Attention
Immediate and Delayed Memory Task
Also called: immediate memory task, IMT, DMT, IMT ratio, commission error ratio
Measure impulsive responding in a stream of five-digit numbers: participants press for exact repeats and hold back when one digit changed, scored as commission errors over correct detections.
10-12 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. Preview any test free after you sign up.
- Papers, 2021 to 2025
- 33
- Evidence grade
- C
- Registered clinical studies
- 10
What it measures
Measures impulsive responding and attention in a stream of five-digit numbers. Participants press the spacebar when a number repeats the one they compare it with, the number just before it or, in the delayed part, the last one before three showings of 12345, and hold back when only one digit changed. The main score is commission errors divided by correct detections in the immediate part.
Constructs
- Impulsive responding
- Sustained attention
- Holding a number over a short delay
- Response inhibition
Research uses
- Impulsivity research
- Psychopharmacology and substance use studies
- Repeated testing within a study
- Within-study group comparison
How the paradigm works
The immediate and delayed memory task measures impulsive responding and attention with a stream of five-digit numbers (Dougherty, Marsh and Mathias, 2002). Each number shows for 500 ms, one each second. Participants press the spacebar when a number is exactly the same as the number they compare it with. In the immediate part, that is the number just before it. In the delayed part, the number 12345 appears three times between the numbers to compare, so a number has to be held for 3.5 seconds while 12345 is ignored. A third of the numbers to compare are repeats, a third are catch numbers that change one digit, and the rest are new numbers. Every number is drawn by our code from the session's seed.
More about the paradigm
The standard session runs one 4-minute block of each part, immediate first, each after practice with feedback, about 11 minutes in all. A study can set blocks of 3 to 5 minutes and one or two blocks of each part; with two, the parts alternate with 30 seconds of rest, as in the source's sessions of two 5-minute blocks of each part.
The main score is the immediate commission ratio: commission errors, presses for catch numbers, divided by correct detections, presses for repeats. Higher ratios mean more impulsive responding (Dougherty et al., 2009). The delayed ratio, the hit, commission and filler error rates, discriminability (A') and response bias (B''D) between repeats and catch numbers, and the response times of correct detections and commission errors are reported for each part. Presses under 100 ms are counted as anticipations. Scores support research and do not diagnose.
Scores
- Immediate Commission Ratioscore
- Commission errors divided by correct detections in the immediate part: presses for catch numbers over presses for repeats.
- Higher means more impulsive responding
- Delayed Commission Ratioscore
- Commission errors divided by correct detections in the delayed part.
- Higher means more impulsive responding
- Immediate Hit Rate%
- Share of repeated numbers pressed for at or after 100 ms in the immediate part.
- Higher is better
- Immediate Commission Rate%
- Share of catch numbers, which changed one digit, pressed for in the immediate part.
- Lower is better
- Immediate Filler Error Rate%
- Share of new numbers pressed for in the immediate part.
- Lower is better
- Delayed Hit Rate%
- Share of repeated numbers pressed for at or after 100 ms in the delayed part.
- Higher is better
- Delayed Commission Rate%
- Share of catch numbers pressed for in the delayed part.
- Lower is better
- Delayed Filler Error Rate%
- Share of new numbers pressed for in the delayed part.
- Lower is better
- Immediate Discriminability (A')score
- Nonparametric A' between repeats and catch numbers in the immediate part, from rates with the log-linear correction. 0.5 is chance and 1 is perfect.
- Higher means repeats were better told apart from catch numbers
- Delayed Discriminability (A')score
- Nonparametric A' between repeats and catch numbers in the delayed part.
- Higher means repeats were better told apart from catch numbers
- Immediate Response Bias (B''D)score
- B''D between repeats and catch numbers in the immediate part, from -1 to 1, from rates with the log-linear correction.
- Positive values mean cautious pressing, negative values liberal pressing
- Delayed Response Bias (B''D)score
- B''D between repeats and catch numbers in the delayed part.
- Positive values mean cautious pressing, negative values liberal pressing
- Immediate Correct Detection Timems
- Mean response time of correct detections in the immediate part, from the number's onset.
- Lower is faster
- Immediate Commission Error Timems
- Mean response time of commission errors in the immediate part.
- Informational
- Delayed Correct Detection Timems
- Mean response time of correct detections in the delayed part.
- Lower is faster
- Delayed Commission Error Timems
- Mean response time of commission errors in the delayed part.
- Informational
- Presses During 12345count
- Presses while the distractor 12345 was showing in the delayed part.
- Lower is better
- Anticipationscount
- Presses under 100 ms from a number's onset. They count as none of the other responses.
