Working Memory
Brown-Peterson Task
Also called: Brown-Peterson paradigm, Peterson and Peterson task, consonant trigram recall, distractor task, short-term forgetting
Measure how fast short-term memory fades when rehearsal is blocked: three consonants, counting back by threes for 3 to 18 seconds, then recall.
8-11 minUntimed
Free to start: 10 free participants per account, then $0.99 per participant for academic research, or any yearly plan. Preview any test free after you sign up.
- Papers, 2021 to 2025
- 32
- Evidence grade
- C
- Registered clinical studies
- 3
What it measures
Measures how fast short-term memory fades when rehearsal is blocked. Participants see three consonants, count back by threes from a three-digit number for 3 to 18 seconds, then enter the letters.
Constructs
- Short-term memory
- Forgetting over seconds
- Interference
- Verbal working memory
Research uses
- Short-term memory research in aging and dementia
- Working memory studies in clinical groups
- Within-study comparison of forgetting over short delays
How the paradigm works
The Brown-Peterson task measures how fast short-term memory fades when rehearsal is blocked. On each trial three consonants appear together for 1,500 ms. A three-digit number follows, and the participant counts back from it by threes, typing each number, for 3 to 18 seconds. Then they enter the three letters in the order they saw them, by typing or on an on-screen keypad of A to Z. Counting keeps the letters from being repeated silently, so recall shows how much survives the delay.
More about the paradigm
The task follows Peterson and Peterson (1959), who tested delays of 3, 6, 9, 12, 15 and 18 seconds, eight trials at each, and found that correct recall fell from about 80% at 3 seconds to under 10% at 18 seconds. Brown (1958) had shown that consonants are forgotten within seconds when other material follows them. Here there are four trials at each delay, 24 in all (standard; two to six at each delay), each delay once in every block of six trials in an order drawn from the session's seed, after two practice trials with feedback. A fixation cross shows for 1,000 ms before each trial.
The letters are 13 consonants that the English and Italian alphabets share, less H, Q and S, which join other consonants into sounds that start words. Each trigram has three different letters, never two side by side that are neighbors in the alphabet or that start words in English, Italian, German, Spanish, French or Portuguese, and no common abbreviation. No two trigrams in a row share a letter, as in the original study. Start numbers run from 301 to 999 and never end in 0. Peterson and Peterson spoke the letters and the number and had participants count aloud with a metronome at two counts per second; here they are shown on screen, and the count is typed at the participant's own pace, each number entered at its third digit. Their syllables came from Witmer's English norms; ours are drawn by rule, so scores are best compared within studies.
The main score is the share of trigrams recalled with all three letters in order, across all delays. Recall at each delay, the drop from 3 to 18 seconds, letters recalled in their place and anywhere, and recall in the first block of six trials against the rest are also given: forgetting in this task grows over the first trials as earlier letters interfere (Keppel and Underwood 1962). The counting is scored too: the share of numbers 3 less than the number before, seconds per number, and trials with no number counted. Scores support research and do not diagnose.
Scores
- Trigrams Recalled%
- Share of trigrams entered with all three letters in the order shown, across all delays.
- Higher is better
- Recall at 3 Seconds%
- Share of trigrams recalled after 3 seconds of counting.
- Higher is better
- Recall at 6 Seconds%
- Share of trigrams recalled after 6 seconds of counting.
- Higher is better
- Recall at 9 Seconds%
- Share of trigrams recalled after 9 seconds of counting.
- Higher is better
- Recall at 12 Seconds%
- Share of trigrams recalled after 12 seconds of counting.
- Higher is better
- Recall at 15 Seconds%
- Share of trigrams recalled after 15 seconds of counting.
- Higher is better
- Recall at 18 Seconds%
- Share of trigrams recalled after 18 seconds of counting.
- Higher is better
- Drop from 3 to 18 Seconds%
- Recall at 3 seconds minus recall at 18 seconds.
- Positive values mean recall fell as the delay grew
- Letters in Place%
- Share of letters entered in the place they were shown.
- Higher is better
- Letters Anywhere%
- Share of letters shown that were entered in any place.
- Higher is better
- First Block Recall%
- Share of trigrams recalled in the first block of six trials, one at each delay.
- Informational
- Later Blocks Recall%
- Share of trigrams recalled after the first block, as earlier letters begin to interfere.
- Informational
- Counting Accuracy%
- Share of numbers counted that were 3 less than the number before: the start number, then the participant's own last number.
- Higher is better
- Seconds per Numberseconds
- Counting time divided by the numbers counted.
- Lower is faster
- Numbers Countedcount
- Numbers entered while counting, over all trials.
