High-IQ quirks: nine viral habits traced to the study behind each

0 The short answer

Most viral high-IQ quirks do not trace to a study that measured IQ: the swearing studies measured word fluency, the messy desk experiment measured creativity ratings, and the self-talk experiments measured task performance. Where intelligence was measured, the links are specific and conditional, such as reflective pondering but not brooding going with higher scores in a twin study of 751 people, and the best known messy desk result was not reproduced in a 2019 experiment with 100 participants. A group average never tells you that a habit signals a high score in one person, so a quirk is a poor basis for judging anyone's intelligence, including your own.

1 What Would It Take for a Habit to Count as a Sign of High IQ?

A habit counts as a sign of high IQ only if someone measured the habit, measured IQ with a normed test, and found an association in a sample and design that can bear it, and most viral quirks fail the second or third condition. The conditions sound obvious, but a quick reading of the lists shows how rarely they are met. A study of swearing that scores how many taboo words a student can name in a minute has measured fluency. A study that gives people a tidy or a messy desk and rates their ideas has measured creativity ratings. Neither has an IQ score in it, so neither can say that high-IQ people do the thing.

Four questions separate a result about intelligence from a result that was only reported as one. The first is what was measured: a standardized test of general ability or of a broad ability such as those in the CHC model, or a nearby skill such as vocabulary, word retrieval or a creativity rating. The page on what IQ measures explains why a nearby skill is not the same thing. The second is the design: an observational survey can show that two things go together, while only random assignment, as in an experiment that gives people a messy or a tidy desk, can show that a condition changed an outcome in that sample. The third is the sample: undergraduates volunteering for credit are a narrow slice of adults, and a study of a few dozen people can produce a striking number by chance. The fourth is the size of the effect, because a true link can still be too small to use.

The size question deserves a number. The strongest personality correlate of intelligence in the largest meta-analysis of the topic, 272 studies and 162,636 people, is openness to experience at a population value of 0.20 (Anglim and colleagues 2022). By our arithmetic, squaring 0.20 gives 0.04, so about 4 percent of the variation in intelligence scores goes with the variation in openness. That is the best-supported personality link, and it is nowhere near a rule about individuals. A habit such as swearing or keeping a messy desk would need to beat that to be a useful sign, and the abstracts of the studies in this audit do not report a habit-level link of that size. The page on what IQ correlates with ranks eighteen sourced links by size, and the page on reliability and validity explains why a test score has to be trustworthy before any correlation with it means anything.

A last distinction keeps the audit honest. A statement about a group, such as "students who named more taboo words also named more animals," is not a statement about you. The sections below take each habit in turn, give the study that is usually cited, and report what it found, with the design and the sample.

2 The Nine-Habit Audit: Study, Design, Measure and Verdict

Across the nine habits, only three have a study that measured intelligence with a test, and none of those three supports reading the habit as a sign of a high score in one person. The table gives the study that is usually cited for each habit, the design and sample, what was measured, whether intelligence was measured, and what the result supports. Where this page found no study that relates the habit to an IQ score, the table says so, which is a statement about the search for this page and not a claim about the whole literature. Each row is expanded in the section named in its last column.

Three reading rules apply to every row. First, a "no" in the IQ column does not mean the habit is unrelated to intelligence; it means that the study cited for it cannot say. Second, the effect sizes in the abstracts of several of these studies are not reported there, and this page quotes only numbers that appear in the abstract or in a paper that describes the study, so some rows have a sample size but no coefficient. Third, the rows with an intelligence measure are the ones most open to the opposite error: reading a small group average as a rule.

The list itself is a product of how these claims spread. A local television station's story of August 5, 2016, headlined "Cursing, staying up late, being messy may be signs of intelligence", attributes three claims to three studies, reports no sample sizes, and does not say how IQ was measured. The same trio of swearing, late nights and messy desks appeared in other outlets' versions of the story, and a web search on October 20, 2026 still returns a Springer Nature community post whose title promises that people who are messy, love to swear and cannot sleep may be geniuses. A later section returns to why such lists travel so well. First, the evidence for each habit.

