ConductCognition

  • Domains

    Tests

    • Processing speed43
    • Attention113
    • Working memory50
    • Executive function143
    • Episodic memory72
    • Response inhibition9
    • Social cognition75
    • Language42

    Most used

    Evidence

    1. Verbal Fluency TestGradeA
    2. Stroop Color-Word TestGradeA
    3. Trail Making TestGradeA
    4. N-Back TaskGradeA
    5. Go/No-Go TaskGradeA
    6. Digit Span TestGradeA
    7. Symbol Coding TestGradeA
    8. Verbal Learning TestGradeA
    REDTry it nowStroop Color-Word Test
    All 547 tests

    Browse by

    • Phone290
    • Tablet323
    • Untimed326
    • Up to 5 minutes69
    • Evidence grade A40

  • First studies

    Grade, length

    • Reaction Time StudyGradeA7 min
    • Pilot ScreeningGradeA15 min
    • Medication StudiesGradeA−26 min
    • Language-Minimized ScreeningGradeA−30 min

    Age groups

    • Older Adult Executive SpeedGradeA20 min
    • School-AgeGradeA−33 min

    Memory

    • At-Home MemoryGradeA26 min
    • Working Memory and LearningGradeA−19 min
    • Associative MemoryGradeB32 min
    • Working Memory CapacityGradeB34 min

    Language and perception

    • LanguageGradeA−33 min
    • Visual PerceptionGradeB27 min
    • Listening and Auditory ProcessingGradeB31 min

    Executive function and attention

    • Executive ControlGradeA18 min
    • Attention and ImpulsivityGradeA−26 min
    • Visual AttentionGradeB27 min
    • Creativity and Flexible ThinkingGradeB30 min
    • Reasoning and SpatialGradeB32 min

    Movement

    • Motor and AttentionGradeA−29 min
    • Motor LearningGradeB34 min

    Behavior, mood and choice

    • Food Choice and Self-ControlGradeA−29 min
    • Sleep and FatigueGradeB23 min
    • Social CognitionGradeB23 min
    • Impulsivity and Substance UseGradeB26 min
    • Emotion and MoodGradeB28 min
    • Decisions and RewardGradeB29 min
    All 26 batteries

    Find one

    Up to 15 minutes2Up to 30 minutes19Phone8
    Test order labBattery gradesHow batteries work

  • Use and evidence

    • Overview
    • Compare all 547 tests
    • Test-retest
    • Reliability and validity
    • Battery grades26
    • Download and cite

    Clinical trials

    • Overview
    • By condition25
    • By test101
    • Trial design benchmark
    • Cognitive outcomes, 2026

    Conditions

    Registered studies

    • Dementia and Alzheimer's1,673
    • Aging, frailty and exercise1,398
    • Depression and bipolar disorder1,247
    • Stroke1,233
    • Substance use and addiction895
    • Parkinson's disease892
    • Cancer760
    All 25 conditions
    16,361Registered studies name a cognitive test in an outcome measure11,688 name a test you can run hereExplore the studies
  • 1

    Build

    • Study design
    • Customize tests
    • Repeat visits
    • Study cost calculator
    2

    Recruit

    • Recruitment setup
    • Prolific
    • Sona Systems
    • CloudResearch Connect
    • Qualtrics
    3

    Run

    • Remote testing
    • Participant devices
    • Phone timing check
    • Offline edition
    4

    Results

    • Automated scoring
    • Test norms
    • Study Quality Monitor
    • Data export
    Platform overview

    Compliance

    • HIPAA-ready testing
    • US clinical research
    • Data Policy
    • Privacy Policy
    • Terms of Use

  • Research areas

    Tests used in each

    • Aging and dementia188
    • Decisions and reward105
    • Child development and education87
    • Language and bilingualism64
    • Social behavior62
    • Psychiatric groups35
    • Training and intervention28
    • Mood, anxiety and trauma25
    • Substance use and impulsivity25
    • Neurological and movement research19
    • Brain injury and concussion14
    • Sleep and fatigue14
    • ADHD11
    • Eating and obesity8
    • Medication and drug trials8

    Research settings

    • Student participant pools
    • Teaching a class
    • Clinical trials
    • US clinical research
    • Sites without internet
    Planning a study?

  • Methods

    • How evidence grades work
    • How test batteries work
    • How test order works
    Methods and questions

    Help

    • FAQ
    • Recruitment guides
    • Compare platforms

    Updates

    • Blog
    • New tests by email
    Latest post10 November 2026What you can do in ConductCognition todayA short tour of ConductCognition as it stands on 10 November. After this, we'll post when something changes how you run a study.Read the post
  • Pricing
Start Free
Log In
Log InStart Free
  1. Home
  2. /Data
  3. /Clinical trials

Data

Cognitive tests in clinical trials: 16,361 registered studies

Every study on ClinicalTrials.gov that names a cognitive test in an outcome measure: which tests trials use, for which conditions, how large the trials are and how that is changing, with a page for each condition and each test.

Registered studies name a cognitive test in an outcome measure
16,361
Name a test you can run here
11,688
Explore them
Name one in a primary outcome
6,794
See the tests
Benchmark a trial designCognitive outcomes in trials, 2026

The tests trials use most

The Trail Making Test is the cognitive test registered studies name most: 2,293 of 16,361, 14%. Next comes the Stroop Color-Word Test (1,929). As a primary outcome, the Stroop Color-Word Test leads, with 785 studies.

