Intelligence Measurement: Approaches and Testing

• Intelligence testing is a way to measure mental capabilities using standardized tests.
• Graduate Records Examination (GRE), Law School Admissions Test (LSAT), and Medical College Admissions Test (MCAT) are examples of intelligence tests.

The Anthropometric Approach

• Sir Francis Galton (1822-1911) studied intelligence using anthropometrics.
• Anthropometrics is a historical term for measuring physical and mental variation in humans.
• Sensory abilities were measured as an indicator of intelligence.
• Social Darwinism was part of this approach.

The Binet-Simon Approach

• Alfred Binet (1857-1911) and Theodore Simon (1872-1961) defined intelligence as the ability to think, understand, reason, and adapt.
• Mental age refers to the average intellectual ability score for children of a specific age.
• Current ability is relative to age, but changeable.

Stanford-Binet Test

• Lewis Terman (1877-1956) developed a test to measure innate (genetic) intelligence.
• It incorporates the Intelligence Quotient (IQ).
• IQ is calculated as (Mental Age / Chronological Age) * 100.
• For example, a 7-year-old with a mental age of 7 and a chronological age of 10 will have an IQ of 70.
• This test set the stage for misguided uses of intelligence tests.

Sample Calculation

• Early intelligence tests assumed intelligence continually increased.
• Intelligence scores stabilize around the age of 16.

The Wechsler Adult Intelligence Scale (WAIS)

• The WAIS test is commonly used to measure intelligence in adolescents and adults.
• Deviation IQ compares a person's IQ with the average score for their age group.

Distribution of Scores

• Standardized intelligence scores show a normal distribution.

Breaking IQ Up

• General ability index measures the ability to solve problems
• Cognitive proficiency index measures how quickly someone can solve problems
• Verbal comprehension index measures verbal skills.
• Perceptual reasoning index measures non-verbal reasoning.
• Working memory index assesses short-term memory and attention.
• Perceptual speed index assesses the ability to quickly process visual information.

Raven's Progressive Matrices

• Raven's Progressive Matrices is an intelligence test that emphasizes problems that are not bound to a specific language or culture.
• Scores correlate with WAIS.

A Troubling Past

• IQ testing has been linked to eugenics and sexual sterilization acts (1928-1972).
• Racial differences in IQ persist, even when using Raven's matrices.

"The Bell Curve"

• Society consists of cognitive elites and those with lower IQs should not receive assistance from social programs.

Race as a Concept

• Race is a social construct, not a biological one.
• Social conceptions of race have evolved based on 'folk taxonomies'.

Problems With The Racial Superiority Interpretation

• Culturally biased test content can affect results.

The Many Sources of Bias

• Culturally biased test processes exist.
• Stereotype threat occurs when negative stereotypes cause underperformance on ability tests.

Beliefs About Intelligence

• Entity theory is the belief that intelligence is fixed and difficult to change.
• Incremental theory is the belief that intelligence can be shaped by experiences, practice, and effort.

A More Useful Trait: Grit

• Grit involves perseverance of effort and working hard despite setbacks.
• Consistency of effort is sticking to a goal, even when other goals seem more attainable.

Intelligence as a Single Ability

• Spearman's general intelligence factor “g” represents a person's 'mental energy'.

Does "g" Tell The Whole Story?

• Savants have low mental capacity in most domains but extraordinary abilities in specific areas like music, mathematics, or art.

Intelligence as Multiple Abilities

• Spearman's two-factor model includes:
  • “g”: general intelligence.
  • “s”: specific-level, skill-based intelligence.
• Thurstone re-examined Spearman's tests and found 7 primary mental abilities.

Hierarchical Model of Intelligence

• Lower-level abilities (like “s” and those proposed by Thurman) are 'nested' within general intelligence.

Fluid and Crystallized Intelligence

• Fluid intelligence adapts to new situations and solves problems without relying on previous knowledge.
• Crystallized intelligence relies on extensive experience and knowledge, tending to be stable.

Multiple Intelligences Gone Awry

• Gardner's Multiple Intelligences Model proposes eight different forms of intelligence.
• This led to the idea of learning styles (e.g., visual learners learn more with visual materials).
• Very little scientific support exists for these models.

Brain Size and Intelligence

• Brain size was once believed to be related to intelligence.
• Einstein's brain was smaller than average.
• Well-developed white matter pathways were present in Einstein's brain

Convolutions of the Cortex

• Convolutions of the brain are associated with scores on WAIS.
• More gyri are present in species with more complex cognitive abilities.
• Avian brains lack convolutions but are also capable of complex cognition.

Relative Brain Size

• The modern human brain has the largest size relative to body weight.
• Relative brain size, neuron density, and organization allow complex cognitive processes.

Sex Differences

• No difference in average intelligence scores exists between sexes.
• Slight differences appear in sub-scores, such as verbal vs spatial abilities.
• Some research finds more variation in men.

Concussion

• Concussion is diagnosed when there is a disturbance of consciousness without structural damage.
• This can cause broad scale brain trauma.

Post-Concussion Syndrome

• Previously, concussions were believed to cause no long-term damage.
• Post-concussion symptoms can last for weeks, months, or even years.
• 10-20% of patients have symptoms for >1 month.

Chronic Traumatic Encephalopathy

• CTE (punch-drunk syndrome) is caused by repeated sub-concussive hits accumulating brain damage over time.
• CTE can lead to dementia and cerebral scarring.
• CTE has been detected in 18-year-old football players.
• 29% of high school players who had died showed signs of CTE.
• Symptoms of CTE include Cognitive, behaviour, mood, and motor symptoms.

Concussion rest and academics

• Reduce activities that require concentration and attention (school work, video games).
• Adequate sleep and daytime rest are important.
• Gradual return to activities once symptom-free.
• 80-90% of concussions resolve in 7-10 days for adults.
• Increased susceptibility can cause future concussions with links to depression and dementia

Studying Genes Directly

• Gene knockout and transgenic mouse models help to study genes directly.

Birth Order Effects

• First-born children get the benefit of teaching.
• First-born men had slightly higher IQs than their respective younger siblings.

Socio-Economic Status

• Socio-economic status influences access to high quality schools.
• Low-income households are more likely to have stressors that distract from learning.
• IQ decreases in children during summer months.
• Access to enriching materials and adoption studies also play a role.

SES and Language

• Language skills contribute to scores on many intelligence tests.
• Skills depend on opportunities provided by the environment.

Health and Nutrition

• Healthy students attend school more frequently.
• Diet affects IQ even among affluent households.

The Flynn Effect

• The steady population increases in intelligence test scores over time.
• Familiarity with standardized testing improves test results.
• Better Information processing and an improved more resourceful environment contributes to higher test scores.
• Negative Flynn effect is also observed.

Nature and Nurture

• Racial superiority arguments ignore the role of the environment.
• Minority groups are more likely to live in conditions that prevent them from reaching their genetic potential.
• Test validity should measure what they intend to measure which includes:
  • Working memory
  • Processing speed
  • Attention
  • Motivation