3 Do Smart People Swear More? What Taboo Word Fluency Measured

The swearing studies measured how many taboo words a person can name, they showed that this goes with general verbal fluency and vocabulary, and none of them measured IQ or how often anyone swears. The claim that smart people swear more usually traces to Kristin Jay and Timothy Jay, who published a set of fluency experiments in Language Sciences in 2015 (Jay and Jay 2015). Their target was a folk assumption, which they call the poverty-of-vocabulary myth: the idea that people use taboo words because they cannot find better words. They compared general verbal fluency, measured with the Controlled Oral Word Association Test, with taboo word fluency and animal word fluency, in spoken and in written formats. All three measures were positively correlated, which the authors read as support for a "fluency is fluency" account. In their data a set of 10 taboo words accounted for 55 to 60 percent of all taboo words produced, and there was no overall sex difference in taboo word generation.

Read closely, that is a result about word retrieval. A person who can generate many words in a category can generate many words in a taboo category too. It is a rebuttal of a stereotype, that swearers have small vocabularies, and it is not a finding that swearers have large ones, because the study asked people to name taboo words on request and did not record what they say in daily life. The same abstract reports that taboo fluency was positively correlated with the Big Five traits neuroticism and openness and negatively correlated with agreeableness and conscientiousness, so the measure carries personality information as well as verbal skill.

A later study put the question to a stricter test. Reiman and Earleywine ran a preregistered study with 266 undergraduates at a US university, with a mean age of 19.36, and measured swear word fluency, verbal fluency, vocabulary, Big Five traits, sensation seeking and drug use (Reiman and Earleywine 2023). Swear word fluency was positively associated with verbal fluency, vocabulary, openness and extraversion, and negatively associated with agreeableness. It also accounted for unique variance in self-reported drug use over and above personality and general verbal ability. The authors did not conclude that swearing marks intelligence. They concluded that swear word fluency does not come from a lack of verbal skill, and they suggested it might serve as an index of traits related to drug involvement.

Neither study gave participants an intelligence test, and neither measured how frequently anyone swears. Vocabulary is one component of a verbal profile, and the page on the Vocabulary subtest describes how a normed task samples it, while the page on verbal IQ tests explains how a verbal score is built from several tasks rather than from one list of words. A reasonable reading, and it is our reading and not the authors', is that the studies fit a modest overlap between word retrieval, vocabulary and the openness trait, which is also among the two strongest Big Five correlates of intelligence in the meta-analysis cited earlier. That is an inference about a pattern, not a measured link between swearing and IQ.

The viral version went further than the paper. A fact check by Lead Stories, published on July 31, 2019 and updated on August 1, 2019, addressed a post claiming that psychologists urge people to befriend those who swear a lot because they are smarter and more honest (Lead Stories 2019). It rated the claim false, reported that the fluency study did not show that people who swear more are smarter, and quoted Timothy Jay: "I cannot endorse that interpretation of my work." The lesson is the one the authors of the fluency study had already written into their design: knowing a word and using it often are different things, and the first does not imply a high score on anything else.

4 Do Messy Desks Signal Intelligence? One Experiment, One Replication

The messy desk claim rests on a creativity experiment from 2013 with roughly 20 to 25 people per group, no IQ test and a 2019 replication that found no significant difference. Kathleen Vohs, Joseph Redden and Ryan Rahinel reported three experiments in Psychological Science in 2013 (Vohs and colleagues 2013). In the first, participants in an orderly room chose healthier snacks and donated more money than participants in a disorderly room. In the second, participants in a disorderly room were more creative than participants in an orderly room. In the third, participants in an orderly room preferred an option labeled as classic and those in a disorderly room preferred an option labeled as new. The authors framed this as different environments suiting different outcomes, and the paper does not claim that messy people are intelligent.

The replication is where the numbers are clearest. Alberto Manzi and colleagues randomly assigned participants to an orderly or a messy desk and gave them two creativity measures and executive control tests (Manzi and colleagues 2019). They recruited 114 volunteers and analyzed 100, with a mean age of 22.89 years. On a standardized creativity composite the groups were close to identical, with a test statistic of t(98) = minus 0.314 and p = 0.75. A few creativity subtests came close to the usual threshold, with p-values between 0.05 and 0.09, but none met the stricter corrected threshold of 0.0125 the authors set for multiple tests. The paper describes the original study as using about 20 to 25 participants per group, where the replication had about 50 per group, and it lists differences in the setup: a different object in the idea task, a different rating scale, a short three-minute exposure and clutter on the desk only. Its conclusion is that the effect of a messy desk over a short period, if it exists, is small and unreliable, and that the claim does not justify the press coverage it received.

