IQ tests are the most widely used measure of cognitive ability, yet they're often misunderstood. What do they actually measure? How are scores calculated? This guide answers all your questions about IQ testing.
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IQ stands for "Intelligence Quotient." Originally, it was calculated as: (Mental Age / Chronological Age) × 100. Modern IQ tests use a "deviation IQ" method, comparing your performance to others of the same age. The average is set at 100, with a standard deviation of 15 points.
IQ attempts to measure general cognitive ability—the capacity to learn, reason, solve problems, and adapt to new situations.
A Brief History of IQ Testing
1905: French psychologist Alfred Binet created the first practical intelligence test to identify students needing educational support.
1916: Lewis Terman adapted Binet's test for American use, introducing the IQ formula (Stanford-Binet).
1939: David Wechsler developed new tests that measured verbal and non-verbal abilities separately. The Wechsler tests remain the gold standard today.
How IQ Tests Are Scored
Modern IQ tests use a bell curve (normal distribution):
- Mean (average): 100
- Standard deviation: 15
- 68% of people: Score between 85-115
- 95% of people: Score between 70-130
IQ Score Ranges
| 130+ | Very Superior (2.1%) |
| 120-129 | Superior (6.7%) |
| 110-119 | High Average (16.1%) |
| 90-109 | Average (50%) |
| 80-89 | Low Average (16.1%) |
| 70-79 | Borderline (6.7%) |
What IQ Tests Actually Measure
Most modern IQ tests measure several cognitive abilities:
- Verbal Comprehension: Understanding language, vocabulary, verbal reasoning
- Perceptual Reasoning: Visual-spatial processing, pattern recognition
- Working Memory: Holding and manipulating information in short-term memory
- Processing Speed: How quickly you can process simple visual information
What IQ Predicts (and What It Doesn't)
What IQ Predicts Well
- Academic performance
- Job training success
- Job performance in complex roles
What IQ Doesn't Predict Well
- Creativity (beyond a threshold)
- Emotional intelligence
- Wisdom and good judgment
- Character and integrity
- Happiness and life satisfaction
Curious About Your IQ Score?
Our IQ assessment measures fluid intelligence, logical reasoning, and pattern recognition.
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Evidence suggests some possibilities:
- Education: Each year of education raises IQ by about 1-5 points
- Physical exercise: Improves blood flow to the brain
- Cognitive challenge: Engaging in mentally stimulating activities
- Quality sleep: Essential for cognitive function
For more on improving cognitive abilities, see our guide to neuroplasticity and brain training.
IQ vs. Other Types of Intelligence
IQ measures cognitive intelligence, but other forms matter too:
- Emotional Intelligence (EQ)
- Social Intelligence
- Practical Intelligence
- Creative Intelligence
Success depends on many factors. IQ is one piece of the puzzle, not the whole picture.
Conclusion
IQ tests measure important cognitive abilities—pattern recognition, logical reasoning, verbal comprehension. These abilities correlate with academic and career success.
However, IQ is not destiny. It doesn't measure creativity, emotional intelligence, character, or many other qualities that matter for success and happiness. Use IQ as one data point for self-understanding—not as a limit on what you can achieve.
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