Attention
Absolute Identification Task
Also called: absolute judgment task, line-length identification, unidimensional identification
Measure how accurately people identify a line from a learned set of lengths. Participants learn the number for each line, then name it when shown alone.
5-7 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
- 4
- Evidence grade
- D
- Registered clinical studies
- 0
What it measures
Measures how accurately people identify a line's length from a learned set. Participants learn the number for each line, then press its number when it appears alone.
Constructs
- Absolute identification
- Perceptual categorization
- Memory for stimulus magnitude
Research uses
- Perceptual decision research
- Within-study group comparisons
How the paradigm works
Absolute identification measures how accurately a person names a stimulus drawn from a learned set that varies on one dimension. Here that dimension is line length. Participants learn numbered lines, then identify each line shown alone. The task reveals which lengths are confused and whether the endpoints are easier than the middle.
More about the paradigm
This version draws eight lengths, from 40 to 170 CSS pixels, labeled 1 to 8. After a study screen and 16 practice trials, each length appears 12 times in a seeded order: 96 test trials with a break halfway. A line appears for 400 ms after a 500 ms fixation; the number key can be pressed within 4 seconds of line onset. The correct number follows every answer for 600 ms. Researchers can choose six lengths or change the trials per length.
Accuracy is the primary score. The task also reports mean label error, accuracy at the endpoints and in the interior, correct response time, early answers and omissions. Early and missing answers count as incorrect. This is a single-session research measure, with no adaptive training or published norms. Screens differ in physical size, so compare sessions using the same set and display conditions. No screen calibration is required.
Scores
- Identification Accuracy%
- Share of all test trials with the correct number at or after 100 ms and within 4,000 ms.
- Higher means more lengths identified correctly
- Mean Label Errorscore
- Mean absolute difference between the reported and correct number, among timely answers.
- Lower means nearer labels; unit is label steps
- Endpoint Accuracy%
- Accuracy for the shortest and longest lengths.
- Descriptive
- Interior Accuracy%
- Accuracy for the lengths between the endpoints.
- Descriptive
- Mean Correct Response Timems
- Mean time from line onset to a correct, timely answer.
- Descriptive
- Anticipationscount
- Responses under 100 ms from line onset.
- Descriptive
- Missed Answerscount
- Trials with no number-key answer.
- Descriptive
- Test Trialscount
- Scored trials in the selected run.
- Descriptive
Use and evidence
4 papers from 2021 to 2025 name this task in their title or abstract. That ranks it 475 of 495 test families in our census. See the counts for every test.
Show the numbers
| Year | Papers |
|---|---|
| 2025 | 0 |
| 2024 | 0 |
| 2023 | 2 |
| 2022 | 1 |
| 2021 | 1 |
| 2020 | 0 |
| 2019 | 2 |
| 2018 | 1 |
| 2017 | 3 |
| 2016 | 1 |
| 2015 | 3 |
| 2014 | 3 |
| 2013 | 2 |
| 2012 | 2 |
| 2011 | 4 |
| 2010 | 2 |
| 2009 | 7 |
| 2008 | 3 |
| 2007 | 1 |
| 2006 | 2 |
| 2005 | 1 |
| 2004 | 2 |
| 2003 | 0 |
| 2002 | 3 |
| 2001 | 3 |
| 2000 | 2 |
Use grade E
Fewer than 30 papers from 2021 to 2025.
Evidence grade D
Little published measurement evidence found.
- Papers on test-retest reliability
- 0
- Papers on reliability or validity
- 2
- Registered clinical studies using it as an outcome
- 0
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 3 November 2026 from OpenAlex and ClinicalTrials.gov.
Task design
The trial sequence as the test runs in ConductCognition.
- Display
- Eight generated lengths: 40, 49, 61, 74, 92, 113, 139 and 170 CSS pixels on a 280 by 180 px dark panel. A six-length setting uses the first six.
- Trial
- 500 ms fixation, 400 ms line, up to 4,000 ms from line onset to answer, then the correct number for 600 ms.