The replication is one study, with differences from the original, so it does not prove the original effect is zero. It does show that the claim is not settled, and that the version in the lists, "a messy desk is a sign of intelligence," is two steps beyond anything an experiment tested. The first step is from creativity ratings to IQ. A page on IQ and creativity covers how closely creativity test scores track intelligence, and the answer is that they are related but distinct. The second step is from an environment that was assigned to a person, as in both experiments, to a habit that a person chooses, as in the lists. A person who keeps a messy desk may differ from others in many ways that a randomized room does not capture.

There is one place where the personality literature touches this claim. In the meta-analysis of personality and intelligence, facet-level results showed that sociability and orderliness were negatively correlated with intelligence (Anglim and colleagues 2022). The abstract does not give the size of that facet correlation, and the Big Five domain that contains orderliness, conscientiousness, was not among the two strongest correlates the abstract names, openness and neuroticism. So the sign of the facet matches the viral claim, and the evidence for it is a population average across many studies with an unreported size. It is not evidence that a messy desk is a sign of anything in a single person. The page on IQ and personality goes through the traits one at a time.

5 Is Talking to Yourself a Sign of High IQ? What Self-Talk Experiments Show

The self-talk experiments show that speaking aloud can help on a task when people are told to do it, and none of them measured IQ or asked who talks to themselves more. The best known laboratory result comes from Gary Lupyan and Daniel Swingley, who asked participants to search for common objects, sometimes while speaking the name of the target aloud (Lupyan and Swingley 2012). Speaking facilitated search, particularly when the name was strongly associated with the visual target, and as the mismatch between the name and the target grew, speaking began to impair performance. The authors presented this as evidence that words can modulate ongoing visual processing, not as a trait of smart people.

A 2023 study in Consciousness and Cognition moved the question to memory. Guo and Dobkins asked 103 young adults, with a mean age of 20.21 years, to complete a visual-spatial working memory task while talking out loud to themselves as much as possible (Guo and Dobkins 2023). Participants did better on trials in which they produced more private speech. Because that pattern could be driven by who talks more, the authors also compared the private speech condition with a quiet condition, and performance was better with private speech. Task difficulty, varied through how easily the images could be labeled, did not change the benefit, and participants who used more private speech during the task, and those who reported more everyday use of self-management private speech, showed the biggest benefits.

Two features of these designs matter for the viral claim. The instruction to talk aloud was assigned by the experimenters, which supports the statement that speaking helped on that task in that sample. It says nothing about adults who talk to themselves on their own, who may differ from other adults in ways nobody measured. And the tasks were a visual search and a visual-spatial working memory game, so the results speak to the performance of a skill, with working memory (Gwm) as the closest CHC ability. The page on IQ and memory describes how that ability relates to a general score, and the page on a working memory test for adults describes how a normed task measures it.

What would a test of the viral claim look like? It would measure habitual self-talk with a validated questionnaire or a diary, measure IQ with a normed instrument, and recruit a sample large enough to estimate the link with a confidence interval. None of the studies above did that, and this page did not locate one. That absence is informative in its own right: the lists treat a pleasant, plausible habit as a finding, when the work that exists asks a different question, namely whether using private speech helps with a task. If you talk to yourself while you work, the experiments suggest it may be a useful tool, and the same experiments give no reason to read it as a sign of anything about your score.

6 Do Smart People Overthink? Worry, Rumination and Intelligence

Overthinking is not one thing in the studies: verbal ability went with worry and rumination in one student sample, reflective pondering but not brooding went with higher scores in a twin study, and the links to distress shrank once overlap was controlled. The lay word covers several processes that psychologists measure separately, and the two studies below show why the separation matters. Neither study diagnoses anyone, and both describe group averages in specific samples.

Alexander Penney and colleagues surveyed 126 undergraduates and measured symptoms of generalized anxiety, depression and social anxiety, the cognitive processes of worry, rumination and post-event processing, and verbal and nonverbal intelligence (Penney and colleagues 2015). Verbal intelligence had positive relationships with generalized anxiety and depression symptoms once test anxiety and state negative affect were taken into account, but those relationships became non-significant when overlapping variance was controlled. Verbal intelligence remained a unique positive predictor of the severity of worry and rumination, and nonverbal intelligence was a unique negative predictor of post-event processing. So even inside one small sample the sign of the link depends on which process and which kind of ability one looks at.

