Psychological measurement — or psychometrics — is the science of quantifying mental capabilities. From clinical IQ batteries to specialized cognitive screens, every score depends on construction choices, reliability evidence, and validity studies. This hub indexes our research-grade coverage of how cognitive tests are built, evaluated, and interpreted.
If you are looking for the technical statistical methods behind these tests, see the companion hub on statistical methods in psychology. For broader theoretical coverage of intelligence as a construct, see cognitive abilities and intelligence research.
In this hub
- Interpreting IQ scores
- The Wechsler family: WAIS and WISC
- Stanford-Binet, Raven’s Matrices, and other major batteries
- Cogn-IQ instruments (JCTI, JCCES, JCFS, JCWS, IAW)
- Specialized scales and screening tools
- Online testing, adaptive testing, and item monitoring
- Validity, criticism, and the Flynn effect
- SAT and other proxy measures of cognitive ability
- Foundations of psychometrics
Interpreting IQ scores
Test scores are only as useful as the framework you use to read them. These articles cover what scores mean, where they sit on the population distribution, and the conditions under which a single score should and should not drive decisions.
- How to interpret IQ test results — what subtest scatter, confidence intervals, and percentile ranks actually tell you.
- The IQ bell curve: how scores are distributed — the normal distribution applied to cognitive ability.
- What an IQ of 130, 140, or 150 actually means — rarity, measurement precision, and the limits of high-end interpretation.
- High IQ ranges: percentiles and meaning — gifted, highly gifted, and exceptionally gifted bands.
- Average IQ by age across the lifespan — age-normed scores and what they reveal about cognitive aging.
- IQ test anxiety: how stress affects your score — state effects on a supposedly trait measure.
- What is Mensa? Membership and testing — how the 98th-percentile threshold gets applied in practice.
- How to test your child’s IQ — clinical vs. school-administered options for parents.
The Wechsler family: WAIS and WISC
The Wechsler scales — the WAIS for adults and the WISC for children — remain the most widely used clinical IQ instruments worldwide. We cover their history, structure, and the most recent revisions in detail.
- History of the WAIS: from Wechsler-Bellevue to WAIS-V — how the modern adult battery evolved across eight decades.
- What the WAIS-IV measures: subtests explained — index by index, what each task taps.
- WAIS-IV vs. WAIS-V: what changed — subtest revisions, norms, and clinical implications of the 2024 release.
- WAIS-IV CHC factor structure in older adults — how the four-factor model holds up at age 65+.
- Validity of WISC-V strengths and weaknesses profiles — the evidence on subtest-level interpretation.
- WISC-V short-form IQ estimation — abbreviated assessments for triage and screening.
- CHC cognitive abilities and writing achievement — how the Cattell-Horn-Carroll factor model predicts academic skills.
Stanford-Binet, Raven’s Matrices, and other major batteries
Several other instruments — with their own measurement traditions distinct from the Wechsler family — play central roles in cognitive assessment.
- Stanford-Binet vs. WAIS in intellectual disability — how the two oldest individually administered IQ traditions handle floor effects and severe impairment.
- Raven’s Progressive Matrices: the culture-fair IQ test — the canonical nonverbal reasoning measure.
- NIH Toolbox: cognitive change in intellectual disability — sensitivity to change in clinical populations.
- Cognitive measures of reasoning and language — how different batteries operationalize the same constructs.
Cogn-IQ instruments (JCTI, JCCES, JCFS, JCWS, IAW)
The Cogn-IQ family of cognitive tests — developed at cogn-iq.org by our research team — provides freely accessible, psychometrically validated instruments covering fluid, crystallized, verbal, and nonverbal abilities.
- JCTI: validity and reliability — the Jouve-Cerebrals Test of Induction, a Raven-style fluid-reasoning measure.
- Age-based reliability of the JCTI — precision profiles across the lifespan.
- JCCES: reliability of the Crystallized Educational Scale — vocabulary, math, and general-knowledge crystallized assessment.
- JCFS: assessing nonverbal intelligence — figural sequences calibrated for fluid reasoning.
- JCWS: a verbal abilities test — word-similarities measure of crystallized verbal ability.
- IAW: assessing verbal intelligence — analogies-based verbal reasoning instrument.
- Validity and reliability of the CCAT — the original Cerebrals Cognitive Abilities Test, the three-subtest crystallized battery later revised into the JCCES.
Specialized scales and screening tools
Not every cognitive measurement is a full IQ battery. Brief scales and self-administered screens fill specific assessment niches.
- AMES: self-administered cognitive screening — rapid triage for cognitive impairment.
- NCS-6: a brief Need for Cognition scale — six-item measure of intellectual engagement.
- Overclaiming: why people claim knowledge they don’t have — a check on self-report knowledge measures.
- Nonmemory-based performance validity tests — detecting suboptimal effort in cognitive testing.
Online testing, adaptive testing, and item monitoring
Modern testing increasingly happens online and adaptively. These articles cover the methods that make remote, computer-administered cognitive assessment psychometrically defensible.
- Online IQ tests vs. professional assessments — what online testing can and cannot replicate.
- Item response theory: how modern tests work — the IRT framework underlying most modern cognitive batteries.
- Computerized adaptive testing explained — how modern tests adapt item difficulty to the test-taker.
- Advanced computerized adaptive testing techniques — item selection, exposure control, and stopping rules.
- Sequential GLR tests for online item monitoring — detecting compromised items in operational testing.
Validity, criticism, and the Flynn effect
Cognitive testing is one of the most empirically scrutinized areas in psychology. These articles address the major validity questions and population-level changes in test scores over time.
- Do IQ tests measure what they claim? — common criticisms answered with the validity evidence.
- The Flynn effect: are humans getting smarter or dumber? — a century of rising and now reversing IQ scores.
- Trends in the Flynn effect over time — cohort-level analysis of the slowdown and reversal.
SAT and other proxy measures of cognitive ability
High-stakes admissions tests like the SAT load heavily on general cognitive ability. We examine how closely these test scores track IQ and what that correlation means.
- SAT scores and IQ: how closely are they correlated? — the meta-analytic evidence on SAT-g loading.
- SAT scores and general cognitive ability — factor-analytic decomposition of the SAT.
- Self-control strategies and SAT outcomes — non-cognitive predictors of test performance.
Foundations of psychometrics
The science of measuring psychological constructs has its own conceptual foundations. These articles step back to examine the field as a discipline.
- Psychometrics: the science of psychological measurement — what the field is, what it does, and why it matters.
- Bridging psychology and psychometrics — why theory-of-the-construct and theory-of-the-test must align.