Assessing Intelligence: IQ and Bell-Shaped Distribution

• Alfred Binet and Theodore Simon developed the first intelligence test in 1904 for the French government to identify children requiring special educational assistance

• Their test consisted of diverse items measuring mental age, which was then converted to an Intelligence Quotient (IQ)

• IQ is a person's mental age relative to their chronological age

• Bell-Shaped Distribution illustrates IQ scores, with 100 as the average

• In 1916, Lewis Terman modified and standardized the Stanford-Binet IQ Test, which is still used today

• IQ tests can be administered to both children and adults, and include various items assessing reasoning, memory, and vocabulary

• Robert Yerkes used intelligence tests during World War I to place soldiers into suitable positions based on their cognitive abilities

• The Wechsler Adult Intelligence Scale-IV is a widely-used IQ test for those 16 and older, consisting of 15 subtests measuring various cognitive abilities

• The Wonderlic Personnel Test is a brief employment assessment test, measuring basic verbal and numerical abilities

• The Otis Self-Administering Test of Mental Ability is a test for students, measuring mathematical ability, language competency, and vocabulary

• Wechsler Intelligence Scale for Children assesses intelligence in younger children, and includes subtests for verbal comprehension, visual-spatial ability, and processing speed

• Computerized habilitats testing offers tailored testing and quick results, but requires a large number of test items and calibration

• Extremes of intelligence include intellectual disabilities, characterized by significant limitations in intellectual functioning and adaptive behavior, affecting about 1-3% of the population

• Intelligence tests must have both reliability and validity to accurately measure cognitive abilities.

• Mental retardation, also known as intellectual disabilities, can lead to gullibility.

• Intellectual disabilities come in various forms:

  • Mild: IQ of 55 to 69; 90% of all people with intellectual disabilities; able to hold jobs and families.
  • Moderate: IQ of 40 to 54; motor and language skill deficits; simple job.
  • Severe: IQ of 25 to 39; can not function independently.
  • Profound: IQ below 25.

• Causes of intellectual disabilities are both biological and environmental.

  • Biological: fetal alcohol syndrome, Down syndrome.
  • Environmental: familial intellectual disability, birth complications, lack of oxygen, diseases during pregnancy, poor nutrition, poor stimulation, maternal age, drug and alcohol use during pregnancy.

• Individuals with intellectual disabilities are entitled to a full education under the Education for All Handicapped Children Act and the 222 Law in Turkey.

• People with intellectual disabilities are entitled to education and training in the least restrictive environment, including mainstreaming and full inclusion.

• The 2% segment of the population known as the intellectually gifted have IQ scores above 130.

• Women and men differ in intelligence: women are better at verbal tasks, facial recognition, understanding expressions, and arithmetic calculation; men are better at spatial ability, mathematical tasks involving complex reasoning and geometry.

• African-Americans and Hispanic Americans score lower than Caucasians on average IQ tests, while Asian-Americans score higher. Jews have a slightly higher average IQ than non-Jews.

• Environmental factors, such as good water and light, can positively impact intellectual development, while minimal water and light can negatively impact it.

• Economically disadvantaged groups, such as Blacks, have a larger racial gap in intellectual development.

• Herrnstein and Murray's book "The Bell Curve" suggested that IQ differences between racial groups are genetic, but this is a controversial view.

• Racism plays a role in the racial gap in intellectual development.

• IQ differences between racial groups appear to be shrinking.

Explore the history, concepts, and methods of assessing intelligence, including IQ, mental age, and the bell-shaped distribution. Learn about the work of Alfred Binet and Theodore Simon in developing tests to identify children in need of special educational assistance.