The second study is larger and uses a better-known design. Du Pont and colleagues analyzed 751 people from the Colorado Longitudinal Twin Study, who completed the Ruminative Response Scale, depression measures, verbal and performance intelligence tasks at age 16 and Raven's Advanced Progressive Matrices at age 23 (du Pont and colleagues 2020). After controlling for overlap with depression, reflective pondering was positively associated with all the intelligence measures, whereas brooding was not associated with intelligence. The authors concluded that negative associations between rumination and intelligence are attributable to shared variance with depression. That is a statement about statistical overlap in one cohort, and it does not say that thinking harder makes anyone more intelligent or that intelligence makes anyone brood.

Taken together the two studies support a careful sentence: reflective pondering goes with somewhat higher scores in a twin cohort, while brooding does not. They do not support the sentence on the lists, "smart people overthink everything," and they do not support treating anxiety or low mood as a badge of brilliance, a framing that would also be unkind to people who struggle with them. The relation between intelligence and distress is covered on the pages about IQ and depression, anxiety and IQ and the wider hub on IQ and mental health, which separate risk, symptoms and ability and carry the cautions this short section cannot.

7 Do Smart People Get Bored Easily? Boredom Proneness and Ability

The boredom studies that exist did not link boredom to IQ: the large survey measured self-control, and the one study of talented adolescents found boredom levels similar to the general adolescent population. Boredom proneness is a stable tendency to find situations dull, and it is measured with questionnaires, not with ability tests. The claim that smart people get bored easily usually rests on a plausible argument, that a quick mind runs out of challenge sooner, and not on a study that tested it with an intelligence score.

The largest study in this audit is a survey. Isacescu, Struk and Danckert surveyed 1,928 undergraduates on boredom proneness, self-control, mind wandering, depression and aggression (Isacescu and colleagues 2017). Self-control was a strong negative predictor of boredom proneness, and when age and self-control were controlled, the relationships between boredom proneness and the other measures dropped by large amounts. The authors concluded that individual differences in self-control account for most of the variance in the links between boredom, cognition and affect. An intelligence test is not among the measures the abstract lists. The study therefore says that people with lower self-control report being bored more easily, and it does not say which way intelligence runs.

The one study of an ability-selected group is small and mixed. Vuyk, Montania and Barrios studied adolescents with exceptional mathematical talent in a talent development program in Paraguay: 54 students completed boredom and attitude questionnaires and 50 took part in focus groups (Vuyk and colleagues 2024). Boredom in this group was similar to the general population of adolescents. Differences existed in some items and subscales: the students tended to become bored more quickly but had an easier time sparking interest in activities. The focus groups named waiting for other people's slower pace, limited choices, lack of novelty and insufficient intellectual challenge among the contributing factors. That is a fair description of a plausible mechanism, collected from the students themselves, in one program in one country, with talent defined by the program and not by an IQ test.

Taken together, the sources support a statement about fit. Boredom grows when a task is too easy, too repetitive or without meaning, and that can happen at any level of ability. A person of high ability in a classroom paced for the average can meet it more often, and a person of average ability in a task that is too easy for them can meet it too. The second half of that sentence is the part the lists leave out. The page on gifted adults separates what a strong score can mean from the traits that circulate with the label, and the page on how IQ scores are normed explains the comparison with other adults that a score rests on and that a boredom story leaves out.

8 Night Owls, Short Sleepers and Left-Handers: Three Habits With Their Own Evidence Pages

Staying up late, sleeping little and being left-handed each have a dedicated evidence page on this site, and in each case the viral claim is larger than anything the measured differences support. This audit does not repeat those pages. It states what the original claims rested on and where to read the full record.

The night owl claim has a named origin. Kanazawa and Perina proposed the Savanna-IQ Interaction Hypothesis, the idea that more intelligent individuals are more likely to acquire and espouse evolutionarily novel values and preferences, while general intelligence has no effect on evolutionarily familiar ones (Kanazawa and Perina 2009). They reasoned that nocturnal activity was probably rare in the ancestral environment, predicted that more intelligent people would be more nocturnal, and reported that an analysis of the National Longitudinal Study of Adolescent Health confirmed the prediction. The hypothesis is a theory about novelty, and the night owl result is one test of it in one survey. The page on night owls and IQ traces how that result and later headlines relate to the size of the effect in larger and more recent studies, and it separates the claim that evening types score higher from the claim that staying up late raises or signals intelligence.