- Informational
- Trials Without Countingtrials
- Trials on which no number was counted, so the letters could be rehearsed.
- Lower is better
- Anticipationscount
- Trials whose first counting key came under 100 ms after the number appeared.
- Lower is better
- Median Entry Timems
- Median time from the recall screen to Submit.
- Informational
- Trials Completedtrials
- Test trials recorded in the scored run.
- Under 90% of the planned trials is invalid
- Planned Trialstrials
- Test trials the session planned to give.
- Informational
Use and evidence
32 papers from 2021 to 2025 name this task in their title or abstract, down 6% compared with 2016 to 2020. That ranks it 292 of 395 test families in our census. See the counts for every test.
Show the numbers
| Year | Papers |
|---|---|
| 2025 | 4 |
| 2024 | 9 |
| 2023 | 7 |
| 2022 | 3 |
| 2021 | 9 |
| 2020 | 4 |
| 2019 | 8 |
| 2018 | 9 |
| 2017 | 4 |
| 2016 | 9 |
| 2015 | 10 |
| 2014 | 15 |
| 2013 | 6 |
| 2012 | 7 |
| 2011 | 3 |
| 2010 | 8 |
| 2009 | 5 |
| 2008 | 4 |
| 2007 | 9 |
| 2006 | 10 |
| 2005 | 2 |
| 2004 | 7 |
| 2003 | 4 |
| 2002 | 3 |
| 2001 | 5 |
| 2000 | 3 |
Use grade D
30 to 99 papers from 2021 to 2025.
Evidence grade C
At least 2 test-retest papers, 30 reliability or validity papers or 3 registered clinical studies.
- Papers on test-retest reliability
- 2
- Papers on reliability or validity
- 20
- Registered clinical studies using it as an outcome
- 3
How the grades work
Use: A is 1,000 or more papers from 2021 to 2025, B 300 to 999, C 100 to 299, D 30 to 99 and E fewer than 30. Evidence: A means at least 25 papers report its test-retest reliability and at least 25 registered clinical studies use it as an outcome; B, at least 8 test-retest papers, and either 5 registered clinical studies or 150 reliability or validity papers; C, at least 2 test-retest papers, 30 reliability or validity papers or 3 registered clinical studies; D, little published measurement evidence found. The counts measure use. They include every paper that names the task in its title or abstract. Grades describe the published research on this task, not ConductCognition's version of it.
Source: ConductCognition test census 0.14.0, counted 31 October 2026 from OpenAlex and ClinicalTrials.gov.
Task design
The trial sequence as the test runs in ConductCognition.
- Letters
- Three consonants from B C D F G L M N P R T V Z: those the English and Italian alphabets share, less H, Q and S, which join other consonants into sounds that start words.
- Trigram rules
- Three different letters, never two side by side that are neighbors in the alphabet or that start words in English, Italian, German, Spanish, French or Portuguese, and no common abbreviation. No two trigrams in a row share a letter, and none repeats.
- Trial
- A fixation cross for 1,000 ms, the three letters together for 1,500 ms, then counting back by threes from a three-digit number for the delay, then recall.
- Delays
- 3, 6, 9, 12, 15 and 18 seconds, each once in every block of six trials in a seeded order: four trials at each delay, 24 in all (standard; two to six at each delay).
- Counting
- Start numbers from 301 to 999, never ending in 0. Each number is typed, or tapped on a keypad on touch screens, and is entered at its third digit; the last number entered stays on screen.
- Recall
- The three letters in order, typed or tapped on an on-screen keypad of A to Z with Delete and Submit. Untimed.
- Practice
- Two trials, with delays of 3 and 9 seconds, each followed by the letters shown, the letters entered and the numbers counted.
- Score
- Trigrams recalled with all three letters in order, overall and at each delay; letters in place; counting accuracy and pace.
Peterson and Peterson spoke the letters and the number and had participants count aloud with a metronome at two counts per second. Here they are shown on screen and the count is typed at the participant's own pace. Their syllables came from published English norms; ours are drawn by rule. No published norms are applied.
Quality checks
Each session is marked valid, needs review or invalid, with the reason, before you see its scores.
Scored rows: test-phase recall entries of the scored run, one per trial. Recalling three letters out of 26 has no meaningful chance level, so accuracy is not judged against chance; recall is untimed, so nothing can be missed. Fewer than 90% of the planned trials invalidates. No number counted on more than a quarter of trials, or under half the numbers counted 3 less than the one before (with at least 10 counted), flags the session and withholds the percentile. No trigram correct is flagged. A hidden tab withholds the percentile.
