An intelligence test, also known as a cognitive ability test or IQ test, is one of the strongest predictors of job performance available to a recruiter. At the same time, it is a tool that is easily misused. It can discourage good candidates, unintentionally disadvantage certain groups, or lead to a misread score. These eight insights, based on scientific research, show how to use an intelligence test smartly and fairly in hiring and selection.
| Do | Don't |
|---|---|
| ✓ Treat the score as 'enough cognitive ability for the role,' not a competition | ✗ Don't automatically pick the highest scorer |
| ✓ Determine per role how much cognitive ability is really needed | ✗ Don't use a long, off-putting test for scarce candidates |
| ✓ Always combine the test with an interview or work sample | ✗ Don't rely on an unproctored take-home test for high-stakes decisions |
| ✓ Let candidates practice beforehand so everyone starts equal | ✗ Don't confuse language proficiency with cognitive ability |
| ✓ Consider a work sample for scarce senior roles | ✗ Don't compare everyone with the same yardstick |
| ✓ Watch whether the test unintentionally disadvantages groups | ✗ Don't assume one test tells the whole story |
No. People who score higher on an intelligence test perform somewhat better on average, but somewhat better on average is not the same as always the best choice. In practice, selecting purely on the highest score rarely pays off.
The more important question is whether a candidate has enough cognitive ability for the specific role. A data analyst must constantly solve new, complex problems, so cognitive ability matters heavily there. A role that is largely bound by procedures requires less. Someone far above the level of the role may also become bored and leave sooner.
Source: Schmidt & Hunter, 1998; Sackett et al., 2022
For many roles, the value of a good measurement outweighs a bit of resistance. But for scarce and senior profiles, that is different. Those candidates are often approached directly, they have options, and a test that feels impersonal can be a reason for them to drop out.
A good work sample or case study often measures the same thing as an intelligence test, but feels more relevant because it visibly relates to the actual job. Choose the test format based on the role, light and relevant where you need to attract candidates, extensive where you need certainty.
Source: Hausknecht et al., 2004
This is one of the most important considerations when using intelligence tests. On these tests, some groups score lower on average, not because they are less capable of doing the work, but due to differences in education, language, and background, among other factors. Selecting purely on score can therefore unintentionally exclude people who would do the job perfectly well.
That is not only unfair, it is also a compliance risk. In the Netherlands and the EU, rules such as the GDPR and the EU AI Act require that selection be explainable and non-discriminatory. Never use the test as the only filter, combine it with interviews and work samples. Where possible, choose test formats with little language, work with a threshold per role instead of a strict ranking, and monitor whether certain groups drop out more often.
Source: Ployhart & Holtz, 2008; Roth et al., 2001
In the past, a test someone took at home was usually fine. That has changed. AI tools can now answer many classic test questions fluently, so with an unproctored test you can no longer be sure whether you are measuring the candidate's cognitive ability or that of a chatbot.
Proctoring has therefore become more important for decisions that really matter. Note the downside though, heavy proctoring feels uncomfortable and touches on privacy. Use it only where the stakes are high enough. Effective measures include a test where everyone gets different questions, strict timing, and for high-stakes decisions, a proctored or verified administration.
No, and this is a common mistake. Many tests include language questions, reasoning with words, concepts, and texts. For roles where language is central, such as legal, sales, or advisory work, that makes sense.
But language questions sometimes confuse language proficiency with intelligence. Someone who does not have the language as their native tongue may score lower due to the language, not due to less cognitive ability. Language-heavy questions in particular increase the chance of unintentionally disadvantaging groups. The rule of thumb is to ask yourself whether language is truly necessary for the role. If not, choose a test that relies more on figures and numbers.
Source: Ployhart & Holtz, 2008
Yes, and that is actually fair. Someone who has never taken such a test loses points due to unfamiliarity with the question format, time pressure, and pace. That has nothing to do with cognitive ability. Someone who has taken tests before has an unfair advantage as a result.
Research shows that practicing raises the score slightly, especially the first time, and that this effect flattens out quickly after that. That is exactly why the advice is to let all candidates practice beforehand. Then everyone starts from the same line and you compare apples to apples.
Source: Hausknecht et al., 2007
Yes, but with nuance. Cognitive ability roughly consists of two types. Quickly cracking new, abstract problems is at its strongest at a younger age and gradually declines afterward. Knowledge and experience, on the other hand, stays strong for a long time or even keeps growing.