Short sleep belongs to a different family of claims, because a state effect and a trait effect get confused. A short night before a test lowers attention and speed on that day, which says something about the score and nothing about the person's ability. Whether people who habitually sleep little have higher ability is a separate and much weaker question, and this page located no study that supports it. The page on sleep and IQ splits the state question from the trait question and walks through studies on both sides, including ones that found nothing.

Left-handedness shows how a measurement choice can create a story. Studies of handedness and IQ define a left-hander in several ways: by writing hand, by a questionnaire about a list of tasks, by the speed or accuracy of each hand, or by an observer's judgment, so results are hard to compare. The page on left-handedness and IQ summarizes the meta-analytic evidence and concludes that the difference is too small to matter in either direction, and that no group result can say anything about the score of one left-handed person.

These three show a pattern that recurs through the audit: when a habit is easy to observe and describe, a single positive result, such as a night owl advantage in one survey, travels as a rule, while the larger and later studies that shrink it travel poorly.

9 Does Handwriting Say Anything About IQ? What Studies of Handwriting Measure

The handwriting studies this page located measure children and show that legibility and speed depend on motor, spelling and attention skills, and none of them relates handwriting quality to an IQ score in a general adult sample. The claim that smart people have bad handwriting is common in lists, and it is the one with the thinnest sourcing, so the honest section is short on findings and long on what a valid test would need.

The most relevant recent study is not about intelligence. Downing and Caravolas gave a group-administered battery to children in three school years, 293 in Year 3, 291 in Year 4 and 283 in Year 5, and modeled how spelling, graphomotor skill and selective attention relate to handwriting (Downing and Caravolas 2023). The three skills together explained a moderate amount of the variance in legibility, with R squared between 0.37 and 0.42, and in fluency, with R squared between 0.41 and 0.58. Graphomotor skill accounted for a relatively larger share of legibility than spelling did, spelling contributed relatively more to fluency, and selective attention predicted fluency only. The authors conclude that legibility and fluency are separable and complex skills, each related to different abilities.

That finding changes what a viral claim would have to mean. If handwriting reflects fine motor control, spelling and attention, then a link between handwriting and IQ would have to run through those skills, and no single direction is obvious. A person can have fast, precise motor control and a modest score on reasoning tasks, or the reverse. Handwriting is also a skill that changes with practice, with schooling, and with how much a person writes by hand today, none of which is intelligence. Hurried notes by a busy adult may look different from careful notes by the same adult.

A valid study of the claim would need four things. It would measure legibility by blind ratings of a standard passage written at a standard speed, and measure speed separately. It would measure intelligence with a normed test in a general adult sample, not in students at one institution. It would control for age, handedness, writing practice and device use. And it would report the correlation with an interval, so that a reader could judge whether the number was distinguishable from zero. This page did not locate a peer-reviewed study that does all four, and it left out two small figures that circulate in blog posts about handwriting, because it could not open the studies they come from.

Two related points avoid the opposite mistake. Poor handwriting can have a clinical or developmental explanation, and giftedness and a learning or motor difference can occur together, as the page on twice-exceptional people and the page on dyslexia and IQ describe. And none of that makes handwriting a sign of anything for an adult reader looking at their own notes. The fair summary is that the lists did not get this one from a study of intelligence.

10 Which Personality Traits Do Have Meta-Analytic Support, and How Small Are They?

The best evidence on personality and intelligence points to traits of thinking style, intellectual engagement and unconventionality, and not to desks, bedtimes or vocabulary for swear words, and even those links are modest group averages. The most comprehensive source is the meta-analysis by Jeromy Anglim and colleagues in Psychological Bulletin, which pooled 272 studies with 162,636 participants and examined correlations of general, fluid and crystallized intelligence with personality at the level of domains, facets and individual questionnaire items (Anglim and colleagues 2022). It is the right place to look for whether a quirk might have a real basis, because it covers four major personality inventories and does not rest on one sample.

The headline results are openness, with a population correlation of 0.20, and neuroticism, with a population correlation of minus 0.09, as the strongest Big Five correlates of intelligence. Openness correlated more with crystallized than with fluid intelligence, a distinction explained on the page on fluid versus crystallized intelligence. At the facet level, traits related to intellectual engagement and unconventionality were more strongly related to intelligence than other openness facets, while sociability and orderliness were negatively correlated with it. The authors also report that facets explained more than twice the variance that domains did, which is a reminder that a trait label such as "conscientiousness" hides facets that point in different directions.