- Lower is better
- Immediate Correct Detectionscount
- Repeats pressed for at or after 100 ms in the immediate part.
- Informational
- Immediate Commission Errorscount
- Catch numbers pressed for at or after 100 ms in the immediate part.
- Lower is better
- Delayed Correct Detectionscount
- Repeats pressed for at or after 100 ms in the delayed part.
- Informational
- Delayed Commission Errorscount
- Catch numbers pressed for at or after 100 ms in the delayed part.
- Lower is better
- Immediate Repeatstrials
- Repeated numbers shown in the immediate part.
- Informational
- Immediate Catch Numberstrials
- Catch numbers shown in the immediate part.
- Informational
- Immediate New Numberstrials
- New numbers shown in the immediate part, not counting the first number of a block.
- Informational
- Delayed Repeatstrials
- Repeated numbers shown in the delayed part.
- Informational
- Delayed Catch Numberstrials
- Catch numbers shown in the delayed part.
- Informational
- Delayed New Numberstrials
- New numbers shown in the delayed part, not counting the first number of a block.
- Informational
- Planned Numberstrials
- Numbers to compare that the session planned to show, first numbers of blocks included.
- Informational
- Total Numberstrials
- Numbers to compare in the scored run, first numbers of blocks included.
- Under 90% of the planned numbers is invalid
Use and evidence
33 papers from 2021 to 2025 name this task in their title or abstract, down 3% compared with 2016 to 2020. That ranks it 289 of 395 test families in our census. See the counts for every test.
Show the numbers
| Year | Papers |
|---|---|
| 2025 | 10 |
| 2024 | 4 |
| 2023 | 7 |
| 2022 | 3 |
| 2021 | 9 |
| 2020 | 8 |
| 2019 | 4 |
| 2018 | 7 |
| 2017 | 1 |
| 2016 | 14 |
| 2015 | 7 |
| 2014 | 9 |
| 2013 | 9 |
| 2012 | 6 |
| 2011 | 7 |
| 2010 | 6 |
| 2009 | 5 |
| 2008 | 3 |
| 2007 | 6 |
| 2006 | 1 |
| 2005 | 6 |
| 2004 | 7 |
| 2003 | 6 |
| 2002 | 11 |
| 2001 | 1 |
| 2000 | 4 |
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
- 1
- Papers on reliability or validity
- 17
- Registered clinical studies using it as an outcome
- 10
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.
- Numbers
- Five-digit numbers drawn by our code from the session's seed, each for 500 ms, one every 1,000 ms, at the center of the screen.
- Number types
- After a first number with nothing to compare, a third are repeats, a third are catch numbers that change one digit, at a random place to a random digit, and the rest are new numbers.
- Immediate part
- Press the spacebar when a number is the same as the number just before it.
- Delayed part
- 12345 shows 3 times between the numbers to compare, so the comparison spans 3,500 ms; participants ignore 12345.
- Blocks
- One 4-minute block of each part (standard; 3 to 5 minutes and 1 or 2 blocks of each part), immediate first. With 2, the parts alternate with 30 seconds of rest.
- Key
- The spacebar. A press does not end the trial, and a press under 100 ms is an anticipation.
- Practice
- 15 immediate numbers and 8 delayed numbers, with feedback after each. No feedback in the test.
Dougherty and colleagues ran two 5-minute blocks of each part, about 20 minutes, answered with a mouse button. The standard here runs one 4-minute block of each, near 11 minutes with practice, and the settings reach their session. Every number is drawn by our code; no software from that lab is used. The 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.
Scored rows: immediate_delayed_memory_test from the scored run, press on a repeated number (a third of the numbers compared) and withhold on catch numbers and new numbers; the first number of each block is not scored. Fewer than 90% of the planned numbers or an immediate-part hit rate under 25% invalidates; an immediate-part hit rate under 50% or a filler error rate over 20% is flagged and withholds the percentile. Responding mainly on numbers that needed no press invalidates; not separating repeats from other numbers is flagged. A run of misses covering half the repeats (minimum 8) is flagged and withholds the percentile. Responses under 100 ms follow the timed-test rule.
Why these rules
Responses concentrated on trials that needed none (one-sided Fisher exact test, p < .05) mean the instructions were reversed and invalidate; responses that do not separate the two trial types are flagged. Missed targets are what this test measures, so missed responses never invalidate on their own. A session with no responses is invalid. An unbroken run of misses covering at least half the response trials (minimum 8) may mean the participant stopped, so the session is flagged and its percentile withheld. The commission ratio divides by correct detections, so it is unstable when few repeats were found, and many presses for new numbers mean the numbers were not compared. The limits are ConductScience choices: the source papers report the ratio but set no exclusion limits. Responses under 100 ms follow the timed-test rule.
