Measurement of Intelligence

Overview

Measurement of intelligence is a foundational topic in Child Development and Pedagogy that directly impacts how teachers identify, support and evaluate learners with varying cognitive abilities. For TN TET, you must understand the concept of Intelligence Quotient (IQ), the major types of intelligence tests, their applications and limitations, and how these measures inform classroom practice.

This topic connects closely with theories of intelligence (Spearman, Gardner, etc.) and inclusive education. Questions typically test your knowledge of IQ formulas, names of standardised tests, their developers, and the educational implications of intelligence assessment. Expect 2-3 questions from this area, often requiring you to match tests with psychologists or identify appropriate uses of intelligence testing in schools.

Key Concepts

• **Intelligence Quotient (IQ)** is a numerical score derived from standardised tests designed to measure cognitive ability relative to age peers. It is not a fixed trait but can be influenced by environment, education and opportunity.

• **Mental Age (MA)** refers to the level of intellectual functioning compared to the average performance of children at various ages. A child with MA of 10 performs like an average 10-year-old regardless of actual age.

• **Chronological Age (CA)** is the actual age of a child in years and months, used as the baseline for calculating IQ in ratio-based formulas.

• **Normal Distribution** — IQ scores follow a bell curve with mean 100 and standard deviation 15-16. About 68% of people score between 85-115, and 95% score between 70-130.

• **Standardisation** means tests are administered under uniform conditions with established norms, ensuring scores can be compared meaningfully across individuals and groups.

• **Reliability** refers to the consistency of test results — a reliable test produces similar scores when repeated under similar conditions.

• **Validity** indicates whether a test actually measures what it claims to measure — true intelligence rather than just learned knowledge or cultural familiarity.

• **Culture-fair tests** attempt to minimise the influence of language, education and cultural background on intelligence measurement.

Formulas / Key Facts

**IQ Formula (Ratio IQ — Stern and Terman):** IQ = (Mental Age / Chronological Age) × 100

Example: A child aged 10 years with mental age of 12 years has IQ = (12/10) × 100 = 120

**Deviation IQ (Wechsler):** IQ = 100 + 15 × [(Individual Score − Mean Score) / Standard Deviation]

This method compares performance to same-age peers rather than using mental age.

**IQ Classification (commonly used):**

• Above 140: Genius/Near genius
• 120-140: Very superior/Gifted
• 110-119: Superior
• 90-109: Normal/Average
• 80-89: Dull normal
• 70-79: Borderline
• Below 70: Intellectually disabled

**Major Intelligence Tests and Developers:**

| Test | Developer | Type | |------|-----------|------| | Binet-Simon Scale | Alfred Binet & Theodore Simon (1905) | Individual, verbal | | Stanford-Binet Test | Lewis Terman (1916) | Individual, verbal | | WAIS (Wechsler Adult Intelligence Scale) | David Wechsler | Individual, verbal + performance | | WISC (Wechsler Intelligence Scale for Children) | David Wechsler | Individual, verbal + performance | | Raven's Progressive Matrices | John Raven | Group, non-verbal/culture-fair | | Army Alpha & Beta Tests | Developed during WWI | Group tests (Alpha-verbal, Beta-non-verbal) |

Worked Examples

**Example 1: Calculating IQ** A student aged 8 years solves problems that an average 10-year-old can solve. Calculate the IQ.

Solution:

• Mental Age (MA) = 10 years
• Chronological Age (CA) = 8 years
• IQ = (MA/CA) × 100 = (10/8) × 100 = 125

Interpretation: The child has superior intelligence.

**Example 2: Identifying appropriate test** A teacher wants to assess the intelligence of a group of 30 students from diverse linguistic backgrounds quickly. Which test is most suitable?

Solution: Raven's Progressive Matrices is most appropriate because:

• It is a group test (can assess many students simultaneously)
• It is non-verbal and culture-fair (minimises language bias)
• It uses visual patterns, making it suitable for diverse linguistic groups

**Example 3: Interpreting IQ distribution** In a class of 100 students with normally distributed IQ scores (mean 100, SD 15), approximately how many students will have IQ between 85 and 115?

Solution: The range 85-115 represents one standard deviation on either side of the mean. In a normal distribution, approximately 68% of scores fall within this range. 68% of 100 = 68 students

Common Mistakes

• **Treating IQ as fixed and unchangeable** → IQ can be influenced by educational intervention, enriched environments and proper nutrition. Teachers should view it as a current indicator, not a permanent label.

• **Using only verbal tests for all students** → Verbal tests disadvantage children from different linguistic backgrounds or those with language difficulties. Use performance-based or culture-fair tests when appropriate.

• **Equating IQ with overall worth or potential** → IQ measures only certain cognitive abilities. It does not capture creativity, emotional intelligence, practical skills or multiple intelligences identified by Gardner.

• **Confusing Mental Age with Chronological Age in calculations** → Remember: MA goes in the numerator (top), CA in the denominator (bottom). Reversing them gives incorrect IQ values.

• **Assuming ratio IQ works for adults** → Ratio IQ (MA/CA × 100) becomes meaningless for adults as mental age plateaus. Deviation IQ (comparing to same-age peers) is used instead.

• **Over-reliance on single test scores** → A single IQ test provides limited information. Multiple assessments over time, combined with observation and other evaluation methods, give a fuller picture.

Quick Reference

• IQ = (Mental Age / Chronological Age) × 100 — the classic Stern-Terman formula

• Average IQ = 100; scores 90-109 are considered normal range

• Stanford-Binet (Terman) — first widely used individual IQ test adapted for American population

• Wechsler tests (WAIS/WISC) use Deviation IQ and include both verbal and performance subtests

• Raven's Progressive Matrices — best choice for culture-fair, non-verbal group assessment

• Intelligence tests should inform teaching strategies, not label or limit children's opportunities