  1. 1

    Trail Making Test2,293 studies, 709 as a primary outcome

  2. 2

    Stroop Color-Word Test1,929 studies, 785 as a primary outcome

  3. 3

    Verbal Learning1,832 studies, 711 as a primary outcome

  4. 4

    Verbal Fluency1,745 studies, 640 as a primary outcome

  5. 5

    Digit Span Test1,629 studies, 603 as a primary outcome

  6. 6

    Symbol Coding1,457 studies, 451 as a primary outcome

  7. 7

    N-Back Task790 studies, 381 as a primary outcome

  8. 8

    Go/No-Go Task702 studies, 309 as a primary outcome

  9. 9

    Continuous Performance Test638 studies, 265 as a primary outcome

  10. 10

    Category Fluency623 studies, 232 as a primary outcome

  11. 11

    Picture Naming Test466 studies, 201 as a primary outcome

  12. 12

    Card Sorting Test (Berg)411 studies, 139 as a primary outcome

  13. 13

    Psychomotor Vigilance Task395 studies, 154 as a primary outcome

  14. 14

    Paced Visual Serial Addition Test337 studies, 140 as a primary outcome

  15. 15

    Eriksen Flanker Task334 studies, 177 as a primary outcome

  16. 16

    Task Switching Test334 studies, 132 as a primary outcome

  17. 17

    Stop-Signal Task321 studies, 147 as a primary outcome

  18. 18

    Short Story Recall315 studies, 129 as a primary outcome

  19. 19

    Clock Drawing Task281 studies, 98 as a primary outcome

  20. 20

    Complex Figure Copy and Recall276 studies, 107 as a primary outcome

A test as a primary outcomeOnly in secondary or other outcomes

All 101 tests with their own page

Studies by start year

Each study counted once, however many tests it names. 2026 is partly planned starts.
05001,0001,5002000: 12 studies, 5 with a test as a primary outcome20002001: 13 studies, 5 with a test as a primary outcome2002: 36 studies, 20 with a test as a primary outcome2003: 52 studies, 22 with a test as a primary outcome2004: 63 studies, 29 with a test as a primary outcome2005: 69 studies, 35 with a test as a primary outcome20052006: 91 studies, 36 with a test as a primary outcome2007: 132 studies, 53 with a test as a primary outcome2008: 159 studies, 68 with a test as a primary outcome2009: 199 studies, 91 with a test as a primary outcome2010: 235 studies, 101 with a test as a primary outcome20102011: 287 studies, 119 with a test as a primary outcome2012: 324 studies, 148 with a test as a primary outcome2013: 436 studies, 192 with a test as a primary outcome2014: 542 studies, 211 with a test as a primary outcome2015: 601 studies, 257 with a test as a primary outcome20152016: 720 studies, 295 with a test as a primary outcome2017: 851 studies, 320 with a test as a primary outcome2018: 893 studies, 369 with a test as a primary outcome2019: 1,076 studies, 482 with a test as a primary outcome2020: 938 studies, 398 with a test as a primary outcome20202021: 1,269 studies, 561 with a test as a primary outcome2022: 1,276 studies, 512 with a test as a primary outcome2023: 1,410 studies, 581 with a test as a primary outcome2024: 1,524 studies, 661 with a test as a primary outcome2025: 1,591 studies, 620 with a test as a primary outcome20252026: 1,442 studies, 562 with a test as a primary outcome

A test as a primary outcomeOnly in secondary or other outcomes

Show as a table
Registered studies by start year
Start yearStudiesA test as a primary outcome
2000125
2001135
20023620
20035222
20046329
20056935
20069136
200713253
200815968
200919991
2010235101
2011287119
2012324148
2013436192
2014542211
2015601257
2016720295
2017851320
2018893369
20191,076482
2020938398
20211,269561
20221,276512
20231,410581
20241,524661
20251,591620
20261,442562

Not shown: 23 studies that started before 2000 and 91 planned to start after 2026.

Explore the studies

The 11,688 studies that name a test in the library. Choose a filter, or a bar, to narrow them; each study links to its record on ClinicalTrials.gov. The other 4,673 name only instruments outside the library.

11,688 studies match. 5,264 name a library test in a primary outcome. Median size 60 participants. Median time to the primary outcome: 8 weeks.

Loading 11,688 studies; the filters turn on when they arrive.

By start year
05001,0001,5002000: 8 studies, 3 naming a library test in a primary outcome20002001: 10 studies, 4 naming a library test in a primary outcome2002: 31 studies, 18 naming a library test in a primary outcome2003: 41 studies, 20 naming a library test in a primary outcome2004: 51 studies, 24 naming a library test in a primary outcome2005: 61 studies, 30 naming a library test in a primary outcome20052006: 76 studies, 31 naming a library test in a primary outcome2007: 106 studies, 46 naming a library test in a primary outcome2008: 123 studies, 57 naming a library test in a primary outcome2009: 164 studies, 75 naming a library test in a primary outcome2010: 196 studies, 93 naming a library test in a primary outcome20102011: 239 studies, 104 naming a library test in a primary outcome2012: 253 studies, 134 naming a library test in a primary outcome2013: 346 studies, 171 naming a library test in a primary outcome2014: 412 studies, 184 naming a library test in a primary outcome2015: 463 studies, 211 naming a library test in a primary outcome20152016: 559 studies, 245 naming a library test in a primary outcome2017: 637 studies, 260 naming a library test in a primary outcome2018: 662 studies, 304 naming a library test in a primary outcome2019: 794 studies, 384 naming a library test in a primary outcome2020: 595 studies, 283 naming a library test in a primary outcome20202021: 902 studies, 444 naming a library test in a primary outcome2022: 890 studies, 386 naming a library test in a primary outcome2023: 979 studies, 430 naming a library test in a primary outcome2024: 1,009 studies, 458 naming a library test in a primary outcome2025: 1,034 studies, 425 naming a library test in a primary outcome20252026: 958 studies, 402 naming a library test in a primary outcome

2026 is partly planned starts. Not shown: 15 that started before 2000, 68 planned to start after 2026 and 6 with no start year.