Running this test
Settings you can change
| Setting | Standard | Allowed |
|---|---|---|
| Block length (minutes) | 4 | 3 to 5 |
| Blocks of each part | 1 | 1 to 2 |
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.
- Recruiting online? See the setup guides for Prolific, Sona Systems, CloudResearch Connect and Qualtrics.
Cite and describe
Participants completed the Immediate and Delayed Memory Task in a web browser (ConductCognition task version 1.0.0, scoring version 1.0.0; Dougherty, Marsh and Mathias, 2002; Dougherty et al., 2000), with the standard settings (block length (minutes): 4; blocks of each part: 1). The main score was immediate commission ratio (commission errors divided by correct detections in the immediate part: presses for catch numbers over presses for repeats).
ConductCognition versions: task version 1.0.0, scoring version 1.0.0. Every export records the versions each session used, for a methods section.
- Dougherty, D. M., Marsh, D. M., & Mathias, C. W. (2002). Immediate and delayed memory tasks: A computerized behavioral measure of memory, attention, and impulsivity. Behavior Research Methods, Instruments, & Computers, 34(3), 391-398. https://doi.org/10.3758/BF03195467
- Dougherty, D. M., Marsh, D. M., Moeller, F. G., Chokshi, R. V., & Rosen, V. C. (2000). Effects of moderate and high doses of alcohol on attention, impulsivity, discriminability, and response bias in immediate and delayed memory task performance. Alcoholism: Clinical and Experimental Research, 24(11), 1702-1711. https://doi.org/10.1111/j.1530-0277.2000.tb01972.xCatch numbers, the 3.5 second delay, discriminability and response bias.
- Dougherty, D. M., Mathias, C. W., Marsh-Richard, D. M., Furr, R. M., Nouvion, S. O., & Dawes, M. A. (2009). Distinctions in behavioral impulsivity: Implications for substance abuse research. Addictive Disorders & Their Treatment, 8(2), 61-73. https://doi.org/10.1097/ADT.0b013e318172e488The shares of the number types, alternating 5-minute blocks with 30 seconds of rest, and the ratio of commission errors to correct detections.
- Donaldson, W. (1992). Measuring recognition memory. Journal of Experimental Psychology: General, 121(3), 275-277. https://doi.org/10.1037/0096-3445.121.3.275The response bias index B''D.
- Stanislaw, H., & Todorov, N. (1999). Calculation of signal detection theory measures. Behavior Research Methods, Instruments, & Computers, 31(1), 137-149. https://doi.org/10.3758/BF03207704The formulas for A' and B''D.
- Hautus, M. J. (1995). Corrections for extreme proportions and their biasing effects on estimated values of d'. Behavior Research Methods, Instruments, & Computers, 27(1), 46-51. https://doi.org/10.3758/BF03203619
Source papers
- Dougherty DM, Marsh DM, Mathias CW (2002). Immediate and delayed memory tasks: a computerized behavioral measure of memory, attention, and impulsivity. Behavior Research Methods, Instruments, & Computers, 34(3):391-398.Paradigm source, Adults
Questions
How long does the Immediate and Delayed Memory Task take?
About 10 to 12 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?
Immediate Commission Ratio, Delayed Commission Ratio, Immediate Hit Rate, Immediate Commission Rate, Immediate Filler Error Rate, Delayed Hit Rate, Delayed Commission Rate, Delayed Filler Error Rate, Immediate Discriminability (A'), Delayed Discriminability (A'), Immediate Response Bias (B''D), Delayed Response Bias (B''D), Immediate Correct Detection Time, Immediate Commission Error Time, Delayed Correct Detection Time, Delayed Commission Error Time, Presses During 12345, Anticipations, Immediate Correct Detections, Immediate Commission Errors, Delayed Correct Detections, Delayed Commission Errors, Immediate Repeats, Immediate Catch Numbers, Immediate New Numbers, Delayed Repeats, Delayed Catch Numbers, Delayed New Numbers, Planned Numbers and Total Numbers. Each session is also marked valid, needs review or invalid, with the reason.
How widely is the Immediate and Delayed Memory Task used in research?
33 papers from 2021 to 2025 name it in their title or abstract, down 3% compared with 2016 to 2020. That ranks it 289 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 Immediate and Delayed Memory Task have?
In the published research, 1 paper reports its test-retest reliability and 10 registered clinical studies use it as an outcome (evidence grade C in the ConductCognition test census).
Which settings can a researcher change?
Block length (minutes) (3 to 5) and blocks of each part (1 to 2). 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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