Attention
Lateralization Task
Also called: interaural time difference discrimination, ITD threshold task, interaural level difference discrimination, ILD threshold task, ITD sensitivity, binaural lateralization, left-right lateralization task
Measure the smallest time and level differences between the ears that move a sound inside the head: two sounds through headphones, then which way the sound moved, on two staircases.
7-9 minUntimed
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
- 88
- Evidence grade
- C
- Registered clinical studies
- 3
What it measures
Measures how small a difference between the two ears a listener can follow: a sound reaching one ear microseconds sooner, or a fraction of a decibel louder, moves it to that side inside the head. Each trial plays two sounds through headphones and participants say which way the sound moved; two staircases find the time and level thresholds. Needs headphones and normal hearing; results are research measures, not a hearing test.
Constructs
- Sound lateralization
- Binaural hearing
- Interaural time difference sensitivity
- Interaural level difference sensitivity
Research uses
- Spatial and binaural hearing research
- Auditory perception research
- Within-study group comparison
How the paradigm works
Lateralization over headphones: a sound that reaches one ear a few microseconds sooner, or is a fraction of a decibel louder there, is heard inside the head toward that ear. The smallest interaural time and level differences a listener can follow are classic measures of binaural hearing (Klumpp and Eady, 1956; Yost, 1974; Yost and Dye, 1988). This task measures both as Ochi, Yamasoba and Furukawa (2014) did: each trial plays two sounds, the first with half the difference toward one side and the second with half toward the other, and the listener says which way the sound moved.
More about the paradigm
Set a comfortable volume and complete the 6-trial headphone check, then the left-right check: a tone in one ear at a time, four trials, with a second round after an error. A failed check stops the task by default; researchers can choose to continue with a quality flag.
Two sounds of 400 ms with 100 ms raised-cosine ramps that start and end together in both ears, 200 ms apart: noise from 100 to 4,000 Hz, new for every sound (the standard), or a 500 Hz tone, 10 dB below the volume-setting tone. The time difference is made in the frequency domain, exact to a fraction of a sample; the level difference is split between the ears. Choose Left or Right with no time limit.
Two staircases, time and level, interleaved in a seeded order, 60 trials each (30 to 80 as a setting): 120 scored trials. Two right answers in a row make the difference smaller and one error makes it larger, which tracks 70.7 percent right (Levitt, 1971). Time starts at 200 µs and moves by a factor of 10^0.2 until the fourth turnpoint, then 10^0.05, between 2 and 796 µs; level starts at 6 dB and moves by 1 dB, then 0.25 dB, between 0.25 and 12 dB.
4 practice trials at 600 µs and 10 dB, the sound moving each way once on each staircase, with feedback for 1,000 ms. Scored trials give no feedback.
Each threshold is the mean of the last eight turnpoints after the first four, geometric for time, as Ochi and colleagues computed theirs. Also reported: the share right and the turnpoints on each staircase, the share of Right answers, response time and completed trials. Responses under 100 ms from the answer buttons opening leave the staircase where it was.
Scores
- ITD Thresholdµs
- The difference in arrival time between the ears, from the first sound to the second, that the listener follows on about 71 percent of trials: the geometric mean of the last eight turnpoints after the first four.
- Lower means a smaller time difference was heard to move the sound; not a hearing level
- ILD ThresholddB
- The difference in level between the ears, from the first sound to the second, that the listener follows on about 71 percent of trials: the mean of the last eight turnpoints after the first four.
- Lower means a smaller level difference was heard to move the sound; not a hearing level
- Time Staircase Accuracy%
- Share of time-difference trials answered with the way the sound moved.
- Near 0.71 is expected on a staircase; near 0.5 means the moves were not heard
- Level Staircase Accuracy%
- Share of level-difference trials answered with the way the sound moved.
- Near 0.71 is expected on a staircase; near 0.5 means the moves were not heard
- Time Staircase Turnpointscount
- Times the time staircase changed direction.
- A threshold needs at least eight
- Level Staircase Turnpointscount
- Times the level staircase changed direction.
- A threshold needs at least eight
- Right Answers%
- Share of answers that were Right.
- Near 0.5 is expected: the sound moved each way equally often
- Median Answer Timems
- Median time from when the answers opened, after the sounds, to the answer.
- Informational; the answer has no time limit
- Anticipationscount
- Answers within 100 ms of the answers opening, which leave the staircase where it was.
- Half or more of the answers makes the session invalid
- Completed Trialstrials
- Trials answered in the scored run.
- Fewer than planned is flagged for review
- Planned Trialstrials
- Trials the run set out to play.
- Informational
- Left-Right Check Passed0/1
- 1 when every tone of a round of the left-right check was placed on its side, 0 when the second round had an error too.
- 0 stops the test unless the study set it to continue
- Left-Right Check Roundscount
- Rounds of the left-right check played: 1, or 2 after an error.