This is the nearest the literature comes to the viral lists, so each habit can be placed against it with care. "Quirky" in the lists sounds like unconventionality, and unconventionality is one of the facets with a positive link to intelligence, although the abstract does not give its size, and a questionnaire facet is not a habit such as a messy desk. "Messy" sounds like low orderliness, and orderliness had a negative facet correlation, again with an unreported size in the abstract. "Swears" overlaps with low agreeableness and high openness in the fluency studies, and the personality meta-analysis names openness as a leading correlate. None of these overlaps converts a habit into a sign, because the unit in each case is a population average, and because the link between a trait and a behavior is itself loose.

The numbers set the scale. A correlation of 0.20 is about 4 percent of shared variance by our arithmetic, and minus 0.09 is under 1 percent. Even the best supported personality links therefore leave nearly all of the variation in intelligence to other things, which is why the page on IQ and personality frames them as tendencies, and why the page on average IQ by personality type treats type labels with caution. The practical rule is simple. If a trait list claims that a long list of small habits identifies a high scorer, count how many of those habits have any measured link and how large each is. By that test the list in this audit does poorly, while the traits with real support, such as intellectual engagement, do not make a catchy list. The sibling page on empathy and IQ applies the same audit to another trait that people assume goes with ability.

11 Why Do These Lists Keep Spreading Without Better Evidence?

These lists spread because each habit is easy to recognize in yourself, each claim has a one-sentence study to point to, and the later studies that shrink the claim never reach the same audience. Four mechanisms show up in the audit, and each has a concrete example from the sources above.

The first is the pull of a flattering and familiar trait. A habit that many people have and that feels a little embarrassing, such as swearing, clutter or lying awake, becomes pleasant to hear about when it is tied to ability. The page on the signs of high intelligence makes the point that a vague, appealing trait lets almost anyone see themselves in it, and that a trait list cannot establish adult giftedness. The second is a reduction from a study to a headline. The fluency study asked whether swearers have small vocabularies, and the fact check shows what happened when a post turned it into advice about befriending swearers, with the author declining to endorse that reading (Lead Stories 2019).

The third mechanism is the single small study. The messy desk effect was reported from groups of about 20 to 25, which is small enough for chance to produce a striking difference, and the replication with about 50 per group did not find one. The fourth is that the correction is quieter than the claim. In our judgment, a replication report such as the messy desk one rarely draws the attention that the original headline did, so the claim survives in the lists while the correction stays in the journal. The distortion happens downstream, in the step from a paper to a list, and the original papers are cautious.

A short set of questions, taken from the audit, handles most claims of the form "smart people do X."

The handwriting claim has no study to put through these questions at all, and the habit with the most to put through them is overthinking, which has two studies with intelligence tests, one of them a twin cohort of 751. Even there, the honest reading is conditional and specific. A reader can apply the four questions to any list, including this one, and the sources section gives the papers to check.

12 What to Make of a Quirk, and How to Read Any Score, Including the Standards

A quirk cannot tell you your IQ, and no habit should lead you to read a score higher or lower than the test supports, because a score is evidence for a purpose, with an error and a comparison group. The Standards for Educational and Psychological Testing (AERA, APA and NCME, 2014), the joint publication of the American Educational Research Association, the American Psychological Association and the National Council on Measurement in Education, which we opened as an open access listing on October 20, 2026 (the Standards' own site), frames the question a trait list cannot answer. Whether a score supports a particular interpretation is a matter of evidence for that use, together with the score's reliability and error and the group it is compared against. A habit is not evidence of that kind, and a population correlation of 0.20 does not replace it.

The APA Guidelines for Psychological Assessment and Evaluation, approved by the APA Council of Representatives in March 2020 and read on October 20, 2026, point the same way (APA 2020). Guideline 5 asks psychologists who provide testing to apply psychometric principles and measurement science, including reliability and measurement error and the effects of context, setting and purpose. Guideline 7 asks them to use multiple sources of relevant and reliable information, and its rationale states that performance on a test is one piece of an assessment. The guidelines are written for professionals who give and interpret tests, but their logic helps any reader: a number is not an identity, and a habit is not a number.