Show as a table
Matching studies by start year
Start yearStudiesAs a primary outcome
200083
2001104
20023118
20034120
20045124
20056130
20067631
200710646
200812357
200916475
201019693
2011239104
2012253134
2013346171
2014412184
2015463211
2016559245
2017637260
2018662304
2019794384
2020595283
2021902444
2022890386
2023979430
20241,009458
20251,034425
2026958402

Library tests named most

Largest condition groups

Phases

Participants

Lead sponsor: industry 1,111, NIH 68, other 10,509. Interventional 10,190, observational 1,498.

As a primary outcomeSecondary or other outcome

The studies, newest registration first

Each number opens the study's record on ClinicalTrials.gov.

Registered studies that match the filters, newest registration first, with the library tests each one names and the outcome list that names them.
StudyStartPhaseConditionsParticipantsLead sponsorStatusLibrary tests named, with the latest time point
NCT07908147Start2027PhaseEarly phase 1ConditionsCancerParticipants12Lead sponsorOtherStatusNot yet recruitingLibrary tests named
  • Trail Making TestSecondary5 years
  • Verbal LearningSecondary5 years
  • Verbal FluencySecondary5 years
  • Digit Span TestSecondary5 years
NCT07907718Start2026PhaseNot applicableConditionsParkinson's diseaseParticipants50Lead sponsorOtherStatusNot yet recruitingLibrary tests named
  • Trail Making TestPrimary8 weeks
  • Stroop Color-Word TestPrimary8 weeks
  • Go/No-Go TaskPrimary8 weeks
NCT07906847Start2026PhaseObservationalConditionsPain and fatigueParticipants80Lead sponsorOtherStatusNot yet recruitingLibrary tests named
  • Trail Making TestPrimary
  • Stroop Color-Word TestPrimary
  • Digit Span TestPrimary
NCT07905430Start2026PhaseNot applicableConditionsOther conditionsParticipants152Lead sponsorOtherStatusRecruitingLibrary tests named
  • Go/No-Go TaskSecondarysame day
NCT07904325Start2026PhaseObservationalConditionsCardiovascular disease, Lung diseaseParticipants100Lead sponsorOtherStatusNot yet recruitingLibrary tests named
  • Card Sorting Test (Berg)Secondarysame day
  • Lexical Decision TaskSecondarysame day
NCT07903896Start2026PhaseNot applicableConditionsDepression and bipolar disorder, Sleep and sleep disorders, Anxiety, PTSD and OCDParticipants75Lead sponsorOtherStatusRecruitingLibrary tests named
  • N-Back TaskSecondary
  • Eriksen Flanker TaskSecondary
NCT07902206Start2026PhaseNot applicableConditionsAging, frailty and exercise, Huntington's diseaseParticipants88Lead sponsorOtherStatusNot yet recruitingLibrary tests named
  • Trail Making TestSecondary6 months
  • Stroop Color-Word TestSecondary6 months
  • Verbal FluencySecondary6 months
  • Symbol CodingSecondary6 months
NCT07902076Start2027PhaseObservationalConditionsAnxiety, PTSD and OCDParticipants280Lead sponsorOtherStatusNot yet recruitingLibrary tests named
  • Eriksen Flanker TaskPrimarysame day
NCT07900893Start2026PhaseNot applicableConditionsSchizophrenia and psychosis, Healthy volunteersParticipants10,000Lead sponsorOtherStatusRecruitingLibrary tests named
  • Probabilistic Reversal LearningPrimarysame day
  • Trust GamePrimarysame day
  • Cue Blocking TaskPrimarysame day
NCT07900451Start2026PhaseObservationalConditionsADHDParticipants90Lead sponsorOtherStatusRecruitingLibrary tests named
  • Continuous Performance TestSecondarysame day
  • AX Continuous Performance TestWording unclear
NCT07900048Start2026PhaseNot applicableConditionsADHDParticipants100Lead sponsorOtherStatusNot yet recruitingLibrary tests named
  • Continuous Performance TestPrimary16 weeks
  • Tower PlanningPrimary16 weeks
  • AX Continuous Performance TestWording unclear
NCT07899827Start2027PhaseNot applicableConditionsCancer, Substance use and addictionParticipants50Lead sponsorOtherStatusNot yet recruitingLibrary tests named
  • Purchase TaskPrimary4 weeks
NCT07899671Start2026PhaseNot applicableConditionsOther conditionsParticipants160Lead sponsorOtherStatusNot yet recruitingLibrary tests named
  • Serial Naming TaskOther outcome
NCT07899528Start2026PhaseNot applicableConditionsOther conditionsParticipants112Lead sponsorOtherStatusRecruitingLibrary tests named
  • Verbal FluencySecondary2 weeks
NCT07899242Start2025PhaseNot applicableConditionsOther conditionsParticipants242Lead sponsorOtherStatusCompletedLibrary tests named
  • Trail Making TestSecondary5 months
  • Stroop Color-Word TestSecondary5 months
  • Digit Span TestSecondary5 months
NCT07898722Start2025PhaseNot applicableConditionsAnxiety, PTSD and OCD, Pain and fatigueParticipants40Lead sponsorOtherStatusCompletedLibrary tests named
  • Symbol CodingSecondary
NCT07898371Start2026PhaseObservationalConditionsMultiple sclerosisParticipants3,000Lead sponsorIndustryStatusRecruitingLibrary tests named
  • Symbol CodingSecondary3 years
NCT07897474Start2026PhaseObservationalConditionsSleep and sleep disordersParticipants100Lead sponsorOtherStatusNot yet recruitingLibrary tests named
  • Trail Making TestPrimary
  • Stroop Color-Word TestPrimary
  • Digit Span TestPrimary
  • Symbol CodingPrimary
  • Psychomotor Vigilance TaskPrimary
NCT07897214Start2026PhaseNot applicableConditionsOther conditionsParticipants15Lead sponsorOtherStatusRecruitingLibrary tests named
  • N-Back TaskSecondarysame day
NCT07897175Start2026PhaseNot applicableConditionsHealthy volunteersParticipants54Lead sponsorOtherStatusNot yet recruitingLibrary tests named
  • Stroop Color-Word TestPrimary1 week
  • Choice Reaction TimePrimary1 week
  • Simple Reaction TimePrimary1 week
  • Arithmetic Fluency TaskPrimary1 week
NCT07897084Start2026PhaseNot applicableConditionsOther conditionsParticipants120Lead sponsorOtherStatusNot yet recruitingLibrary tests named
  • Arithmetic Fluency TaskSecondary3 weeks
NCT07895979Start2026PhaseNot applicableConditionsCognitive impairment and declineParticipants216Lead sponsorOtherStatusRecruitingLibrary tests named
  • Tower of HanoiSecondary12 weeks
NCT07895797Start2026PhaseNot applicableConditionsBrain injury and concussionParticipants38Lead sponsorOtherStatusNot yet recruitingLibrary tests named
  • Simple Reaction TimeSecondary
NCT07895407Start2025PhasePhase 4ConditionsDelirium, surgery and intensive careParticipants148Lead sponsorOtherStatusRecruitingLibrary tests named
  • Clock Drawing TaskSecondarysame day
NCT07894965Start2026PhaseNot applicableConditionsPain and fatigueParticipants90Lead sponsorOtherStatusNot yet recruitingLibrary tests named
  • Arithmetic Fluency TaskSecondary12 weeks