- Practice
- Study the labeled lengths, then two practice trials per length: 16 with the standard eight lengths.
- Trial mix
- 12 trials per length, 96 test trials as standard, balanced in seeded random order with a break halfway. Settings allow 8, 12 or 16 trials per length.
- Score
- Accuracy over all trials; mean absolute label error among timely answers; endpoint and interior accuracy; correct response time.
Our lengths, keyboard answers and session settings adapt the numbered-line method. This measures identification within a set, without physical-size calibration. Screens differ; keep display conditions consistent. No published norms or clinical cutoffs are applied.
Quality checks
Each session is marked valid, needs review or invalid, with the reason, before you see its scores.
Scored rows: absolute_identification_test from the scored run. Number keys identify one of six or eight equally frequent lengths within 4,000 ms; correctness is recomputed from the number. Below chance invalidates and not above chance is flagged. Repeated answers, missed responses and responses under 100 ms follow the timed-test rule.
Why these rules
Accuracy significantly below chance (one-sided exact test, p < .05) cannot come from guessing; it means the response mapping was reversed or the task was not followed (Slick, Sherman and Iverson 1999 treat below-chance forced-choice performance as definite response bias). Chance-level accuracy can be a real result in impaired participants, so it is only flagged. One option on at least 90% of answered trials, when the correct options are balanced and accuracy is not above chance, means the answers did not depend on the items (the task counterpart of long-string responding in surveys; Curran 2016). Missed responses and responses under 100 ms keep the platform's timed-test rule: more than max(3, 25%) missed responses or more than max(2, 20%) responses under 100 ms invalidate, and any is flagged. A response under 100 ms cannot be a reaction to the stimulus.
No percentile. Scores and quality flags only.
Running this test
Settings you can change
| Setting | Standard | Allowed |
|---|---|---|
| Number of lengths | 8 (standard) | 6, 8 (standard) |
| Trials per length | 12 (standard) | 8, 12 (standard), 16 |
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 Absolute Identification Task in a web browser (ConductCognition task version 1.0.0, scoring version 1.0.0; Elvevåg et al., 2004), with the standard settings (number of lengths: 8; trials per length: 12). The main score was identification accuracy (share of all test trials with the correct number at or after 100 ms and within 4,000 ms).
ConductCognition versions: task version 1.0.0, scoring version 1.0.0. Every export records the versions each session used, for a methods section.
- Elvevåg, B., Brown, G. D. A., McCormack, T., Vousden, J. I., & Goldberg, T. E. (2004). Identification of tone duration, line length, and letter position: An experimental approach to timing and working memory deficits in schizophrenia. Journal of Abnormal Psychology, 113(4), 509-521. https://doi.org/10.1037/0021-843X.113.4.509Experiment 2: single line presentations after learning numbered lengths, with label feedback.
Source papers
- Elvevåg, B., Brown, G. D. A., McCormack, T., Vousden, J. I., & Goldberg, T. E. (2004). Identification of tone duration, line length, and letter position: An experimental approach to timing and working memory deficits in schizophrenia. Journal of Abnormal Psychology, 113(4), 509-521.Paradigm source, Adults
Questions
How long does the Absolute Identification Task take?
About 5 to 7 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?
Identification Accuracy, Mean Label Error, Endpoint Accuracy, Interior Accuracy, Mean Correct Response Time, Anticipations, Missed Answers and Test Trials. Each session is also marked valid, needs review or invalid, with the reason.
How widely is the Absolute Identification Task used in research?
4 papers from 2021 to 2025 name it in their title or abstract. That ranks it 475 of 495 test families in the ConductCognition test census (use grade E). Source: ConductCognition test census 0.22.0, counted 3 November 2026 from OpenAlex and ClinicalTrials.gov.
How much reliability evidence does the Absolute Identification Task have?
In the published research, 0 papers report its test-retest reliability and 0 registered clinical studies use 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?
Number of lengths (6, 8 (standard)) and trials per length (8, 12 (standard), 16). 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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