How to read this timeline
Each era marks a shift in how the field thought about measuring intelligence — from sensorimotor reaction-time studies, through the WWI mass-testing programs and the WAIS, to CHC theory and today's computer-adaptive batteries.
Two kinds of entry113 total
57Interactive
A fully playable web version you can take on this site.
56Reference
An archive page with the original source book on Internet Archive.
TEN STRANDS · 146 YEARS
The family lines running through the timeline
Eras show when a test appeared; strands show what it descends from. Each dot is a test. Hover a dot for its name, click it to open the page, or click a strand to filter the timeline below.
Strand assignments are editorial: some tests straddle two lines (Raven's matrices are both non-verbal and a measure of g), and each sits in the one it most directly descends from.
NINE IDEAS THAT CHANGED TESTING
From mental age to item response theory
Mental ageBinet and Simon ordered tasks by the age at which typical children passed them, so a child's performance could be stated as an age level rather than a rank in class.
ERA 1 · 1880–1919
Pioneer Era
The first systematic attempts to measure mental ability. Wundt opened the first psychology laboratory in 1879; the next forty years gave us reaction-time studies, Cattell's mental tests, the Binet-Simon scale (which introduced "mental age") and the WWI Army Alpha that turned IQ testing into a mass enterprise.
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1880Wundt's Reaction Time StudiesInteractiveWilhelm WundtLABORATORY ORIGINSThe earliest systematic experimental study of mental speed, from Wundt's founding psychology laboratory in Leipzig.1884Galton's Anthropometric Laboratory MeasuresInteractiveSir Francis GaltonLABORATORY ORIGINSThe earliest systematic attempt to measure individual differences in mental capacity, run at the 1884 International Health Exhibition in London.1890Cattell's Mental Tests and MeasurementsInteractiveJames McKeen CattellLABORATORY ORIGINSThe paper that coined the phrase "mental test": ten sensorimotor tasks, from reaction time to memory span.1895Binet-Henri Mental TestsInteractiveAlfred Binet & Victor HenriBINET LINEThe proto-Binet test, ten years before the famous 1905 Binet-Simon scale, proposing ten mental faculties to measure.1895Bourdon Cancellation TestInteractiveBenjamin BourdonLABORATORY ORIGINSOne of the earliest attention and processing-speed tests: scan rows of letters and cancel a target letter as fast as possible.1895Kraepelin Continuous Arithmetic TestInteractiveEmil KraepelinLABORATORY ORIGINSA test of sustained mental work: long series of simple additions under time pressure.1897Ebbinghaus Completion TestInteractiveHermann EbbinghausLABORATORY ORIGINSThe first proposed intelligence test based on a single cognitive principle.1904Spearman's General Intelligence (g)InteractiveCharles SpearmanFACTOR & THEORY-BASEDThe conceptual foundation of modern psychometrics: all cognitive abilities share a common factor, g.1905Binet-Simon ScaleInteractiveAlfred Binet & Théodore SimonBINET LINEThirty tasks in order of difficulty, built for a French ministerial commission: the first practical intelligence scale.1906Norsworthy Mental Tests for Subnormal ChildrenInteractiveNaomi NorsworthyLABORATORY ORIGINSThe first US-developed standardized intelligence test.1910Goddard's Binet-Simon TranslationInteractiveHenry H. GoddardBINET LINEThe English-language adaptation that introduced Binet's intelligence testing to American psychology.1913Pyle's Examination of Mental