Page 1 of 468

Tests by condition

How many studies of each condition name each test. Switch to the share of the condition's studies, or to how often the test is a primary outcome there. An underlined cell, 50 studies or more, opens its own page.

Cells show

Registered studies in the condition group that name the test in an outcome measure.

  • None
  • 1 to 9
  • 10 to 24
  • 25 to 49
  • 50 to 99
  • 100 or more
Registered studies that name each library test, by condition group. The cells show: studies.
TestDementiaDementia and Alzheimer's1,673 studies in allAgingAging, frailty and exercise1,398 studies in allDepressionDepression and bipolar disorder1,247 studies in allStrokeStroke1,233 studies in allSubstance useSubstance use and addiction895 studies in allParkinson'sParkinson's disease892 studies in allMCIMild cognitive impairment859 studies in allCancerCancer760 studies in allSleepSleep and sleep disorders749 studies in allAnxietyAnxiety, PTSD and OCD692 studies in allHeartCardiovascular disease682 studies in allPainPain and fatigue681 studies in allHealthyHealthy volunteers656 studies in allPsychosisSchizophrenia and psychosis640 studies in allObesityObesity and diabetes627 studies in allDeliriumDelirium, surgery and intensive care619 studies in allMSMultiple sclerosis612 studies in allBrain injuryBrain injury and concussion444 studies in allADHDADHD357 studies in allImpairmentCognitive impairment and decline354 studies in allHearingHearing loss247 studies in allCOVID-19COVID-19 and long COVID221 studies in allAutismAutism200 studies in allEpilepsyEpilepsy138 studies in allLungLung disease110 studies in all
Trail Making Test2,293 studies2732552041565215621318785691059468102102694311524771736171518
Stroop Color-Word Test1,929 studies116230138105751261266589798111498461033756596147830191218
Verbal Learning1,832 studies224128178637761183235667064725611274511391118795225259
Verbal Fluency1,745 studies248136154110291401772005861615339107634658861263324141713
Digit Span Test1,629 studies181129143100488616910763725961646664442598586014318157
Symbol Coding1,457 studies1171161436160418458893146825643592937543940721174
N-Back Task790 studies4468792268134219513120315166335626301634533
Go/No-Go Task702 studies20417912801816104463122242154441012657221750
Continuous Performance Test638 studies14227316537173537375271878154639123140917101
Category Fluency623 studies167484133644922615123016114627131022422414331
Picture Naming Test466 studies10423199923771148614257141021502336380
Card Sorting Test (Berg)411 studies1223651327231510212910111850112317158111751
Psychomotor Vigilance Task395 studies7131842010752371210353111652422030510
Paced Visual Serial Addition Test337 studies591763064152013328101373169182301123
Eriksen Flanker Task334 studies12453351510371822612303251410186211211
Task Switching Test334 studies3137201671422162112131316141333185774701
Stop-Signal Task321 studies571919210241429691052400449101912
Short Story Recall315 studies9132271231174144113371916921011044030
Clock Drawing Task281 studies693511194334111542064211202002113012
Complex Figure Copy and Recall276 studies531017153213184896512127415114281101
Matrix Reasoning272 studies25202111114134111059162119131098431440
Choice Reaction Time270 studies252336491556178413205132347503161
Delay Discounting257 studies15191104418161276109361008000000
Cancellation Test253 studies42915752355573586601175312110
Tower Planning247 studies91829791354919311940635920306720
Dimensional Change Card Sort214 studies13371210719610121221201822969121351
Simple Reaction Time210 studies1314195714421513222201415151307040
Paired Associate Learning204 studies34141261551161892143011121251704223
Rapid Visual Information Processing204 studies8122551413711135181813120247604100
Vocabulary Test199 studies59774139449274801816902190