If you want to know something about your own abilities, measure them. A normed cognitive test reports where your performance sits relative to other adults on defined abilities, and a good one shows its margin of error. ACIS is one such option, and it is an online, unsupervised test and not a clinical or diagnostic instrument. It reports a Full Scale IQ and six index scores on the standard scale with a mean of 100 and a standard deviation of 15, covering verbal comprehension (VCI), fluid reasoning (FRI), quantitative reasoning (QRI), visual spatial (VSI), working memory (WMI) and processing speed (PSI), along with percentiles and a 95 percent confidence interval. Scaled subtest scores run from 1 to 19. Adult norms cover ages 16 to 90, and the test is in English only. It is not designed for hiring decisions, school accommodations or admission to high IQ societies. The forms and one time prices we read on October 20, 2026 are Quick at 15 dollars (6 subtests, about 45 minutes), Optimized at 30 dollars (13 subtests, about 110 minutes) and Full Scale at 50 dollars (all 20 subtests, about 175 minutes), with a free trial that needs no card. Prices can change, and the documentation is on the ACIS technical manual.

Whatever instrument you choose, read the result with its interval and its conditions. The page on how IQ scores are normed explains the comparison behind a score, and the page on how accurate online IQ tests are says what an unsupervised test can and cannot support. If a decision with real consequences depends on a result, a professional assessment that follows those guidelines is the better route. The other pages in this series, on obesity and IQ and on math ability and IQ, apply the same method to other claims.

13 Sources Behind This Page

Every journal article below was checked against its DOI record in Crossref on October 20, 2026, and each figure used on this page was read in the article's abstract or in a paper that describes the study on that date.

• American Educational Research Association, American Psychological Association, and National Council on Measurement in Education. Standards for Educational and Psychological Testing. 2014 edition, page opened October 20, 2026.
• American Psychological Association, APA Task Force on Psychological Assessment and Evaluation Guidelines. APA Guidelines for Psychological Assessment and Evaluation. Approved by the APA Council of Representatives in March 2020, read October 20, 2026.
• Anglim, J., Dunlop, P., Wee, S., Horwood, S., Wood, J., and Marty, A. Personality and intelligence: A meta-analysis. Psychological Bulletin, 2022, volume 148, issues 5 and 6, pages 301 to 336.
• Downing, C., and Caravolas, M. Handwriting legibility and fluency and their patterns of concurrent relations with spelling, graphomotor, and selective attention skills. Journal of Experimental Child Psychology, 2023, volume 236, article 105756.
• du Pont, A., Karbin, Z., Rhee, S., Corley, R., Hewitt, J., and Friedman, N. Differential associations between rumination and intelligence subtypes. Intelligence, 2020, volume 78, article 101420.
• Guo, X., and Dobkins, K. Private speech improves cognitive performance in young adults. Consciousness and Cognition, 2023, volume 116, article 103585.
• Isacescu, J., Struk, A., and Danckert, J. Cognitive and affective predictors of boredom proneness. Cognition and Emotion, 2017, volume 31, issue 8, pages 1741 to 1748.
• Jay, K., and Jay, T. Taboo word fluency and knowledge of slurs and general pejoratives: deconstructing the poverty-of-vocabulary myth. Language Sciences, 2015, volume 52, pages 251 to 259.
• Kanazawa, S., and Perina, K. Why night owls are more intelligent. Personality and Individual Differences, 2009, volume 47, issue 7, pages 685 to 690.
• Lead Stories (Alan Duke). Hoax alert on the claim that psychologists urge people to befriend those who swear a lot. Published July 31, 2019 and updated August 1, 2019, page opened October 20, 2026.
• Lupyan, G., and Swingley, D. Self-directed speech affects visual search performance. Quarterly Journal of Experimental Psychology, 2012, volume 65, issue 6, pages 1068 to 1085.
• Manzi, A., Durmysheva, Y., Pinegar, S., Rogers, A., and Ramos, J. Workspace disorder does not influence creativity and executive functions. Frontiers in Psychology, 2019, volume 9, article 2662.
• Penney, A., Miedema, V., and Mazmanian, D. Intelligence and emotional disorders: Is the worrying and ruminating mind a more intelligent mind? Personality and Individual Differences, 2015, volume 74, pages 90 to 93.
• Reiman, A., and Earleywine, M. Swear word fluency, verbal fluency, vocabulary, personality, and drug involvement. Journal of Individual Differences, 2023, volume 44, issue 1, pages 37 to 46.
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