Working Memory
Letter-Number Sequencing Task
Also called: LNS, letter-number span, LN span
Measure working memory with mixed runs of numbers and letters, entered as numbers in ascending order and then letters in alphabetical order.
5-8 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
- 162
- Evidence grade
- B
- Registered clinical studies
- 184
What it measures
Measures working memory with mixed runs of numbers and letters. Participants see each run one item at a time, then enter the numbers in ascending order followed by the letters in alphabetical order.
Constructs
- Working memory
- Mental reordering
- Verbal short-term memory
- Sequencing
Research uses
- Working memory research in schizophrenia and other clinical groups
- Aging and cognitive change studies
- Individual-difference studies of working memory
How the paradigm works
The letter-number sequencing task measures working memory: holding a short mixed list in mind and putting it in a new order. On each run, numbers and letters appear one at a time at the center of the screen. The participant then enters the numbers from smallest to largest, followed by the letters in alphabetical order, by typing or by tapping an on-screen keypad. Seeing 7 C 2 A, the answer is 2 7 A C.
More about the paradigm
The task follows the letter-number span of Gold and colleagues (1997), introduced to study auditory working memory in schizophrenia. Runs grow from 2 to 8 items, with three runs at each length and one item per second. The test stops after a length at which every run was entered wrongly. Two practice runs, of 2 and 3 items, show the correct answer. Settings give one to four runs at each length, turn the stop rule off, or change the time per item from 500 to 2,000 ms. Entry is untimed.
Every run is drawn from the session's seed. The items are the digits 1 to 9 and 15 letters that the English and Italian alphabets share, leaving out B, G, I, O, S and Z, which are easily mistaken for digits. Each run is half digits and half letters, with no item twice, never more than two of a kind in a row, and never already in answer order. No run spells a word or common abbreviation on a stated block list of English and Italian words.
Gold and colleagues read the items aloud; here they are shown on screen. Lists that are heard are usually recalled a little better than lists that are seen, mostly at the last items (Penney 1989), so scores may run slightly lower than with spoken items. In 102 undergraduates, Crowe (2000) found that the task shared most of its variance with digit span forward and backward, with smaller parts from processing speed and visuospatial working memory.
The main score is the number of runs entered correctly, 0 to 21 at the standard settings. The longest length entered correctly, errors by type (a wrong item, letters before digits, or the right items in the wrong order) and entry times are also reported. Scores support research and do not diagnose.
Scores
- Runs Correctcount
- Runs entered correctly: the digits in ascending order, then the letters in alphabetical order (0 to 21 at the standard settings).
- Higher is better
- Longest Spancount
- The longest run length, in items, entered correctly at least once (0 when none was).
- Higher is better
- Proportion Correct%
- Runs entered correctly out of the runs given.
- Higher is better
- Runs Givencount
- Test runs given before the test ended (21 at the standard settings without the stop rule).
- Informational
- Wrong-Item Errorscount
- Entries that do not hold exactly the items shown: an item missing, added or changed.
- Lower is better
- Letters-First Errorscount
- Entries with the right items but a letter before a digit.
- Lower is better
- Order Errorscount
- Entries with the right items, digits first, but the digits not ascending or the letters not in alphabetical order.
- Lower is better
- Median Entry Timems
- Median time from the entry screen to Submit, over all runs.
- Informational
- Median Entry Time, Correct Runsms
- Median time from the entry screen to Submit, over runs entered correctly.
- Informational
Use and evidence
162 papers from 2021 to 2025 name this task in their title or abstract, down 15% compared with 2016 to 2020. That ranks it 144 of 395 test families in our census. See the counts for every test.
Show the numbers
| Year | Papers |
|---|---|
| 2025 | 33 |
| 2024 | 25 |
| 2023 | 40 |
| 2022 | 25 |
| 2021 | 39 |
| 2020 | 40 |
| 2019 | 41 |
| 2018 | 37 |
| 2017 | 36 |
| 2016 | 36 |
| 2015 | 41 |
| 2014 | 29 |
| 2013 | 22 |
| 2012 | 23 |
| 2011 | 26 |
| 2010 | 15 |
| 2009 | 23 |
| 2008 | 25 |
| 2007 | 14 |
| 2006 | 12 |
| 2005 | 3 |
| 2004 | 6 |
| 2003 | 6 |
| 2002 | 5 |
| 2001 | 5 |
| 2000 | 8 |
Use grade C
100 to 299 papers from 2021 to 2025.
Evidence grade B
At least 8 test-retest papers, and either 5 registered clinical studies or 150 reliability or validity papers.
- Papers on test-retest reliability
- 8
- Papers on reliability or validity
- 78
- Registered clinical studies using it as an outcome
- 184
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.