- Informational
- Headphone Check Passed0/1
- 1 when the headphone check passed (at least 5 of 6 right), 0 when it did not.
- 0 stops the test unless the study set it to continue
- Headphone Check Correctcount
- Headphone check trials answered right, of 6.
- 5 or 6 passes
- Reported Output Delayms
- Output delay the device reported to the browser; empty when the browser does not report it.
- Informational
Use and evidence
88 papers from 2021 to 2025 name this task in their title or abstract, down 16% compared with 2016 to 2020. That ranks it 296 of 670 test families in our census. See the counts for every test.
Show the numbers
| Year | Papers |
|---|---|
| 2025 | 14 |
| 2024 | 13 |
| 2023 | 21 |
| 2022 | 17 |
| 2021 | 23 |
| 2020 | 23 |
| 2019 | 15 |
| 2018 | 26 |
| 2017 | 20 |
| 2016 | 21 |
| 2015 | 15 |
| 2014 | 16 |
| 2013 | 23 |
| 2012 | 11 |
| 2011 | 13 |
| 2010 | 14 |
| 2009 | 23 |
| 2008 | 21 |
| 2007 | 17 |
| 2006 | 18 |
| 2005 | 13 |
| 2004 | 6 |
| 2003 | 11 |
| 2002 | 5 |
| 2001 | 7 |
| 2000 | 5 |
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
- 18
- Registered clinical studies using it as an outcome
- 3
Measured on ConductCognition
Pooled across the studies that feed our platform norms, by device group. A figure needs 50 or more people.
No pooled figure yet.
Note on the counts: includes animal and cochlear implant studies.
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 0.48.0, counted 12 November 2026 from OpenAlex and ClinicalTrials.gov.
Task design
The trial sequence as the test runs in ConductCognition.
- Sound setup
- The participant turns the device's volume until a steady 1 kHz tone is comfortable, then takes a 6-trial headphone check (Woods and colleagues, 2017). By default a failed check ends the test; its result is saved either way.
- Left-right check
- A 1,000 Hz tone in one ear at a time, four trials, as in the Dichotic Listening Task. An error brings a reminder to wear the earphone marked L on the left ear and a second round; by default a second error ends the test.
- Trial
- Press Play to hear two 400 ms sounds, 200 ms apart. The first carries half the difference between the ears toward one side and the second half toward the other, so the sound moves. Choose Left or Right, with no time limit.
- Sounds
- Noise from 100 to 4,000 Hz, new for every sound (standard), or a 500 Hz tone, with 100 ms raised-cosine ramps that start and end together in both ears, 10 dB below the volume-setting tone. The time difference is made in the frequency domain, exact to a fraction of a sample; the level difference is split between the ears.
- Staircases
- Two, interleaved in an order drawn from the session's seed: time from 200 µs and level from 6 dB. Two right answers in a row make the difference smaller and one error makes it larger, which keeps a listener near 71 percent right. Time moves by a factor of 10^0.2 until the fourth turnpoint and 10^0.05 after it, from 2 to 796 µs; level by 1 dB, then 0.25 dB, from 0.25 to 12 dB.
- Trials
- 60 trials on each staircase (standard, 30 to 80): 120 trials, with no feedback.
- Practice
- 4 trials at 600 µs and 10 dB, the sound moving each way once on each staircase, with feedback for 1,000 ms.
- Score
- Each threshold is the mean of the last eight turnpoints after the first four, geometric for time, as Ochi and colleagues (2014) computed theirs: the time threshold in µs and the level threshold in dB. Answers under 100 ms leave the staircase where it was.
The sounds play through the participant's own headphones at a volume they chose, and only the difference between the ears adapts: every sound plays at the same level. Each trial asks which way the sound moved, so a device's own left-right balance does not decide the answer. Answers mostly the wrong way make a session invalid, as when the earphones are worn the other way round. The test needs normal hearing and headphones, wired if possible: wireless headphones can add delay and change the sound. It is a research measure, not a hearing test: it gives no hearing level and no pass or fail, and its scores are not a sign of hearing loss. No percentile is given.
Quality checks
Each session is marked valid, needs review or invalid, with the reason, before you see its scores.
Scored rows: sound_lateralization_test from the selected run: two sounds, then Left or Right for the way the sound moved, with no time limit, graded from the saved button and the direction played. The two 2-down 1-up staircases, time and level, are replayed from the answers, and each threshold averages the last eight turnpoints after the first four. Chance is one half. Below chance invalidates and not above chance is flagged; one button on 90% of answers invalidates when accuracy is not above chance; answers under 100 ms leave the staircase where it was and invalidate when at least half. A headphone check or left-right check that stopped the test invalidates; a failed check with the test run anyway, a staircase with too few turnpoints, a threshold at half the largest difference or more, and a run short of its planned trials are flagged for review.