Compare tests over time

Studies per start year for up to four tests. Each panel draws one test in blue and the others for scale.
Trail Making Test2,281 studies, 2000 to 2026
01252502000201020202026
Stroop Color-Word Test1,922 studies, 2000 to 2026
01252502000201020202026
Verbal Learning1,819 studies, 2000 to 2026
01252502000201020202026
Verbal Fluency1,737 studies, 2000 to 2026
01252502000201020202026

The panel's testThe other tests chosenEvery panel has the same scale. 2026 is partly planned starts.

Show as a table
Registered studies per start year that name each test
Start yearTrail Making TestStroop Color-Word TestVerbal LearningVerbal Fluency
20002311
20010351
20023583
200382144
2004108149
200514111719
2006146139
200721132222
200817152818
200929162829
201032294229
201147313336
201244324234
201360425358
201466648259
201585679179
2016103859885
20171227910793
201811710392107
2019155119122121
2020122997690
2021172151137131
2022188168138123
2023228198157147
2024211182144130
2025210198132167
2026201193123133

Rising and falling tests

How much each test's share of new registered studies changed, from studies that started in 2016 to 2020 (4,478) to those that started in 2021 to 2025 (7,070). Of the 49 tests with at least 30 studies in the earlier years, these grew and shrank most; the tables give each share.
+75%+50%+25%Same−25%−50%−75%2016 to 20202021 to 2025Attention Network Test +50%Dimensional Change Card Sort +35%Eriksen Flanker Task +28%Corsi Block-Tapping Test +19%Stroop Color-Word Test +17%Stop-Signal Task −36%Arithmetic Fluency Task −44%Paced Visual Serial Addition Test −48%Dot-Probe Task −54%Letter-Number Sequencing Task −55%

Rising

Rising tests: share of new studies, 2016 to 2020 and 2021 to 2025
Test2016 to 20202021 to 2025Change
Attention Network Test0.7%1.1%Up 50%
Dimensional Change Card Sort1.3%1.8%Up 35%
Eriksen Flanker Task1.8%2.3%Up 28%
Corsi Block-Tapping Test1.1%1.3%Up 19%
Stroop Color-Word Test10.8%12.7%Up 17%

Falling

Falling tests: share of new studies, 2016 to 2020 and 2021 to 2025
Test2016 to 20202021 to 2025Change
Letter-Number Sequencing Task1.4%0.6%Down 55%
Dot-Probe Task1.5%0.7%Down 54%
Paced Visual Serial Addition Test2.4%1.3%Down 48%
Arithmetic Fluency Task0.8%0.5%Down 44%
Stop-Signal Task2.7%1.8%Down 36%

How many participants trials enroll

Enrollment as registered: the actual count for a finished study, the planned count for one still recruiting. Half of the studies in a phase enroll fewer than its median.
1020501002005001,000
  • Early phase 136 median, 20 to 71
  • Phase 130 median, 17 to 57
  • Phase 1/236 median, 18 to 60
  • Phase 260 median, 32 to 120
  • Phase 2/3100 median, 48 to 240
  • Phase 3246 median, 83 to 669
  • Phase 477 median, 36 to 159
  • Not applicable60 median, 31 to 114
  • Observational111 median, 57 to 300
Participants per study. The bar spans the middle half of the studies in each phase, the mark is the median, and the axis is logarithmic. Phases with fewer than 10 studies that give a size are left out.
Show as a table
Participants per study by phase
PhaseStudies with a sizeMedianMiddle half
Early phase 12173620 to 71
Phase 15043017 to 57
Phase 1/22853618 to 60
Phase 21,3416032 to 120
Phase 2/315510048 to 240
Phase 363524683 to 669
Phase 46717736 to 159
Not applicable9,6826031 to 114
Observational2,55911157 to 300

When trials measure the cognitive outcome

Half of the primary outcomes that name a library test are measured within 8 weeks of the start, and the middle half from 1 week to 6 months. 9,314 primary outcomes give a duration.

Latest time point of each outcome

  • Within a day3,923 outcomes, 1,915 as a primary outcome
  • Up to 4 weeks4,276 outcomes, 1,730 as a primary outcome
  • 1 to 3 months6,757 outcomes, 2,641 as a primary outcome
  • 3 to 6 months3,981 outcomes, 1,350 as a primary outcome
  • 6 to 12 months2,682 outcomes, 858 as a primary outcome
  • 1 to 2 years1,241 outcomes, 428 as a primary outcome
  • Over 2 years1,054 outcomes, 392 as a primary outcome
  • No duration given1,679 outcomes, 799 as a primary outcome

A test as a primary outcomeOnly in secondary or other outcomes

23,914 of the 25,593 outcome measures give a duration. A single visit counts as within a day.