A test that relies mainly on fast, abstract puzzles turns out somewhat less favorably for older candidates on average, while they can be strong in experience and judgment. Compare with an appropriate group instead of measuring everyone with the same yardstick, and do not automatically read a lower score on a speed test as less suitable.
Source: Horn & Cattell, 1967; Salthouse, 2009
An adaptive test adjusts itself to the candidate while it is being taken. Correct answers make the following questions harder, less correct answers make them easier. This way the test quickly finds the candidate's true level.
This type of test is shorter but equally reliable, less burdensome for the candidate, and harder to cheat because almost everyone gets different questions. That last point is also a direct answer to the AI issue from the previous point.
An intelligence test is valuable but not a magic wand. Use it as one signal alongside others, such as personality assessments, work sample cases, and an AI chat intake. Selection Lab combines these building blocks in one Selection Flow, so you can set the right balance per role between measurement power, candidate experience, and fairness.
An intelligence test, also known as a cognitive ability test or IQ test, measures cognitive skills such as numerical, verbal, and abstract reasoning. It is one of the strongest predictors of job performance and is used to assess whether a candidate has enough cognitive ability for a specific role.
No. A higher score predicts somewhat better performance on average, but that does not mean the highest score is always the best choice. The more important question is whether a candidate has enough cognitive ability for the specific role. Someone far above the level may become bored and leave sooner.
Intelligence tests show average score differences between groups that are not caused by differences in ability to do the work, but by factors such as education, language, and background. Never use the test as the only filter, combine it with interviews and work samples, and choose test formats with little language where possible.
Yes. Modern AI models can fluently answer many classic test questions, meaning an unproctored take-home test no longer reliably measures the candidate's cognitive ability. Proctoring, adaptive test formats, and verified checks for high-stakes decisions reduce this risk.
Yes. Practicing raises the score slightly, especially the first time, and this effect flattens quickly. Letting all candidates practice beforehand means everyone starts from the same position, making the comparison fairer.
An adaptive test adjusts the difficulty of questions based on previous answers. This makes the test shorter, more pleasant for the candidate, and harder to cheat because almost everyone gets different questions.
Yes. An intelligence test is one signal alongside others. Combine the test with interviews, work samples, or assessments to get a more complete and fairer picture of a candidate's suitability.
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An intelligence test, also known as a cognitive ability test or IQ test, is one of the strongest predictors of job performance available to a recruiter. At the same time, it is a tool that is easily misused. It can discourage good candidates, unintentionally disadvantage certain groups, or lead to a misread score. These eight insights, based on scientific research, show how to use an intelligence test smartly and fairly in hiring and selection.
| Do | Don't |
|---|---|
| ✓ Treat the score as 'enough cognitive ability for the role,' not a competition | ✗ Don't automatically pick the highest scorer |
| ✓ Determine per role how much cognitive ability is really needed | ✗ Don't use a long, off-putting test for scarce candidates |
| ✓ Always combine the test with an interview or work sample | ✗ Don't rely on an unproctored take-home test for high-stakes decisions |
| ✓ Let candidates practice beforehand so everyone starts equal | ✗ Don't confuse language proficiency with cognitive ability |
| ✓ Consider a work sample for scarce senior roles | ✗ Don't compare everyone with the same yardstick |
| ✓ Watch whether the test unintentionally disadvantages groups | ✗ Don't assume one test tells the whole story |
No. People who score higher on an intelligence test perform somewhat better on average, but somewhat better on average is not the same as always the best choice. In practice, selecting purely on the highest score rarely pays off.
The more important question is whether a candidate has enough cognitive ability for the specific role. A data analyst must constantly solve new, complex problems, so cognitive ability matters heavily there. A role that is largely bound by procedures requires less. Someone far above the level of the role may also become bored and leave sooner.
Source: Schmidt & Hunter, 1998; Sackett et al., 2022
For many roles, the value of a good measurement outweighs a bit of resistance. But for scarce and senior profiles, that is different. Those candidates are often approached directly, they have options, and a test that feels impersonal can be a reason for them to drop out.
A good work sample or case study often measures the same thing as an intelligence test, but feels more relevant because it visibly relates to the actual job. Choose the test format based on the role, light and relevant where you need to attract candidates, extensive where you need certainty.
Source: Hausknecht et al., 2004
This is one of the most important considerations when using intelligence tests. On these tests, some groups score lower on average, not because they are less capable of doing the work, but due to differences in education, language, and background, among other factors. Selecting purely on score can therefore unintentionally exclude people who would do the job perfectly well.
