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Elements of an IQ Test

Elements of an IQ Test

Intelligence Quotient tests have long been a widely-used tool to evaluate a person's cognitive abilities. The primary purpose of IQ tests is to measure an individual's mental faculties in relation to their age, providing a standardized score that can be used for various purposes such as educational placement, identifying learning difficulties, or assessing intellectual potential.

Components of IQ Tests

IQ tests are often divided into four areas: verbal comprehension, perceptual reasoning, working memory, and processing speed. Each of these areas assesses different cognitive abilities and contributes to the overall IQ score. 

It's worth mentioning that different IQ tests may categorize or name these components differently. For example, the Wechsler Intelligence Scale for Children (WISC) includes Verbal Comprehension, Perceptual Reasoning, Working Memory, and Processing Speed. In contrast, the Stanford-Binet Intelligence Scales consider five factors: Knowledge, Quantitative Reasoning, Visual-Spatial Processing, Working Memory, and Fluid Reasoning.

IQ tests usually measure various components of intelligence, each with its own set of subtests. Although the components and subtests can vary by test, the following is a general breakdown using commonly accepted categories.

IQ test elements
Component Description Subtests/Examples
Verbal Reasoning Measures the ability to understand, interpret, and respond to verbal information. Vocabulary, Comprehension, Similarities
Perceptual Reasoning Measures the ability to interpret, analyze, and think critically about visual-spatial information. Block Design, Matrix Reasoning, Visual Puzzles
Working Memory Measures the ability to temporarily store, manipulate, and recall information. Digit Span, Arithmetic, Letter-Number Sequencing
Processing Speed Measures the speed and efficiency of mental and motor responses. Coding, Symbol Search
Quantitative Reasoning Often part of more comprehensive IQ tests, it measures the ability to use numerical concepts and perform arithmetic operations. Mathematical problems, Number series
Abstract Reasoning It assesses the ability to identify patterns, relationships, or logical rules in different scenarios. Figure Classification, Picture Arrangement

IQ tests usually measure various components of intelligence, each with its own set of subtests. Although the components and subtests can vary by test, the following is a general breakdown using commonly accepted categories.

Explanation of the subtests/examples listed in the table

  1. Vocabulary: This subtest measures word knowledge and verbal concept formation. The individual is asked to define a series of presented words. Difficulty increases as the test progresses.

  2. Comprehension: This measures verbal reasoning and conceptualization, verbal comprehension and expression, and the ability to evaluate and use past experience. The individual is presented with questions that assess comprehension of social situations, or understanding of common concepts.

  3. Similarities: This assesses verbal concept formation and reasoning. The test-taker is asked to describe how two seemingly different things or concepts are alike, requiring abstract thinking.

  4. Block Design: This subtest measures visual-motor coordination, visual-spatial processing, and the ability to separate visual fields into components. Test-takers are given blocks, which they must arrange according to a pattern.

  5. Matrix Reasoning: This task evaluates non-verbal reasoning, pattern recognition, and induction. It involves visual puzzles that the test-taker must complete.

  6. Visual Puzzles: This subtest measures nonverbal reasoning, spatial processing, and part-whole relationships. The individual is presented with a completed puzzle and asked to choose three options that, when combined, reconstruct the original puzzle.

  7. Digit Span: This measures working memory and concentration. The individual is required to repeat a sequence of numbers in the same order or reverse order, as presented by the examiner.

  8. Arithmetic: This evaluates mental computation, concentration, and working memory. The test-taker is asked to solve arithmetic problems within a given time frame without paper or pencil.

  9. Letter-Number Sequencing: This assesses working memory, cognitive flexibility, and attention. The individual is given a mixed series of numbers and letters and asked to recall the numbers in ascending order and the letters in alphabetical order.

  10. Coding: This is a timed task measuring processing speed, short-term visual memory, learning ability, psychomotor speed, and visual-motor coordination. Test-takers must match symbols and numbers using a key within a specified timeframe.

  11. Symbol Search: This assesses processing speed, short-term visual memory, and visual-motor coordination. Individuals must scan a search group and indicate whether one of the symbols matches the target symbol.

  12. Mathematical problems: This subtest measures the ability to solve mathematical problems, understanding of mathematical concepts, and numerical operations.

  13. Number series: This measures the ability to identify the underlying rule in a series of numbers and use that rule to determine the next number in the series.

  14. Figure Classification: This subtest assesses abstract reasoning and the ability to categorize. The individual is shown a series of figures and must identify which one doesn't belong or identify the missing figure.

  15. Picture Arrangement: This subtest evaluates logical/sequential reasoning, the ability to infer social cause-and-effect relationships and social judgment. The individual must arrange pictures to tell a story in a logical sequence.

Yuki Kojida

Psychometrician, co-owner of IGT
I am Yuki Kojida, a Japanese psychologist and one of the cofounders of I am really excited about the study of human cognitive abilities in different states for many years as well. This article is moderated and published by myself.