- Items
- Digits 1 to 9 and the letters A C D E F H L M N P Q R T U V: the letters the English and Italian alphabets share, less B, G, I, O, S and Z, which are easily mistaken for digits.
- Runs
- Three runs at each length from 2 to 8 items, 21 in all (standard; one to four at each length), shortest first.
- Run rules
- Half digits and half letters (an odd length has one extra of either), no item twice, never more than two digits or two letters in a row, and never already in answer order. No run spells a word or abbreviation on a block list of English and Italian words and common abbreviations.
- Display
- One item at a time at the center of the screen, one per second (standard; 500 to 2,000 ms), with a 200 ms blank before the next. A fixation cross shows for 1,000 ms before each run.
- Entry
- The digits in ascending order, then the letters in alphabetical order, typed or tapped on an on-screen keypad with Delete and Submit. Untimed.
- Stop rule
- The test ends after a length at which every run was entered wrongly (standard; can be turned off).
- Practice
- Runs of 2 and 3 items, each followed by the correct answer.
Gold and colleagues read the items aloud. Here they are shown on screen. Lists that are heard are usually recalled a little better than lists that are seen, mostly at the last items, so scores may run slightly lower than with spoken items. 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 entries of the scored run, one per run. A run has no meaningful chance level, so accuracy is not judged against chance; entry is untimed, so nothing can be missed. Entering no run correctly is flagged. A hidden tab withholds the percentile.
Why these rules
A random entry of a run's items matches the answer with probability 1 in the number of orders of its items (1 in 2 for 2 items, 1 in 40,320 for 8), 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 |
|---|---|---|
| Runs at each length | 3 | 1 to 4 |
| Stop after a missed length | On | On or off |
| Time per item (ms) | 1,000 | 500 to 2,000 |
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 Letter-Number Sequencing Task in a web browser (ConductCognition task version 1.0.0, scoring version 1.0.0; Gold et al., 1997), with the standard settings (runs at each length: 3; stop after a missed length: On; time per item (ms): 1,000). The main score was runs correct (runs entered correctly: the digits in ascending order, then the letters in alphabetical order (0 to 21 at the standard settings)).
ConductCognition versions: task version 1.0.0, scoring version 1.0.0. Every export records the versions each session used, for a methods section.
- Gold, J. M., Carpenter, C., Randolph, C., Goldberg, T. E., & Weinberger, D. R. (1997). Auditory working memory and Wisconsin Card Sorting Test performance in schizophrenia. Archives of General Psychiatry, 54(2), 159-165. https://doi.org/10.1001/archpsyc.1997.01830140071013
- Crowe, S. F. (2000). Does the letter number sequencing task measure anything more than digit span? Assessment, 7(2), 113-117. https://doi.org/10.1177/107319110000700202What the task shares with digit span forward and backward.
- Penney, C. G. (1989). Modality effects and the structure of short-term verbal memory. Memory & Cognition, 17(4), 398-422. https://doi.org/10.3758/BF03202613Why items that are seen may be recalled a little less well than items that are heard.
Source papers
- Gold JM, Carpenter C, Randolph C, Goldberg TE, Weinberger DR (1997). Auditory working memory and Wisconsin Card Sorting Test performance in schizophrenia. Archives of General Psychiatry, 54(2):159-165.Paradigm source, Adults
- Crowe SF (2000). Does the letter number sequencing task measure anything more than digit span? Assessment, 7(2):113-117.Paradigm source, Undergraduates
- Penney CG (1989). Modality effects and the structure of short-term verbal memory. Memory & Cognition, 17(4):398-422.Paradigm source, Adults
Questions
How long does the Letter-Number Sequencing Task take?
About 5 to 8 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?
Runs Correct, Longest Span, Proportion Correct, Runs Given, Wrong-Item Errors, Letters-First Errors, Order Errors, Median Entry Time and Median Entry Time, Correct Runs. Each session is also marked valid, needs review or invalid, with the reason.
How widely is the Letter-Number Sequencing Task used in research?
162 papers from 2021 to 2025 name it in their title or abstract, down 15% compared with 2016 to 2020. That ranks it 144 of 395 test families in the ConductCognition test census (use grade C). Source: ConductCognition test census 0.14.0, counted 31 October 2026 from OpenAlex and ClinicalTrials.gov.
How much reliability evidence does the Letter-Number Sequencing Task have?
In the published research, 8 papers report its test-retest reliability and 184 registered clinical studies use it as an outcome (evidence grade B in the ConductCognition test census).
Which settings can a researcher change?
Runs at each length (1 to 4), stop after a missed length (On or off) and time per item (ms) (500 to 2,000). 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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