AbilitiesInteractiveWilliam H. PyleGROUP SCHOOL TESTSA group-administered school test that predates both the Army Alpha and the Otis Group Intelligence Scale.1914Healy Pictorial Completion TestInteractiveWilliam HealyNON-VERBAL & PERFORMANCEAn early non-verbal test: identify what is missing from each picture.1914Knox Cube Imitation TestInteractiveHoward A. KnoxNON-VERBAL & PERFORMANCEA non-verbal test designed to screen immigrants at Ellis Island: imitate a tapped sequence on four cubes.1914Whipple's Manual of Mental and Physical TestsInteractiveGuy Montrose WhippleLABORATORY ORIGINSThe standard American compendium of cognitive testing methods before WWI.1915Porteus Maze TestInteractiveStanley D. PorteusNON-VERBAL & PERFORMANCEA series of printed paper mazes of increasing difficulty, used as a non-verbal test.1915Yerkes-Bridges Point Scale for Measuring Mental AbilityInteractiveRobert M. Yerkes, James W. Bridges & Rose S. HardwickBINET LINEA pre-WWI Binet revision that gave each item a point value, anticipating modern test design.1916Stanford-Binet (Stanford Revision)InteractiveLewis M. TermanBINET LINETerman's American revision of Binet, which multiplied Stern's mental quotient by 100 and made "IQ" a single number.1917Pintner-Paterson Scale of Performance TestsInteractiveRudolf Pintner & Donald G. PatersonNON-VERBAL & PERFORMANCEThe first major non-verbal cognitive test battery.1918Army AlphaInteractiveRobert M. Yerkes & the Army Division of PsychologyMILITARY TESTINGThe WWI written group test given to about 1.7 million recruits. All 200 items of Form 5 are playable.1918Army Alpha Form 6InteractiveYoakum & YerkesMILITARY TESTINGOne of five parallel forms of the 1918 Army Alpha; its Test 1 script and all 16 Test 3 items are rebuilt here.1918Army Alpha Forms 7, 8, 9InteractiveYoakum & YerkesMILITARY TESTINGThe remaining three parallel forms; all 48 of their Test 3 items are rebuilt here.1918Army BetaInteractiveRobert M. Yerkes & the Army Division of PsychologyMILITARY TESTINGThe non-verbal companion to the Alpha, given by pantomime to illiterate and non-English-speaking recruits.1918Manual of the Mental Examination of AliensInteractiveU.S. Public Health ServiceNON-VERBAL & PERFORMANCEThe official protocol used at Ellis Island and other ports of entry to assess arriving immigrants.1918Otis Group Intelligence ScaleInteractiveArthur S. OtisGROUP SCHOOL TESTSThe first widely used group-administered intelligence test for schools.1918Army Individual ExaminationInteractiveArmy Division of Psychology (Vineland committee incl. F. L. Wells)MILITARY TESTINGOne-to-one WWI examination (Stanford-Binet, Point Scale, ten-test Performance Scale) for recruits the group tests could not rate.1919Seashore Measures of Musical TalentsInteractiveCarl E. SeashoreLABORATORY ORIGINSThe first standardized test of musical aptitude, on five phonograph records: pitch, intensity, time, consonance and tonal memory.
ERA 2 · 1920–1944
Mass-Testing Era
After WWI proved tests could be scaled, the 1920s and 1930s saw an explosion of school, immigration and industrial tests. Wechsler invented adult IQ, and the SAT, MMPI and Raven's Matrices all appeared during this period.