Why these rules
Counting is what keeps the letters from being rehearsed during the delay (Peterson and Peterson 1959), so recall after little or wrong counting does not measure the same thing. Guessing three letters in order from 26 succeeds about once in 17,600 tries, so chance is not meaningful, and a floor score can be a real result. A hidden tab lets the study, delay or response timers run without the participant, so a percentile is withheld after one.
Running this test
Settings you can change
| Setting | Standard | Allowed |
|---|---|---|
| Trials at each delay | 4 | 2 to 6 |
Yearly plans can change settings within these limits. Free and pay-as-you-go studies use the standard settings.
Need a setting this test does not have?
Devices and languages
- Untimed test: runs on desktops, laptops, tablets and phones. Participant devices
- Languages: English, Spanish, French, German, Italian, Portuguese (Brazil), Chinese (Simplified) and Japanese.
- Available on: Every plan, including the free plan.
- Recruiting online? See the setup guides for Prolific, Sona Systems, CloudResearch Connect and Qualtrics.
Cite and describe
Participants completed the Brown-Peterson Task in a web browser (ConductCognition task version 1.0.0, scoring version 1.0.0; Brown, 1958; Peterson and Peterson, 1959), with the standard settings (trials at each delay: 4). The main score was trigrams recalled (share of trigrams entered with all three letters in the order shown, across all delays).
ConductCognition versions: task version 1.0.0, scoring version 1.0.0. Every export records the versions each session used, for a methods section.
- Peterson, L. R., & Peterson, M. J. (1959). Short-term retention of individual verbal items. Journal of Experimental Psychology, 58(3), 193-198. https://doi.org/10.1037/h0049234The method: a consonant trigram, counting back from a three-digit number, and delays of 3 to 18 seconds.
- Brown, J. (1958). Some tests of the decay theory of immediate memory. Quarterly Journal of Experimental Psychology, 10(1), 12-21. https://doi.org/10.1080/17470215808416249Forgetting within seconds when other material follows the items.
- Keppel, G., & Underwood, B. J. (1962). Proactive inhibition in short-term retention of single items. Journal of Verbal Learning and Verbal Behavior, 1(3), 153-161. https://doi.org/10.1016/S0022-5371(62)80023-1Forgetting that grows over the first trials as earlier items interfere.
- Floden, D., Stuss, D. T., & Craik, F. I. M. (2000). Age differences in performance on two versions of the Brown-Peterson task. Aging, Neuropsychology, and Cognition, 7(4), 245-259. https://doi.org/10.1076/anec.7.4.245.795
Source papers
- Peterson LR, Peterson MJ (1959). Short-term retention of individual verbal items. Journal of Experimental Psychology, 58(3):193-198.Paradigm source, Undergraduates
- Keppel G, Underwood BJ (1962). Proactive inhibition in short-term retention of single items. Journal of Verbal Learning and Verbal Behavior, 1(3):153-161.Paradigm source, Adults
Questions
How long does the Brown-Peterson Task take?
About 8 to 11 minutes, as listed in the test library.
What device does a participant need?
Untimed test: runs on desktops, laptops, tablets and phones. The browser must be Chrome, Edge, Firefox or Safari.
What scores does it produce?
Trigrams Recalled, Recall at 3 Seconds, Recall at 6 Seconds, Recall at 9 Seconds, Recall at 12 Seconds, Recall at 15 Seconds, Recall at 18 Seconds, Drop from 3 to 18 Seconds, Letters in Place, Letters Anywhere, First Block Recall, Later Blocks Recall, Counting Accuracy, Seconds per Number, Numbers Counted, Trials Without Counting, Anticipations, Median Entry Time, Trials Completed and Planned Trials. Each session is also marked valid, needs review or invalid, with the reason.
How widely is the Brown-Peterson Task used in research?
32 papers from 2021 to 2025 name it in their title or abstract, down 6% compared with 2016 to 2020. That ranks it 292 of 395 test families in the ConductCognition test census (use grade D). Source: ConductCognition test census 0.14.0, counted 31 October 2026 from OpenAlex and ClinicalTrials.gov.
How much reliability evidence does the Brown-Peterson Task have?
In the published research, 2 papers report its test-retest reliability and 3 registered clinical studies use it as an outcome (evidence grade C in the ConductCognition test census).
Which settings can a researcher change?
Trials at each delay (2 to 6). Settings can be changed on yearly plans; free and pay-as-you-go studies use the standard settings.
Which languages can participants use?
Participants can take this test in English, Spanish, French, German, Italian, Portuguese (Brazil), Chinese (Simplified) and Japanese. English is on every plan, and the other languages come with yearly plans. Have a native speaker read the machine-translated text before launch.
Is this a clinical test?
No. ConductCognition is for research use only. It runs, scores and exports the test; clinical interpretation is outside the platform.
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