Processing speed
Letter Matching Task
Also called: name identity task, physical identity task, Posner letter matching paradigm, cross-case letter matching
Measure how quickly people recognize a letter across cases. Participants judge pairs such as A A and A a as the same letter, with response times and accuracy reported.
4-6 minTimed: desktop or laptop with a mouse or trackpad
Free to start: 10 free participants per account, then $0.99 per participant for academic research, or any yearly plan. Try it here first, with no account.
- Papers, 2021 to 2025
- 6
- Evidence grade
- D
- Registered clinical studies
- 1
Same letter?
What it measures
Measures the extra time needed to recognize the same letter across cases. Participants judge whether two visible letters have the same name, comparing identical pairs such as A A with cross-case pairs such as A a. Scores the difference in correct response times, with accuracy for each kind of pair.
Constructs
- Letter identification
- Visual and name matching
- Processing speed
Research uses
- Letter recognition research
- Reading and processing-speed studies
- Within-study group comparison
How the paradigm works
The Letter Matching Task measures the extra time needed to recognize a letter across upper and lower case. Two letters appear together. A participant presses one key for the same letter name and the other for different names. Identical matches (A A) and cross-case matches (A a) therefore require the same answer, and their difference in correct response times gives the cross-case cost.
More about the paradigm
The task follows the name-identity condition of Posner and Mitchell (1967). Here 8 practice pairs with feedback precede 96 test pairs, with equal numbers of identical matches, cross-case matches, same-case nonmatches and mixed-case nonmatches. The session seed draws the pair order and key mapping. Six Latin letters with distinct uppercase and lowercase shapes are used in every language. Participants need familiarity with those letters.
Scores
- Cross-case Costms
- Mean correct time for cross-case matches minus identical matches.
- Positive means cross-case matches took longer; compare groups.
- Identical Match Timems
- Mean correct response time for identical letters.
- Lower means faster.
- Cross-case Match Timems
- Mean correct response time for the same letter in different cases.
- Lower means faster.
- Different-letter Timems
- Mean correct response time for different letter names.
- Lower means faster.
- Accuracy%
- Correct responses at or after 100 ms divided by all test pairs.
- Read alongside response times.
- Identical Match Accuracy%
- Correct share of identical-letter pairs.
- Higher means more correct responses.
- Cross-case Match Accuracy%
- Correct share of cross-case same-letter pairs.
- Higher means more correct responses.
- Smallest Match Samplecount
- The smaller number of usable correct responses in the two match conditions.
- At least five are required in each condition.
- Missed Responsescount
- Pairs without a response before the deadline.
- Lower means fewer missed responses.
- Anticipationscount
- Responses under 100 ms, excluded from correct times.
- Lower means fewer early responses.
- Completed Trialscount
- Test pairs recorded in the selected run.
- At least 90% of planned pairs are required.
- Planned Trialscount
- Number of test pairs set for the run.
- Describes the session length.
Use and evidence
6 papers from 2021 to 2025 name this task in their title or abstract. That ranks it 471 of 495 test families in our census. See the counts for every test.
Show the numbers
| Year | Papers |
|---|---|
| 2025 | 1 |
| 2024 | 1 |
| 2023 | 1 |
| 2022 | 3 |
| 2021 | 0 |
| 2020 | 1 |
| 2019 | 0 |
| 2018 | 2 |
| 2017 | 0 |
| 2016 | 2 |
| 2015 | 1 |
| 2014 | 2 |
| 2013 | 3 |
| 2012 | 0 |
| 2011 | 0 |
| 2010 | 3 |
| 2009 | 4 |
| 2008 | 1 |
| 2007 | 3 |
| 2006 | 4 |
| 2005 | 10 |
| 2004 | 4 |
| 2003 | 5 |
| 2002 | 0 |
| 2001 | 5 |
| 2000 | 5 |
Use grade E
Fewer than 30 papers from 2021 to 2025.
Evidence grade D
Little published measurement evidence found.
- Papers on test-retest reliability
- 1
- Papers on reliability or validity
- 13
- Registered clinical studies using it as an outcome
- 1
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 0.22.0, counted 2 November 2026 from OpenAlex and ClinicalTrials.gov.