Median time to the primary outcome, by test

Median weeks to the latest time point of each test's primary outcomes
TestPrimary outcomesMedian
Stroop Color-Word Test7248 weeks
Verbal Learning66513 weeks
Trail Making Test65912 weeks
Verbal Fluency59913 weeks
Digit Span Test57012 weeks
Symbol Coding42012 weeks
N-Back Task3504 weeks
Go/No-Go Task2826 weeks
Continuous Performance Test2488 weeks
Category Fluency21815 weeks

What industry trials use

1,631 of the studies are led by a company, 76 by the NIH and 14,654 by universities, hospitals and others. 13,771 are interventional and 2,590 observational. The tests industry-led studies name most often in a primary outcome:
  1. 1

    Symbol Coding273 studies, 60 as a primary outcome

  2. 2

    Verbal Learning148 studies, 41 as a primary outcome

  3. 3

    Verbal Fluency139 studies, 39 as a primary outcome

  4. 4

    Trail Making Test141 studies, 33 as a primary outcome

  5. 5

    Choice Reaction Time78 studies, 33 as a primary outcome

  6. 6

    Digit Span Test102 studies, 31 as a primary outcome

  7. 7

    Stroop Color-Word Test95 studies, 26 as a primary outcome

  8. 8

    Continuous Performance Test54 studies, 21 as a primary outcome

  9. 9

    Category Fluency76 studies, 20 as a primary outcome

  10. 10

    Simple Reaction Time53 studies, 20 as a primary outcome

A test as a primary outcomeOnly in secondary or other outcomes

Status, results, interventions and countries

3,024 of the studies are recruiting now. Every registered study counts here, whichever tests it names; the dark part of each bar is the studies with a cognitive test as a primary outcome.

Status

  • Recruiting3,024 studies, 1,136 as a primary outcome
  • Not yet recruiting1,048 studies, 408 as a primary outcome
  • Active, not recruiting688 studies, 264 as a primary outcome
  • Completed7,953 studies, 3,546 as a primary outcome
  • Stopped early1,099 studies, 408 as a primary outcome
  • Status unknown2,549 studies, 1,032 as a primary outcome

What they test

  • Behavioral4,208 studies, 1,910 as a primary outcome
  • Drug3,904 studies, 1,308 as a primary outcome
  • Device2,887 studies, 1,162 as a primary outcome
  • Dietary supplement889 studies, 428 as a primary outcome
  • Procedure670 studies, 225 as a primary outcome
  • Diagnostic test381 studies, 159 as a primary outcome
  • Biological238 studies, 52 as a primary outcome
  • Radiation191 studies, 60 as a primary outcome
  • Combination product73 studies, 29 as a primary outcome
  • Genetic43 studies, 17 as a primary outcome
  • Other4,228 studies, 1,825 as a primary outcome
  • None given1,117 studies, 539 as a primary outcome

Intervention types as registered. A study can list several; observational studies often list none.

Where their sites are

  • United States5,548 studies, 2,549 as a primary outcome
  • China1,348 studies, 450 as a primary outcome
  • France1,058 studies, 299 as a primary outcome
  • Canada1,028 studies, 312 as a primary outcome
  • United Kingdom870 studies, 263 as a primary outcome
  • Spain803 studies, 271 as a primary outcome
  • Germany750 studies, 205 as a primary outcome
  • Italy723 studies, 267 as a primary outcome
  • Türkiye702 studies, 372 as a primary outcome
  • Taiwan513 studies, 236 as a primary outcome
  • Netherlands417 studies, 101 as a primary outcome
  • Switzerland410 studies, 108 as a primary outcome

131 countries in all. A study with sites in several counts in each; 1,053 list no site.

Reported results

Completed studies with results posted on ClinicalTrials.gov, a results paper the registry links to the study, or both.

Completed studies: 3,626 of 7,953, 46%

Completed studies by how they reported results
ResultsCompleted studies
Results on ClinicalTrials.gov and a paper776, 10%
Results on ClinicalTrials.gov only1,139, 14%
A results paper only1,711, 22%
Neither4,327, 54%