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1920Dearborn Group Tests of IntelligenceInteractiveWalter F. DearbornGROUP SCHOOL TESTSA Harvard-developed group test for school use, in Series A, B and C.1920National Intelligence TestsInteractiveHaggerty, Terman, Thorndike, Whipple & YerkesGROUP SCHOOL TESTSThe school version of the Army Alpha.1920Pintner Non-Language Mental TestInteractiveRudolf PintnerNON-VERBAL & PERFORMANCEA group non-verbal test that brought language-free assessment into schools.1921Burt's Mental and Scholastic TestsInteractiveSir Cyril BurtGROUP SCHOOL TESTSThe standard British intelligence test from the 1920s through the 1950s.1921Haggerty Intelligence Examination Delta 2InteractiveMelvin E. HaggertyGROUP SCHOOL TESTSA group intelligence test for grades 3 through 12.1921Pressey X-O Test of Emotion and PersonalityInteractiveSidney L. PresseyPERSONALITY & MOODOne of the first standardized measures of attitudes and personality.1921Psychological Examining in the United States ArmyReferenceRobert M. Yerkes (editor)MILITARY TESTINGThe definitive 890-page compendium of the WWI Army testing program.1921Rorschach Inkblot TestReferenceHermann RorschachPERSONALITY & MOODTen inkblot cards recognised worldwide — the most famous psychological test ever created.1922Trabue Language ScaleInteractiveMarion R. TrabueGROUP SCHOOL TESTSA group test of verbal completion: "The cat ___ the mouse."1923Kohs Block-Design TestReferenceS.C. KohsNON-VERBAL & PERFORMANCEReproduce printed designs by arranging coloured wooden blocks.1923Pintner-Cunningham Primary Mental TestInteractiveRudolf Pintner & Bess V. CunninghamGROUP SCHOOL TESTSA picture-based group intelligence test for kindergarten and grades 1–2, with instructions read aloud.1923Stanford Achievement TestInteractiveTruman L. Kelley, Giles M. Ruch & Lewis M. TermanADMISSIONS & ACHIEVEMENTThe first American achievement test from a unified, theoretically grounded testing program.1925American Council on Education Psychological ExaminationInteractiveL.L. Thurstone & T.G. ThurstoneADMISSIONS & ACHIEVEMENTThe first national college-admissions intelligence test in the United States.1925Detroit First-Grade Intelligence TestInteractiveAnna J. EngelGROUP SCHOOL TESTSA picture-based group test for first-graders aged 5–7.1925Thorndike CAVD Intelligence ScaleInteractiveEdward L. ThorndikeGROUP SCHOOL TESTSFour task types: Completion, Arithmetic, Vocabulary and following Directions.1926Goodenough Draw-A-Man TestReferenceFlorence L. GoodenoughNON-VERBAL & PERFORMANCEDraw a picture of a man, scored on a 51-point checklist.1926Scholastic Aptitude Test (SAT)InteractiveCarl C. BrighamADMISSIONS & ACHIEVEMENTThe most consequential standardized test in American education, adapted from Army Alpha items.1927Kuhlmann-Anderson TestsInteractiveF. Kuhlmann & Rose G. AndersonGROUP SCHOOL TESTSOne of the first batteries to span grades 1 through 12 with grade-specific subtests.1927Strong Vocational Interest BlankInteractiveEdward K. Strong Jr.ADMISSIONS & ACHIEVEMENTThe first major standardized interest inventory and the foundation of modern career assessment.1928MCAT (Medical College Admission Test - Original 1928)ReferenceF.A. Moss / Association of American Medical CollegesADMISSIONS & ACHIEVEMENTA 3-hour, 6-section test created to address high medical school dropout rates.1931Henmon-Nelson Tests of Mental AbilityInteractiveV.A.C. Henmon & M.J. NelsonGROUP SCHOOL TESTSA group test for grades 3–12 and college freshmen, known for its tight time pressure.1933Bayley Scales of Mental and Motor DevelopmentReferenceNancy BayleyCLINICAL & NEUROPSYCHThe foundational instrument for assessing infant and toddler cognitive development.1935Iowa Tests of Basic Skills (Early Forms)InteractiveE.F. Lindquist & H.A. GreeneADMISSIONS & ACHIEVEMENTThe most influential American achievement-and-aptitude battery ever produced.1935Stroop Color-Word TestInteractiveJohn Ridley StroopCLINICAL & NEUROPSYCHName the ink colour, not the word — the single most-cited cognitive test in history.1935Thematic Apperception Test (TAT)ReferenceHenry A. Murray & Christiana D. MorganPERSONALITY & MOODA projective personality test using ambiguous picture cards.1935Vineland Social Maturity ScaleReferenceEdgar A. DollCLINICAL & NEUROPSYCHA scale of adaptive functioning rather than a traditional IQ test.1936California Test of Mental MaturityInteractiveElizabeth T. Sullivan, Willis W. Clark & Ernest W. TiegsGROUP SCHOOL TESTSVerbal, non-verbal and quantitative subtests in one group test for K–12.1936Otis Quick-Scoring Mental Ability TestsInteractiveArthur S. OtisGROUP SCHOOL TESTSA machine-scoreable, 30-minute redesign of the 1918 Group Intelligence Scale.1936Raven's Progressive MatricesReferenceJohn C. RavenNON-VERBAL & PERFORMANCEIntroduced the visual matrix-completion format, now the most-used non-verbal intelligence test in the world.1937Stanford-Binet 1937 (Terman-Merrill Revision)ReferenceLewis M. Terman & Maud A. MerrillBINET LINEThe revision that dominated US individual intelligence testing until the late 1950s.1938Bender Visual-Motor Gestalt TestReferenceLauretta BenderCLINICAL & NEUROPSYCHReproduce nine geometric figures adapted from gestalt psychology.1938Thurstone Primary Mental AbilitiesInteractiveL.L. Thurstone & T.G. ThurstoneFACTOR & THEORY-BASEDA 7-factor model: Verbal, Number, Spatial, Memory, Word Fluency, Perceptual Speed and Reasoning.1939Wechsler-Bellevue Intelligence ScaleReferenceDavid WechslerWECHSLER LINEIntroduced the deviation IQ and the verbal–performance split.1941Rey-Osterrieth Complex Figure TestReferenceAndré Rey & Paul-Alexandre OsterriethCLINICAL & NEUROPSYCHCopy a complex geometric figure, then reproduce it from memory after a delay.1941SRA Primary Mental Abilities TestInteractiveL.L. Thurstone & T.G. ThurstoneFACTOR & THEORY-BASEDThe classroom-deployable version of Thurstone's 7-factor battery.1942Army General Classification TestInteractiveU.S. War DepartmentMILITARY TESTINGThe WWII successor to the Army Alpha, given to about 12 million US service members.1943Minnesota Multiphasic Personality InventoryReferenceStarke R. Hathaway & J. Charnley McKinleyPERSONALITY & MOODThe foundational personality assessment instrument.1944Myers-Briggs Type Indicator (MBTI)InteractiveIsabel Briggs Myers & Katharine Cook BriggsPERSONALITY & MOODThe most popular personality test in the world by administration count.1944Raven's Mill Hill Vocabulary ScaleReferenceJohn C. RavenNON-VERBAL & PERFORMANCEThe verbal companion to the Progressive Matrices.1944Trail Making TestInteractiveUS Army Individual Test BatteryMILITARY TESTINGConnect the dots in number order (Part A), then alternating numbers and letters (Part B).
ERA 3 · 1945–1969
Standardization Era
Post-war psychometrics matured. The WAIS (1955) and WISC (1949) became gold-standard clinical batteries, Cattell defined fluid vs. crystallized intelligence, and the DAT and military batteries extended testing into vocational settings.