Task design
The trial sequence as the test runs in ConductCognition.
- Letters
- A, B, D, E, G and R in upper and lower case, shown together in the same font. The letter names must be familiar.
- Session
- 8 practice pairs with feedback, then 96 test pairs without feedback. Set 48 to 192 test pairs, rounded to a multiple of four.
- Balance
- Four equally frequent kinds: identical matches, cross-case matches, same-case nonmatches and mixed-case nonmatches. The seed draws order and F/J key mapping.
- Timing
- 500 ms fixation, up to 3,000 ms to respond, then a 200 ms gap. Practice feedback lasts 800 ms.
- Scores
- Mean correct cross-case match time minus identical-match time, both component means, different-letter time and accuracy. Responses under 100 ms are anticipations. At least five correct responses per match condition and 90% completion are required.
This is a short, fixed-timing version of the name-identity task. The original studies used days of practice and longer intertrial intervals. A cross-case difference reflects the combined demands of recognizing different letter forms; compare groups alongside accuracy. No published norms are applied; scores support research and do not diagnose.
Quality checks
Each session is marked valid, needs review or invalid, with the reason, before you see its scores.
Scores test pairs from the run with the most responses, ties going to the latest run. Chance is 1 in 2. At least five correct responses in each match condition and 90% of planned trials are needed. Missed responses and responses under 100 ms follow the timed-test rule.
Why these rules
An effect needs both correct-match means. The minimum of five observations per match condition and 90% completion are ConductScience quality rules. Answers under 100 ms cannot reflect a judgment of the pair. A hidden tab withholds the percentile.
No percentile. Scores and quality flags only.
Running this test
Settings you can change
| Setting | Standard | Allowed |
|---|---|---|
| Test trials | 96 | 48 to 192 |
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
- Timed test: participants need a desktop or laptop with a mouse or trackpad. Participant devices
- Languages: English, Spanish, French, German, Italian, Portuguese (Brazil), Chinese (Simplified) and Japanese.
- Available on: Every plan, including the free plan.
- No percentile. Scores and quality flags only. How norms work
- Recruiting online? See the setup guides for Prolific, Sona Systems, CloudResearch Connect and Qualtrics.
Cite and describe
Participants completed the Letter Matching Task in a web browser (ConductCognition task version 1.0.0, scoring version 1.0.0; Posner & Mitchell, 1967), with the standard settings (test trials: 96). The main score was cross-case cost (mean correct time for cross-case matches minus identical matches).
ConductCognition versions: task version 1.0.0, scoring version 1.0.0. Every export records the versions each session used, for a methods section.
- Posner, M. I., & Mitchell, R. F. (1967). Chronometric analysis of classification. Psychological Review, 74(5), 392-409. https://doi.org/10.1037/h0024913
Source papers
- Posner MI, Mitchell RF (1967). Chronometric analysis of classification. Psychological Review, 74(5):392-409.Paradigm source, Adults
Questions
How long does the Letter Matching Task take?
About 4 to 6 minutes, as listed in the test library.
What device does a participant need?
Timed test: participants need a desktop or laptop with a mouse or trackpad. The browser must be Chrome, Edge, Firefox or Safari.
What scores does it produce?
Cross-case Cost, Identical Match Time, Cross-case Match Time, Different-letter Time, Accuracy, Identical Match Accuracy, Cross-case Match Accuracy, Smallest Match Sample, Missed Responses, Anticipations, Completed Trials and Planned Trials. Each session is also marked valid, needs review or invalid, with the reason.
How widely is the Letter Matching Task used in research?
6 papers from 2021 to 2025 name it in their title or abstract. That ranks it 471 of 495 test families in the ConductCognition test census (use grade E). Source: ConductCognition test census 0.22.0, counted 2 November 2026 from OpenAlex and ClinicalTrials.gov.
How much reliability evidence does the Letter Matching Task have?
In the published research, 1 paper reports its test-retest reliability and 1 registered clinical study uses it as an outcome (evidence grade D in the ConductCognition test census).
Does it report a percentile?
No. Scores and quality flags only.
Which settings can a researcher change?
Test trials (48 to 192). 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.
Every test: the full test list.
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