Every condition

A page for each condition group with 100 or more registered studies.
  • Dementia and Alzheimer's1,673 registered studies, 661 with a test as a primary outcome, median size 83Most used: Trail Making Test (273), Verbal Fluency (248), Verbal Learning (224)
  • Aging, frailty and exercise1,398 registered studies, 580 with a test as a primary outcome, median size 78Most used: Trail Making Test (255), Stroop Color-Word Test (230), Verbal Fluency (136)
  • Depression and bipolar disorder1,247 registered studies, 464 with a test as a primary outcome, median size 74Most used: Trail Making Test (204), Verbal Learning (178), Verbal Fluency (154)
  • Stroke1,233 registered studies, 397 with a test as a primary outcome, median size 60Most used: Trail Making Test (156), Verbal Fluency (110), Stroop Color-Word Test (105)
  • Substance use and addiction895 registered studies, 411 with a test as a primary outcome, median size 60Most used: Cue Reactivity Task (158), Delay Discounting (104), Stop-Signal Task (92)
  • Parkinson's disease892 registered studies, 276 with a test as a primary outcome, median size 49Most used: Trail Making Test (156), Verbal Fluency (140), Stroop Color-Word Test (126)
  • Mild cognitive impairment859 registered studies, 508 with a test as a primary outcome, median size 72Most used: Trail Making Test (213), Verbal Learning (183), Verbal Fluency (177)
  • Cancer760 registered studies, 274 with a test as a primary outcome, median size 72Most used: Verbal Learning (235), Verbal Fluency (200), Trail Making Test (187)
  • Sleep and sleep disorders749 registered studies, 264 with a test as a primary outcome, median size 64Most used: Psychomotor Vigilance Task (237), Stroop Color-Word Test (89), Symbol Coding (89)
  • Anxiety, PTSD and OCD692 registered studies, 273 with a test as a primary outcome, median size 69Most used: Stroop Color-Word Test (79), Digit Span Test (72), Verbal Learning (70)
  • Cardiovascular disease682 registered studies, 185 with a test as a primary outcome, median size 119Most used: Trail Making Test (105), Stroop Color-Word Test (81), Verbal Learning (64)
  • Pain and fatigue681 registered studies, 237 with a test as a primary outcome, median size 60Most used: Stroop Color-Word Test (114), Trail Making Test (94), Symbol Coding (82)
  • Healthy volunteers656 registered studies, 354 with a test as a primary outcome, median size 60Most used: Stroop Color-Word Test (98), Trail Making Test (68), Digit Span Test (64)
  • Schizophrenia and psychosis640 registered studies, 273 with a test as a primary outcome, median size 60Most used: Verbal Learning (112), Verbal Fluency (107), Trail Making Test (102)
  • Obesity and diabetes627 registered studies, 228 with a test as a primary outcome, median size 79Most used: Stroop Color-Word Test (103), Trail Making Test (102), Verbal Learning (74)
  • Delirium, surgery and intensive care619 registered studies, 234 with a test as a primary outcome, median size 120Most used: Trail Making Test (69), Verbal Learning (51), Verbal Fluency (46)
  • Multiple sclerosis612 registered studies, 197 with a test as a primary outcome, median size 61Most used: Symbol Coding (375), Paced Visual Serial Addition Test (169), Verbal Learning (139)
  • Brain injury and concussion444 registered studies, 229 with a test as a primary outcome, median size 50Most used: Trail Making Test (115), Verbal Learning (111), Digit Span Test (98)
  • ADHD357 registered studies, 185 with a test as a primary outcome, median size 63Most used: Continuous Performance Test (123), Go/No-Go Task (65), Stroop Color-Word Test (61)
  • Cognitive impairment and decline354 registered studies, 230 with a test as a primary outcome, median size 75Most used: Verbal Learning (79), Trail Making Test (77), Verbal Fluency (63)
  • Hearing loss247 registered studies, 133 with a test as a primary outcome, median size 44Most used: Trail Making Test (17), Digit Span Test (14), Spectral Ripple Task (9)
  • COVID-19 and long COVID221 registered studies, 71 with a test as a primary outcome, median size 89Most used: Trail Making Test (36), Digit Span Test (31), Stroop Color-Word Test (30)
  • Autism200 registered studies, 84 with a test as a primary outcome, median size 60Most used: Vocabulary Test (21), Emoji Emotion Recognition (19), Stroop Color-Word Test (19)
  • Epilepsy138 registered studies, 57 with a test as a primary outcome, median size 55Most used: Verbal Learning (25), Verbal Fluency (17), Digit Span Test (15)
  • Lung disease110 registered studies, 38 with a test as a primary outcome, median size 74Most used: Trail Making Test (18), Stroop Color-Word Test (18), Verbal Fluency (13)

All conditions side by side

Every test

A page for each test that 20 or more registered studies name, with its studies.
  • Trail Making Test2,293
  • Stroop Color-Word Test1,929
  • Verbal Learning1,832
  • Verbal Fluency1,745
  • Digit Span Test1,629
  • Symbol Coding1,457
  • N-Back Task790
  • Go/No-Go Task702
  • Continuous Performance Test638
  • Category Fluency623
  • Picture Naming Test466
  • Card Sorting Test (Berg)411
  • Psychomotor Vigilance Task395
  • Paced Visual Serial Addition Test337
  • Eriksen Flanker Task334
  • Task Switching Test334
  • Stop-Signal Task321
  • Short Story Recall315
  • Clock Drawing Task281
  • Complex Figure Copy and Recall276
  • Matrix Reasoning272
  • Choice Reaction Time270
  • Delay Discounting257
  • Cancellation Test253
  • Tower Planning247
  • Dimensional Change Card Sort214
  • Simple Reaction Time210
  • Paired Associate Learning204
  • Rapid Visual Information Processing204
  • Vocabulary Test199
  • AX Continuous Performance Test191
  • Cue Reactivity Task188
  • Emoji Emotion Recognition187
  • Letter-Number Sequencing Task184
  • Selective Reminding Task183
  • Corsi Block-Tapping Test181
  • Size Order Memory Test162
  • Delayed Recall Module159
  • Dot-Probe Task148
  • Pattern and Letter Comparison147
  • Finger Tapping Task144
  • Picture Order Memory Test144
  • Attention Network Test138
  • Symbol Scan Task129
  • Iowa Gambling Lite125
  • Contrast Sensitivity Test119
  • Implicit Association Test (IAT)113
  • Monetary Incentive Delay106
  • Balloon Risk105
  • Arithmetic Fluency Task101
  • Purchase Task89
  • Oddball Target Detection86
  • Sustained Attention to Response85
  • Spatial Working Memory78
  • Delayed Match-to-Sample69
  • Line Angle Matching69
  • Antisaccade Task68
  • Line Bisection Test68
  • Emotional Stroop Task66
  • Hidden Path Learning66
  • Probabilistic Reversal Learning66
  • Mental Rotation64
  • Mnemonic Similarity Task62
  • Effort for Rewards Task61
  • Emotion Regulation Task56
  • Field of View Speed Test53
  • Face-name Memory Task51
  • One-Touch Tower Planning51
  • Intra/Extra Dimensional Set Shift50
  • Affective Go/No-Go48
  • Word Pair Learning48
  • Visual Search Test47
  • Effort Discounting Task46
  • Design Fluency Test45
  • Recognition Memory Test45
  • Pattern Recognition Memory41
  • Probabilistic Reward Task38
  • Sternberg Memory Scanning38
  • Token Commands Task36
  • Tower of Hanoi34
  • Ball-Toss Game33
  • Block Copy Test33
  • Indirect Hints Task33
  • Multi-Source Interference Task32
  • Motor Sequence Task30
  • Simon Task30
  • Approach-Avoidance Task28
  • Biological Motion Task28
  • Serial Reaction Time27
  • Trust Game26
  • Betting Choice Task24
  • Operation Span24
  • Social Slips Stories Task24
  • Mirror Tracing Task23
  • Posner Cueing23
  • Lexical Decision Task22
  • Reading Span Task22
  • Serial Naming Task22
  • Sentence Completion Inhibition Test21
  • Beads Task20
  • Scrambled Sentences Test20

Questions, answered from the data

Which cognitive test do clinical trials use most?

