The Wisconsin Card Sorting Test (WCST) is a neuropsychological test of executive function: a person sorts cards by colour, shape or number without being told the rule, learns it only from “right” and “wrong” feedback, and has to notice when the rule silently changes. It was published in 1948 by Esta Berg and David Grant and is still one of the most widely used tests of flexible thinking. Its best-known score, perseverative errors, counts how often a person keeps following a rule after it has stopped working. It is not an IQ test, but its results are closely tied to fluid intelligence.
How the test works
Four key cards are laid out in front of the person. They show a red triangle, two green stars, three yellow crosses and four blue circles. The person then receives response cards — two decks of 64 in the standard version — each of which could match a key card by colour, by shape or by number of symbols.
- The person places each response card under the key card they think it belongs with. Nobody tells them the rule.
- After every card the examiner says only “right” or “wrong”. From that feedback alone the person has to work out whether the rule is colour, shape or number.
- After a run of correct sorts — ten in a row in the standard version, six in the Modified WCST — the rule changes without warning. Suddenly the sort that was right is wrong.
- The person has to notice the change, drop the old rule and find the new one. Each completed run counts as one category.
Esta Berg introduced the method in 1948 as “a simple objective technique for measuring flexibility in thinking”, and the same year she and David Grant described it as a card-sorting problem in the tradition of the older Weigl sorting task. The test’s central idea has not changed since: it measures what happens when a strategy that was being rewarded stops being rewarded.
Versions of the test
| Version | Cards | Run needed before the rule changes |
|---|---|---|
| Standard WCST (manual by Heaton and colleagues, 1993) | Up to 128 | 10 correct in a row |
| WCST-64 | 64 | 10 correct in a row |
| Modified WCST (after Nelson, 1976) | 48 | 6 correct in a row |
The Modified WCST also removes the ambiguous cards of the standard deck — those that match a key card on more than one feature — so every sort points to a single rule. The publisher gives the standard test’s range as ages 6½ to 89, with norms from 899 healthy children, adolescents and adults, and an administration time of about 20 to 30 minutes. A computer version exists, but it is sold to qualified professionals like the card version.
How the Wisconsin Card Sorting Test is scored
The WCST produces several scores rather than one. The most important are:
- Categories completed — how many runs of correct sorts the person achieved;
- Perseverative errors — failures to shift in response to negative feedback, usually sorting by a rule that has stopped being correct;
- Non-perseverative errors — all the other mistakes;
- Set-loss errors (failures to maintain set) — abandoning a rule that is still correct, even though the feedback has been positive.
Raw scores are converted into standard scores, T-scores and percentiles that compare the person with others of the same age, so there is no single “pass mark”. A high number of perseverative errors is the pattern the test is best known for, but what it means depends on the person’s age, education and history — which is why only a qualified professional interprets it.
Are the scores reliable? For a long time this was surprisingly unclear. A 2021 study from Hannover Medical School tested 146 neurological inpatients with the Modified WCST and found split-half reliabilities of .90 or higher for the number of correct sorts, categories and perseverative errors — the range normally wanted for individual decisions.
What the test measures — and what it does not
The WCST is usually described as a test of cognitive flexibility, one of the core executive functions. A landmark 2000 study by Akira Miyake and colleagues supports that: of the three executive functions it separated, WCST performance related most strongly to shifting. But the test also calls on working memory (remembering which rules have already been tried) and on abstract reasoning.
For decades the WCST was treated as a “frontal lobe test”. The evidence behind that label is mixed:
- A 2003 meta-analysis by George Demakis found that people with frontal lobe damage performed worse than people with damage further back in the brain on every WCST score except non-perseverative errors, with the largest difference for damage to the dorsolateral frontal cortex. It found no difference between left and right frontal damage.
- A 2009 review by Erika Nyhus and Francisco Barceló concluded that, in its traditional form, the test fails to discriminate between frontal and non-frontal lesions, and that brain imaging shows rapid, widespread activity across frontal and non-frontal regions while people do it.
So a poor WCST result says that something in a widely distributed system is not working as expected. It does not locate the problem, and it cannot diagnose any condition by itself.
The Wisconsin Card Sorting Test and IQ
The WCST gives no IQ score, but its link to intelligence is strong. In 2010 Maria Roca and colleagues compared patients with frontal lobe lesions and healthy controls on a range of executive tests. For the Wisconsin Card Sorting Test, they found that “fluid intelligence entirely explains frontal deficits”: when patients and controls were matched on fluid intelligence, no further frontal deficit remained.
In other words, much of what the WCST picks up is the same general ability to solve new problems that fluid intelligence tests and pattern tests such as Raven’s Progressive Matrices measure — the ability that the g factor describes. That is why a psychologist reads a WCST result alongside an IQ or reasoning score, not instead of one.
Can you take the Wisconsin Card Sorting Test online?
You can find free card-sorting tasks online, including open-source versions used in research. They follow the same idea, and trying one shows you what the test feels like. But they are not the published WCST: their cards, rules and scoring may differ, and they have none of its age norms. Without norms a raw count of errors cannot tell you how you compare with other people, so the number means little on its own.
The IQ Revealed test is an online reasoning test of 40 original items. It is not the Wisconsin Card Sorting Test, uses none of its materials, is not normed against it and does not measure executive function or diagnose anything. Our guides to how IQ tests work and how accurate IQ tests are explain what an online test can and cannot tell you.
Trust and scope notes
This page explains a neuropsychological test in general terms. The Wisconsin Card Sorting Test is used within clinical and research assessments; only a qualified professional can administer and interpret it for an individual, and nothing on this page, or our own test, can stand in for that or for a diagnosis. If you are worried about your own or someone else’s thinking or memory, a doctor is the right first step. Our IQ test is for adults aged 18 and over.
IQ Revealed is not affiliated with, endorsed by or connected to the publisher of the Wisconsin Card Sorting Test, the University of Wisconsin, or the researchers and institutions named on this page. “Wisconsin Card Sorting Test”, “WCST” and “Raven’s Progressive Matrices” are used only to identify the tests being described.