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1945Wechsler Memory ScaleReferenceDavid WechslerWECHSLER LINEThe first standardized clinical memory test, scored as a Memory Quotient on the WAIS metric.1947Army Classification Battery (ACB)InteractiveU.S. ArmyMILITARY TESTINGThe post-WWII multi-aptitude successor to the AGCT.1947Differential Aptitude Tests (DAT)ReferenceGeorge K. Bennett, Harold G. Seashore & Alexander G. WesmanFACTOR & THEORY-BASEDA multi-aptitude battery for vocational guidance in high schools and adult counselling.1947Halstead-Reitan Neuropsychological BatteryReferenceWard C. Halstead & Ralph M. ReitanCLINICAL & NEUROPSYCHThe foundational neuropsychological assessment battery.1947Raven's Coloured Progressive MatricesReferenceJohn C. RavenNON-VERBAL & PERFORMANCEA simpler colour variant for children aged 5–11 and older adults: 36 items in three sets.1948Law School Admission Test (LSAT)ReferenceEducational Testing Service / Law School Admission CouncilADMISSIONS & ACHIEVEMENTDeveloped by nine leading US law schools as an objective measure of aptitude for legal study.1948Wisconsin Card Sorting TestInteractiveDavid Grant & Esta BergCLINICAL & NEUROPSYCHSort cards by a hidden rule that shifts every 10 correct sorts.1949Cattell 16PF Personality FactorsReferenceRaymond B. CattellPERSONALITY & MOODA 16-factor model of personality built with factor analysis.1949Cattell Culture Fair Intelligence TestReferenceRaymond B. CattellNON-VERBAL & PERFORMANCEItems designed to be as independent as possible of language, schooling and cultural knowledge.1949Graduate Record Examinations (GRE)ReferenceCarnegie Foundation / ETSADMISSIONS & ACHIEVEMENTThe standardized test for US graduate school admissions.1949Wechsler Intelligence Scale for Children (WISC)ReferenceDavid WechslerWECHSLER LINEBrought the Verbal IQ + Performance IQ structure to children aged 5–15.1954Lorge-Thorndike Intelligence TestsReferenceIrving Lorge & Robert L. ThorndikeGROUP SCHOOL TESTSThe dominant US group IQ test for school-age children from 1954 through the 1970s.1955Wechsler Adult Intelligence Scale (WAIS)ReferenceDavid WechslerWECHSLER LINEThe first adult Wechsler with its own adult norms; carried forward the deviation IQ (mean 100, SD 15) from the 1939 Wechsler-Bellevue.1959Peabody Picture Vocabulary TestReferenceLloyd DunnCLINICAL & NEUROPSYCHHear a word, point to the matching picture — a 15-minute test with no reading required.1960Hamilton Depression Rating Scale (HAM-D)ReferenceMax HamiltonPERSONALITY & MOODThe first widely used clinician-administered depression rating scale.1961Beck Depression Inventory (BDI)ReferenceAaron T. BeckPERSONALITY & MOODThe most-used depression assessment instrument in the world.1962d2 Test of AttentionReferenceRolf BrickenkampCLINICAL & NEUROPSYCHScan 14 lines of "p" and "d" letters, crossing out only the "d"s with exactly two marks.1963Goodenough-Harris Drawing TestReferenceFlorence Goodenough & Dale HarrisNON-VERBAL & PERFORMANCEThe 1963 revision of Draw-A-Man that added a Draw-A-Woman component.1963Slosson Intelligence TestReferenceRichard SlossonBINET LINEA 15-minute oral screening IQ test for ages 4 to adult, correlating r = 0.9 with the Stanford-Binet.1967Otis-Lennon School Ability TestReferenceArthur S. Otis & Roger T. LennonGROUP SCHOOL TESTSThe modern direct descendant of Otis's 1918 and 1936 group tests.1967Wechsler Preschool and Primary Scale of Intelligence (WPPSI)ReferenceDavid WechslerWECHSLER LINEThe preschool adaptation that completed Wechsler's three-instrument family.1968Armed Services Vocational Aptitude Battery (ASVAB)ReferenceU.S. Department of DefenseMILITARY TESTINGThe cognitive battery administered to every US military recruit.1968Cognitive Abilities Test (CogAT)ReferenceRobert L. Thorndike & Elizabeth HagenGROUP SCHOOL TESTSA comprehensive multi-factor school cognitive battery for grades K–12.
ERA 4 · 1970–1999
Modernization Era
CHC theory unified the field. The WISC-R (1974) and WAIS-R (1981) refined deviation IQ, the Big Five (1981) reshaped personality testing, and computer-adaptive testing began.