The Trail Making Test: 2,293 of the 16,361 registered studies name it in an outcome measure, 14%. Next come the Stroop Color-Word Test (1,929) and Verbal Learning (1,832).

Which cognitive test do trials use most as a primary outcome?

The Stroop Color-Word Test, named in a primary outcome by 785 studies. 6,794 of the 16,361 studies, 42%, name a cognitive test in a primary outcome.

Which conditions have the most trials with a cognitive outcome?

Dementia and Alzheimer's, with 1,673 registered studies, then aging, frailty and exercise (1,398) and depression and bipolar disorder (1,247). 2,897 studies fall in none of the named groups.

How many participants does a phase 2 trial with a cognitive outcome enroll?

Half of the phase 2 studies enroll 60 participants or fewer, and the middle half enroll 32 to 120. 1,341 of them give a size. Phase 3 studies enroll a median of 246.

How long after the start do trials measure a cognitive outcome?

Half of the primary outcomes that name a library test are measured within 8 weeks of the start, and the middle half from 1 week to 6 months. 9,314 primary outcomes give a duration.

Where do trials with a cognitive outcome run?

In 131 countries. The United States has sites in 5,548 of the 16,361 studies, then China (1,348) and France (1,058). 1,053 studies list no site.

How many completed trials with a cognitive outcome have reported results?

3,626 of the 7,953 completed studies, 46%, have reported results: 1,915 posted them on ClinicalTrials.gov, 2,487 have a results paper linked to the registry record, and 776 did both. The other 4,327 show neither.

Which cognitive tests are new trials using more?

Of the studies that started in 2021 to 2025, the share that name the Attention Network Test is 50% larger than in 2016 to 2020. Dimensional Change Card Sort grew 35% and The Eriksen Flanker Task grew 28%. The Letter-Number Sequencing Task fell most, by 55%.

How the studies are counted

For each test family, the census runs ClinicalTrials.gov's own outcome search for the family's names and reads every study first posted by the day the family was counted. These studies were read on 10 November 2026. A study counts once on a page, however many tests it names. Counts for a test cover every version of the task under any of its names, so a page can count studies that used a commercial version.

The census adds two things to each record and changes nothing in it: which outcome list names the test (primary, then secondary, then other), and the condition groups, matched on the study's condition names and MeSH terms. A study can fall in several groups; one whose only condition is cognitive impairment or decline falls in “Cognitive impairment and decline”. Studies that name only instruments outside the library count in every total and share but are not listed.

A second read on 10 November 2026 added each study's overall status, whether results are posted, its intervention types, the countries of its sites and the time frame of the outcome that names each test. A time frame counts by the latest time point it names: “Baseline, 12 and 24 weeks” is 24 weeks, a single visit is within a day, and one that names no duration, such as “end of treatment”, is left out of the timings.

A third read on 10 November 2026 added the papers the registry links to each study: those its sponsor lists as reporting results, and those PubMed links to it through the study's NCT number. A study has a results paper when one of them came out in or after the month of its primary completion and PubMed does not class it as a protocol, review or comment. A paper that never gives the NCT number is not linked, so some studies counted as reporting neither did publish.

Source: ClinicalTrials.gov, a database of the U.S. National Library of Medicine, which does not endorse these pages. Every study line is in the data release 2.1.0, and the explorer's own file is clinical-trials-studies.json.

More on use and evidence

  • 25 papersTest-retest evidence39 of 582 test families have 25 or more test-retest papersWhich tests have their reliability over time on record, and which well-used tests lack it.
  • 150 papersReliability and validity evidence55 of 582 test families have 150 or more reliability or validity papersPapers on each test's reliability, validity and norms, set against how much it is used.
  • Every test, every measure534 of 582 test families in the census are in the libraryThe full table, with grades, papers per year and a download.

Plan a trial's cognitive outcomes

Choose tests with a record in registered trials, and run them in a browser at every site, on the same version each visit.

Start free
ConductCognition

Hosted browser-native cognitive testing for academic and commercial research workflows.

A product of ConductScience, Inc.

New tests and features, about once a month. Unsubscribe at any time.

Tests

  • All cognitive tests
  • Test batteries
  • Use and evidence
  • Test norms
  • Trail Making Test
  • N-Back Task
  • Automated scoring
  • Study design
  • New tests by email

Guides

  • Methods and questions
  • Blog
  • Recruitment setup
  • Participant devices
  • Prolific
  • Sona Systems
  • CloudResearch Connect
  • Qualtrics

Use cases

  • Student participant pools
  • Aging and dementia research
  • Clinical trials
  • US clinical research
  • Remote testing

Compare and buy

  • Pricing
  • Compare platforms
  • Offline edition
  • FAQ

Trust

  • Study Quality Monitor
  • HIPAA-ready testing
  • Data export
  • Privacy Policy
  • Terms of Use
  • Data Policy

Company

  • ConductScience
  • Affiliate Program
© 2026 ConductScience, Inc. Research use only.