What is IQ? (Intelligence Quotient)

IQ tests definition and criticisms

IQ, or intelligence quotient, is a score derived from standardized tests designed to measure human intelligence.

The concept of IQ was developed to assess cognitive abilities and predict educational performance and job success. An IQ test typically evaluates various types of cognitive abilities including problem-solving, logical reasoning, memory, and comprehension (Kaufman, 2009; Ritchie, 2015).

One of the core aspects of the IQ test is its ability to provide a numerical representation of a person’s cognitive ability compared to the general population. Scores are usually standardized with an average score set at 100, and the majority of people scoring between 85 and 115 (Kaufman, 2009). This standardization means that an individual’s score reflects where they stand in relation to a typical norm group.

1.What is IQ?

1.1 Definition

Intelligence Quotient (IQ) is a numerical measure of a person’s cognitive abilities in relation to their age group, derived from standardized tests (Eysenck, 2018). These tests evaluate various cognitive skills, including logical reasoning, problem-solving, memory, and comprehension. An IQ score aims to predict a person’s potential to think logically, solve problems, and grasp complex ideas compared to the general population. The average IQ score is set at 100, with scores above or below this value indicating higher or lower cognitive ability, respectively.

1.2 Origins

The origins of IQ tests trace back to the early 20th century, initiated by the efforts of French psychologist Alfred Binet (Eysenck, 2018). Commissioned by the French Ministry of Education, Binet was tasked with developing a methodological approach to identify schoolchildren requiring specialized educational assistance. The resulting assessment focused on evaluating cognitive abilities such as attention, memory, and problem-solving skills.

Subsequently, this framework was adapted and expanded in the United States by Lewis Terman, a psychologist at Stanford University. Terman’s revisions culminated in the creation of the Stanford-Binet Intelligence Scales (Kaufman, 2009). This adaptation introduced the concept of an “intelligence quotient” (IQ), which quantifies intelligence relative to age-matched peers. The IQ score, derived from this test, is intended to reflect an individual’s cognitive ability compared to the normative average of their age group (Eysenck, 2018).

2. Uses of IQ Tests

IQ tests are utilized across various domains, each focusing on assessing cognitive abilities tailored to specific needs.

In educational settings, IQ tests play a crucial role in determining student placement. Schools use these tests to identify students who may benefit from special education services or advanced programs for gifted and talented individuals. This helps educators provide a more customized educational experience that aligns with each student’s unique cognitive abilities.

In the employment sector, IQ tests are often employed as part of the screening process. Employers use these assessments to evaluate a candidate’s problem-solving skills and overall cognitive aptitude, particularly for positions that demand high levels of analytical thinking and complex problem-solving abilities. This can assist in selecting the most suitable candidates for specific job roles.

Additionally, IQ tests are instrumental in psychological and neurological evaluations. Medical professionals and psychologists utilize these tests to assess the impact of brain injuries, neurological diseases, or developmental disorders on an individual’s cognitive functions. This is vital for diagnosing conditions, planning treatments, and implementing appropriate support measures for affected individuals.

3. Critique and Criticisms of IQ Tests

The concept of IQ has been subject to significant critique.

Critics argue that IQ tests are not fully capable of capturing the multidimensional nature of human intelligence. Intelligence is more complex than what can be measured in timed tests and includes creativity, emotional awareness, practical problem-solving, and social sensitivity, none of which are adequately assessed by traditional IQ tests (Benisz, Willis, & Dumont, 2019).

Another major concern is the potential cultural bias inherent in IQ tests (Reynolds, Altmann & Allen, 2021). Many argue that these tests are designed with certain cultural knowledge in mind, which can disadvantage individuals from different backgrounds or education systems (Heingartner, 2020).

This leads to questions about the fairness and universality of IQ as a measure of intelligence. For example, a question that requires knowledge of specific cultural references or vocabulary may not be a fair measure of intelligence for someone who was raised in a different cultural context (Reynolds, Altmann & Allen, 2021).

Additionally, there is the issue of the stability of IQ scores.

Research suggests that while IQ scores are somewhat stable over time, they are not completely fixed (Benisz, Willis, & Dumont, 2019). Factors such as education, socioeconomic status, and even nutrition can significantly affect a person’s test performance. This variability challenges the idea that IQ is an immutable measure of cognitive capability.

The use of IQ scores to predict life outcomes is another area of controversy. While there is evidence to suggest that higher IQ scores correlate with better academic and career success, the relationship is not absolute.

There are many instances where individuals with average or below-average IQ scores achieve high levels of success, and conversely, those with high IQ scores do not always reach high levels of achievement (Kaufman, 2018). This indicates that other factors, such as personality traits, work ethic, social skills, and opportunities, play critical roles in one’s success.

Moreover, the historical misuse of IQ testing has left a dark legacy, with tests once used to justify eugenics theories or discriminatory practices. In the early 20th century, IQ tests were employed to support arguments for immigration restrictions and forced sterilizations, practices now widely condemned as unethical and scientifically unfounded (Benisz, Willis, & Dumont, 2019; Kaufman, 2009).

In response to these criticisms, the field of intelligence testing has evolved. Modern tests often strive to be more culturally neutral and are designed to measure a broader range of cognitive abilities (Kaufman, 2018). Furthermore, there is an increasing focus on developing assessments that better capture the complex and dynamic nature of intelligence.


While IQ tests can provide valuable information about certain aspects of cognitive ability, they are not definitive measures of a person’s overall intelligence or potential. The ongoing debate and research in the field of intelligence highlight the complexity of measuring cognitive abilities and the importance of considering a wide range of factors when evaluating individual capabilities and potential. This understanding encourages a more holistic approach to education and workforce development, recognizing the diverse talents and abilities that contribute to individual and societal success.


Benisz, M., Willis, J. O., & Dumont, R. (2019). 16 Abuses and Misuses of Intelligence Tests. In Kaufman, A. B., & Kaufman, J. C. (Eds.). (2018). Pseudoscience: The conspiracy against science. Mit Press.

Eysenck, H. (2018). Intelligence: A new look. Routledge.

Heingartner, D. (2020, August 29). Defeating the IQ test. New Scientist, 247(3297), 19. https://doi.org/10.1016/S0262-4079(20)31487-1

Kaufman, A. S. (2009). IQ testing 101. Springer Publishing Company.

Kaufman, A. S. (2018). Many pathways, one destination: IQ tests, intelligent testing, and the continual push for more equitable assessments.

Reynolds, C. R., Altmann, R. A., & Allen, D. N. (2021). The problem of bias in psychological assessment. In Mastering modern psychological testing: Theory and methods (pp. 573-613). Cham: Springer International Publishing.

Ritchie, S. (2015). Intelligence: All that matters. John Murray.

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Dr. Chris Drew is the founder of the Helpful Professor. He holds a PhD in education and has published over 20 articles in scholarly journals. He is the former editor of the Journal of Learning Development in Higher Education. [Image Descriptor: Photo of Chris]

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