding/subtracting)

  • Social perception and empathetic recognition, particularly in adulthood.

• Male Advantages

  • Males show strengths in tasks requiring spatial abilities, especially on mental rotation tasks and geography, with mathematics-linked reasoning differences surfacing in advanced domains (e.g., geometry) due to practice discrepancies.

Possible Causes of Sex Differences in Specific Mental Abilities

• Genetic Influences

  • Sex differences in spatial abilities have not lessened over time despite societal changes.

  • Prenatal hormonal levels have been hypothesized to play roles (excessive testosterone linked to enhanced spatial skills).

• Environmental Factors

  • Societal norms often produce minimal or non-existent sex differences in abilities, indicating environment greatly influences manifests differences.

  • Encouragement of problem-solving strategies can effectively reduce sex disparities in math performance.

Ethnic Differences in IQ

• Factor Influences

  • Ethnic differences in IQ largely attributed to socioeconomic influences rather than inherent capabilities.

  • Group IQ disparities cannot be extrapolated to infer individual capabilities, as individuals within any demographic may show significant intellectual variance.

Creativity

• Measurement of Creativity

  • Often assessed through testing regarding divergent thinking, showing aptitude for developing numerous solutions for a problem.

  • Creativity known as “outside the box” thinking exemplified by tasks such as ‘uses for objects’.

• Correlation with Intelligence

  • Intelligence and creativity are positively correlated, though distinct constructs.

Curiosity & Grit

• Variability in Traits

  • Individual differences exist in intellectual curiosity, a strong predictor of achievement beyond IQ measures.

• Definition of Grit

  • Comprises resilience and a profound passion for achieving goals.

  • Characterized by persistence through challenges and setbacks.

  • Grit is an additional predictor of success when compared to IQ.

• Distinction between Grit and Similar Traits

  • The relationship between grit and perseverance as separate from similar constructs remains a topic of investigation.

Wisdom

• Correlation with Intelligence

  • Wisdom measures exhibit moderate correlation with intelligence metrics; accruing wisdom incorporates application of intelligence for the collective good.

• Balanced Perspective

  • Wise individuals effectively reconcile personal interests with those of others and societal needs.

• Cognitive Refinement

  • Wisdom entails the appreciation of alternative viewpoints and recognition of cognitive fallibilities, aligning with adept scientific reasoning.

• Age Factor

  • Wisdom often, but not invariably, increases with age.

Can Intelligent Individuals Make Errors in Thinking?

• Odd Belief Endorsement

  • High IQ individuals may subscribe to peculiar beliefs due to their capability to articulate plausible arguments supporting those beliefs.

• Correlations with Cognition

  • IQ correlates positively with the ability to defend one’s stance yet negatively with considering alternative viewpoints.

  • Elevated IQ might intensify biases in defending against contradictory evidence.

• Confirmation Bias

  • Individuals with high intelligence may fall prey to confirmation biases while believing themselves immune to common cognitive pitfalls.