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). A staircase keeps a listener who hears the sounds move near 71 percent right (Levitt, 1971), so accuracy near one half means the answers did not follow the sounds, and accuracy below it that the ears were swapped. The answers open once both sounds have played, so an answer under 100 ms was pressed before they opened. Woods, Siegel, Traer and McDermott (2017) let only listeners who passed the headphone check go on, because a listener on loudspeakers hears the sounds differently; a session that ran after a failed check keeps its scores but not its percentile. The task needs each ear's sound in that ear, so a left-right check stands beside the headphone check, as in the Dichotic Listening Task.
No percentile. Scores and quality flags only.
Running this test
Settings you can change
| Setting | Standard | Allowed |
|---|---|---|
| Trials per staircase | 60 | 30 to 80 |
| Sound | Noise bursts | Noise bursts, 500 Hz tones |
| When the headphone check fails | Stop the test | Stop the test, Continue the test |
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. Needs headphones. 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 Lateralization Task in a web browser (ConductCognition task version 1.0.0, scoring version 1.0.0; Klumpp and Eady, 1956; Yost and Dye, 1988; Ochi, Yamasoba and Furukawa, 2014), with the standard settings (trials per staircase: 60; sound: Noise bursts; when the headphone check fails: Stop the test). The main score was ITD threshold (the difference in arrival time between the ears, from the first sound to the second, that the listener follows on about 71 percent of trials: the geometric mean of the last eight turnpoints after the first four).
ConductCognition versions: task version 1.0.0, scoring version 1.0.0. Every export records the versions each session used, for a methods section.
- Klumpp, R. G., & Eady, H. R. (1956). Some measurements of interaural time difference thresholds. The Journal of the Acoustical Society of America, 28(5), 859-860. https://doi.org/10.1121/1.1908493The smallest difference in arrival time between the ears that listeners can detect.
- Yost, W. A. (1974). Discriminations of interaural phase differences. The Journal of the Acoustical Society of America, 55(6), 1299-1303. https://doi.org/10.1121/1.1914701Time differences carried by tones as phase differences between the ears.
- Yost, W. A., & Dye, R. H. (1988). Discrimination of interaural differences of level as a function of frequency. The Journal of the Acoustical Society of America, 83(5), 1846-1851. https://doi.org/10.1121/1.396520The smallest level difference between the ears that listeners can detect.
- Ochi, A., Yamasoba, T., & Furukawa, S. (2014). Factors that account for inter-individual variability of lateralization performance revealed by correlations of performance among multiple psychoacoustical tasks. Frontiers in Neuroscience, 8, 27. https://doi.org/10.3389/fnins.2014.00027The method: two sounds with half the difference toward each side, the direction of the move reported, and 2-down 1-up staircases.
- Levitt, H. (1971). Transformed up-down methods in psychoacoustics. The Journal of the Acoustical Society of America, 49(2B), 467-477. https://doi.org/10.1121/1.1912375The 2-down 1-up rule, which tracks 70.7 percent right.
- Woods, K. J. P., Siegel, M. H., Traer, J., & McDermott, J. H. (2017). Headphone screening to facilitate web-based auditory experiments. Attention, Perception, & Psychophysics, 79(7), 2064-2072. https://doi.org/10.3758/s13414-017-1361-2The headphone check before the test.
Source papers
- Klumpp and Eady (1956): interaural time difference thresholds. Yost and Dye (1988): interaural level difference thresholds across frequency. Ochi, Yamasoba and Furukawa (2014): both thresholds from two sounds and a 2-down 1-up track, in 22 adults.Paradigm source, Adults
Questions
How long does the Lateralization Task take?
About 7 to 9 minutes, as listed in the test library.
What device does a participant need?
Untimed test: runs on desktops, laptops, tablets and phones. Needs headphones. The browser must be Chrome, Edge, Firefox or Safari.
What scores does it produce?
ITD Threshold, ILD Threshold, Time Staircase Accuracy, Level Staircase Accuracy, Time Staircase Turnpoints, Level Staircase Turnpoints, Right Answers, Median Answer Time, Anticipations, Completed Trials, Planned Trials, Left-Right Check Passed, Left-Right Check Rounds, Headphone Check Passed, Headphone Check Correct and Reported Output Delay. Each session is also marked valid, needs review or invalid, with the reason.
How widely is the Lateralization Task used in research?
88 papers from 2021 to 2025 name it in their title or abstract, down 16% compared with 2016 to 2020. That ranks it 296 of 670 test families in the ConductCognition test census (use grade D). Source: ConductCognition test census 0.48.0, counted 12 November 2026 from OpenAlex and ClinicalTrials.gov.
How much reliability evidence does the Lateralization 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).
Does it report a percentile?
No. Scores and quality flags only.
Which settings can a researcher change?
Trials per staircase (30 to 80), sound (Noise bursts, 500 Hz tones) and when the headphone check fails (Stop the test, Continue the test). 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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