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1970State-Trait Anxiety Inventory (STAI)ReferenceCharles D. SpielbergerPERSONALITY & MOODThe most-used anxiety assessment instrument in the world.1974WISC-R (Wechsler Intelligence Scale for Children - Revised)ReferenceDavid WechslerWECHSLER LINEThe dominant child IQ test from 1974 through 1991: 12 subtests for ages 6–16.1975Mini-Mental State ExaminationInteractiveMarshal Folstein, Susan Folstein, Paul McHughCLINICAL & NEUROPSYCHAn 11-item bedside screen scored 0–30, the world's most-used dementia screening tool.1977Woodcock-Johnson Tests of Cognitive AbilitiesReferenceRichard W. Woodcock & Mary E. Bonner JohnsonFACTOR & THEORY-BASEDA broad cognitive and achievement battery; its later revisions were built on Gf-Gc (1989) and then CHC theory (2001).1981Big Five Personality ModelInteractiveLewis Goldberg & numerous contributorsPERSONALITY & MOODThe dominant modern personality model, derived by factor analysis of trait language.1981WAIS-R (Wechsler Adult Intelligence Scale - Revised)ReferenceDavid Wechsler / Psychological CorporationWECHSLER LINEUpdated norms and scoring; the dominant US adult intelligence test until 1997.1983Boston Naming TestReferenceEdith Kaplan, Harold Goodglass, Sandra WeintraubCLINICAL & NEUROPSYCHName 60 line drawings of increasing difficulty — the standard clinical word-finding test.1983Kaufman Assessment Battery for Children (K-ABC)ReferenceAlan S. Kaufman & Nadeen L. KaufmanFACTOR & THEORY-BASEDThe first major child battery based on Luria's neuropsychological theory.1985NEO Personality Inventory (NEO-PI)ReferencePaul T. Costa Jr. & Robert R. McCraePERSONALITY & MOODThe first major commercial personality assessment based on the Big Five.1987CVLT (California Verbal Learning Test)ReferenceDean Delis, Joel Kramer, Edith Kaplan, Beth OberCLINICAL & NEUROPSYCHLearn a 16-word "Monday shopping list" over five trials, then recall it after delays.1990Differential Ability Scales (DAS)ReferenceColin ElliottFACTOR & THEORY-BASED17 cognitive subtests for ages 2.5 to 17, with strong fluid/crystallized differentiation.1996Naglieri Nonverbal Ability Test (NNAT)ReferenceJack NaglieriNON-VERBAL & PERFORMANCEA language-free matrix test widely used for gifted-and-talented identification.1997Das-Naglieri Cognitive Assessment System (CAS)ReferenceJ.P. Das & Jack A. NaglieriFACTOR & THEORY-BASEDBuilt on the PASS theory: Planning, Attention, Simultaneous and Successive processing.1997WAIS-III (Wechsler Adult Intelligence Scale - Third Edition)ReferenceDavid Wechsler / Psychological CorporationWECHSLER LINEIntroduced four Index scores alongside the traditional Verbal and Performance IQ.
ERA 5 · 2000–2026
Contemporary Era
Modern batteries — Stanford-Binet 5 (2003), WAIS-IV (2008), WMS-IV (2009), WAIS-5 (2024) — and free online testing built on Item Response Theory, with digital adaptive scoring, 21st-century norms and CHC-rooted subtests.
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2003Reynolds Intellectual Assessment Scales (RIAS)ReferenceCecil Reynolds & Randy KamphausFACTOR & THEORY-BASEDA brief 35-minute individual IQ test for ages 3–94.2003Stanford-Binet 5 (SB5)ReferenceGale RoidBINET LINEFive factors measured in both verbal and non-verbal domains.2003WISC-IV (Wechsler Intelligence Scale for Children - Fourth Edition)ReferenceNCS PearsonWECHSLER LINEIntroduced four composite scores alongside Full Scale IQ.2008WAIS-IV (Wechsler Adult Intelligence Scale - Fourth Edition)ReferenceNCS PearsonWECHSLER LINE10 core and 5 supplemental subtests organized into four indices.2009WMS-IV (Wechsler Memory Scale - Fourth Edition)ReferenceNCS PearsonWECHSLER LINESeven subtests yielding five index scores for ages 16–90.2012WPPSI-IV (Wechsler Preschool and Primary Scale of Intelligence - Fourth Edition)ReferenceNCS PearsonWECHSLER LINEThe current Wechsler test for young children aged 2:6 to 7:7.2014WISC-V (Wechsler Intelligence Scale for Children - Fifth Edition)ReferenceNCS PearsonWECHSLER LINEFive primary indices for ages 6–16.2024WAIS-5 (Wechsler Adult Intelligence Scale - Fifth Edition)ReferenceNCS PearsonWECHSLER LINEThe newest Wechsler adult test, with revised norms and 7 Cognitive Domain scores plus FSIQ.2025What's Your IQ TestTake it nowWhat's Your IQFACTOR & THEORY-BASEDA free 30-minute online IQ test scored with Item Response Theory (3PL) on the 100-mean, 15-SD scale, with a four-domain breakdown and calibration on 5,000+ completed tests.
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The IQ Tests Timeline is part of the Historical IQ Tests Archive. Editorial content and curation are released under Creative Commons Attribution-ShareAlike 4.0 International (CC BY-SA 4.0).
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