That is not only unfair, it is also a compliance risk. In the Netherlands and the EU, rules such as the GDPR and the EU AI Act require that selection be explainable and non-discriminatory. Never use the test as the only filter, combine it with interviews and work samples. Where possible, choose test formats with little language, work with a threshold per role instead of a strict ranking, and monitor whether certain groups drop out more often.
Source: Ployhart & Holtz, 2008; Roth et al., 2001
In the past, a test someone took at home was usually fine. That has changed. AI tools can now answer many classic test questions fluently, so with an unproctored test you can no longer be sure whether you are measuring the candidate's cognitive ability or that of a chatbot.
Proctoring has therefore become more important for decisions that really matter. Note the downside though, heavy proctoring feels uncomfortable and touches on privacy. Use it only where the stakes are high enough. Effective measures include a test where everyone gets different questions, strict timing, and for high-stakes decisions, a proctored or verified administration.
No, and this is a common mistake. Many tests include language questions, reasoning with words, concepts, and texts. For roles where language is central, such as legal, sales, or advisory work, that makes sense.
But language questions sometimes confuse language proficiency with intelligence. Someone who does not have the language as their native tongue may score lower due to the language, not due to less cognitive ability. Language-heavy questions in particular increase the chance of unintentionally disadvantaging groups. The rule of thumb is to ask yourself whether language is truly necessary for the role. If not, choose a test that relies more on figures and numbers.
Source: Ployhart & Holtz, 2008
Yes, and that is actually fair. Someone who has never taken such a test loses points due to unfamiliarity with the question format, time pressure, and pace. That has nothing to do with cognitive ability. Someone who has taken tests before has an unfair advantage as a result.
Research shows that practicing raises the score slightly, especially the first time, and that this effect flattens out quickly after that. That is exactly why the advice is to let all candidates practice beforehand. Then everyone starts from the same line and you compare apples to apples.
Source: Hausknecht et al., 2007
Yes, but with nuance. Cognitive ability roughly consists of two types. Quickly cracking new, abstract problems is at its strongest at a younger age and gradually declines afterward. Knowledge and experience, on the other hand, stays strong for a long time or even keeps growing.
A test that relies mainly on fast, abstract puzzles turns out somewhat less favorably for older candidates on average, while they can be strong in experience and judgment. Compare with an appropriate group instead of measuring everyone with the same yardstick, and do not automatically read a lower score on a speed test as less suitable.
Source: Horn & Cattell, 1967; Salthouse, 2009
An adaptive test adjusts itself to the candidate while it is being taken. Correct answers make the following questions harder, less correct answers make them easier. This way the test quickly finds the candidate's true level.
This type of test is shorter but equally reliable, less burdensome for the candidate, and harder to cheat because almost everyone gets different questions. That last point is also a direct answer to the AI issue from the previous point.
An intelligence test is valuable but not a magic wand. Use it as one signal alongside others, such as personality assessments, work sample cases, and an AI chat intake. Selection Lab combines these building blocks in one Selection Flow, so you can set the right balance per role between measurement power, candidate experience, and fairness.
An intelligence test, also known as a cognitive ability test or IQ test, measures cognitive skills such as numerical, verbal, and abstract reasoning. It is one of the strongest predictors of job performance and is used to assess whether a candidate has enough cognitive ability for a specific role.
No. A higher score predicts somewhat better performance on average, but that does not mean the highest score is always the best choice. The more important question is whether a candidate has enough cognitive ability for the specific role. Someone far above the level may become bored and leave sooner.
Intelligence tests show average score differences between groups that are not caused by differences in ability to do the work, but by factors such as education, language, and background. Never use the test as the only filter, combine it with interviews and work samples, and choose test formats with little language where possible.
Yes. Modern AI models can fluently answer many classic test questions, meaning an unproctored take-home test no longer reliably measures the candidate's cognitive ability. Proctoring, adaptive test formats, and verified checks for high-stakes decisions reduce this risk.
Yes. Practicing raises the score slightly, especially the first time, and this effect flattens quickly. Letting all candidates practice beforehand means everyone starts from the same position, making the comparison fairer.
An adaptive test adjusts the difficulty of questions based on previous answers. This makes the test shorter, more pleasant for the candidate, and harder to cheat because almost everyone gets different questions.
Yes. An intelligence test is one signal alongside others. Combine the test with interviews, work samples, or assessments to get a more complete and fairer picture of a candidate's suitability.
