Attention
Continuity Illusion Task
Also called: auditory continuity illusion, auditory induction, temporal induction, illusory continuity, perceptual restoration of tones, picket-fence effect
Measure how often a tone seems to go on through noise: a broken 1 kHz tone through headphones, its gap silent or filled with noise at five fixed levels.
6-9 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
- 22
- Evidence grade
- D
- Registered clinical studies
- 0
What it measures
Measures how often a tone seems to go on through a burst of noise that replaced part of it. Through headphones, participants hear a 1 kHz tone with a short break that is silent or filled with noise at five levels fixed before the session, or a tone that goes on under the noise, and say whether it stopped or went on. The main score is the share of broken tones heard as going on under noise, less the share with a silent break. A research measure, not a hearing test.
Constructs
- Auditory continuity illusion
- Perceptual restoration
- Auditory scene analysis
- Auditory masking
Research uses
- Auditory scene analysis research
- Auditory perception research
- Within-study group comparison
How the paradigm works
The auditory continuity illusion: when part of a sound is replaced by a noise that could have masked it, listeners hear the sound going on through the noise, and when the gap is left silent they hear the break (Warren, Obusek and Ackroff, 1972). The illusion grows with the noise's power near the sound's frequency (Riecke, van Opstal and Formisano, 2008), the masking that would have hidden the missing part. This task measures it with a tone and bands of noise over headphones. It needs headphones and normal hearing. The test starts with the sound setup: the participant turns the device's volume until a steady tone is comfortable, and a six-trial headphone check (Woods, Siegel, Traer and McDermott, 2017) confirms that headphones are in use. By default a failed check ends the test, and the check's result is saved either way.
More about the paradigm
On each trial the participant presses Play and hears a 1 kHz tone for 400 ms, a 200 ms interruption, and the tone again for 400 ms, its second part the same sine the tone would have had going on. The interruption is silent, or filled with a one-third-octave band of noise centered on 1 kHz whose 10 ms ramps lie over the tone's, after Kobayashi and Kashino (2012); on other trials the tone goes on under the same noise. The noise comes at five levels relative to the tone, from 9 dB below to 15 dB above it in 6 dB steps (the ratio of their rms values), and the tone is 25 dB below the volume-setting tone. The participant answers It stopped or It went on, with no time limit. Each run holds two silent gaps and, at each noise level, a broken tone and a tone going on under the noise, 12 trials in an order drawn from the session's seed: 96 trials at the standard 8 runs (5 to 12 as a setting). Six practice trials, the silent gap and the softest noise in a broken and a going-on tone, give feedback; the test gives none. The levels are set before the session and no answer changes the ones that follow, so there is no staircase. The browser makes the tone and the noise and starts each trial's sound on the audio clock's sample grid; the output delay the device reports is saved.
The main score is the continuity effect: the share of broken tones heard as going on when the noise filled the gap, over the five levels, less the share when the gap was silent. The share at each noise level comes with it, and the noise level at which half the broken tones are heard as going on, from a cumulative Gaussian fitted by maximum likelihood. Tones that truly go on under the noise should be heard as going on at every level, so a session where they mostly are not is flagged. Studies of how the brain restores interrupted tones use the same kind of judgment in healthy and clinical groups (Wooldridge and colleagues, 2020).
Scores
- Continuity Effect%
- Share of broken tones heard as going on with noise in the gap, over the five levels, less the share with a silent gap.
- Higher means a stronger illusion; not a hearing level
- Continuity Under Noise%
- Share of broken tones heard as going on when the noise filled the gap, over the five levels.
- Higher means the noise more often filled the gap
- Continuity in Silence%
- Share of broken tones heard as going on when the gap was silent.
- Near 0 is expected
- Continuity by Noise Level%
- Share of broken tones heard as going on at each noise level, keyed by the noise's level re the tone in dB.
- Rises with the noise's level
- Continuity ThresholddB
- The noise's level re the tone, in dB, at which the fitted curve gives half the broken tones heard as going on.
- Lower means a softer noise filled the gap; not a hearing level
- True Continuity%
- Share of tones that went on under the noise heard as going on.
- Near 1 is expected; under 0.5 is flagged
- Median Answer Timems
- Median time from when the answers opened, after the sound, to the answer.
- Informational; the answer has no time limit
- Anticipationscount
- Answers within 100 ms of the answers opening, which leave the score.
- 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
- 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
22 papers from 2021 to 2025 name this task in their title or abstract. That ranks it 393 of 495 test families in our census. See the counts for every test.
Show the numbers
| Year | Papers |
|---|---|
| 2025 | 15 |
| 2024 | 4 |
| 2023 | 2 |
| 2022 | 0 |
| 2021 | 1 |
| 2020 | 2 |
| 2019 | 0 |
| 2018 | 2 |
| 2017 | 0 |
| 2016 | 3 |
| 2015 | 3 |
| 2014 | 1 |
| 2013 | 4 |
| 2012 | 6 |
| 2011 | 5 |
| 2010 | 6 |
| 2009 | 5 |
| 2008 | 8 |
| 2007 | 6 |
| 2006 | 1 |
| 2005 | 3 |
| 2004 | 3 |
| 2003 | 3 |
| 2002 | 2 |
| 2001 | 0 |
| 2000 | 1 |
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.
- 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.
- Trial
- Press Play to hear a 1 kHz tone for 400 ms, a 200 ms interruption and the tone again for 400 ms. Choose It stopped or It went on, with no time limit.
- Interruptions
- Silent; filled with a one-third-octave band of noise at 1 kHz whose 10 ms ramps lie over the tone's, after Kobayashi and Kashino (2012); or the tone going on under the same noise.
- Levels
- Five noise levels relative to the tone: -9, -3, 3, 9 and 15 dB, as the ratio of the noise's rms to the tone's. The tone is 25 dB below the volume-setting tone, so the noise runs from 34 to 10 dB below it.
- Trials
- Each run holds two silent gaps and, at each level, a broken tone and a tone going on under the noise, 12 trials in an order drawn from the session's seed. 8 runs (standard, 5 to 12): 96 trials, with no feedback.
- Practice
- 6 trials, the silent gap and the softest noise in a broken and a going-on tone, with feedback for 1,000 ms.
- Fixed levels
- Every level is set before the session, and no answer changes the next one: there is no staircase. The browser makes the tone and the noise and starts each sound on the audio clock's sample grid; the output delay the device reports is saved.
- Score
- The continuity effect: the share of broken tones heard as going on with noise in the gap, less the share with a silent gap. The noise level at which half the broken tones are heard as going on comes from a cumulative Gaussian fitted by maximum likelihood. Answers under 100 ms leave the score.
Levels are relative to the tone and to the volume the participant chose, not sound pressure levels, and headphones differ, so compare results within studies run the same way. Tones that go on under the noise but are mostly answered as stopped flag a session. 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: continuity_illusion_test from the scored run, a button for It stopped or It went on after the sound has played, with no time limit. An interrupted tone with noise in the gap has no correct answer, so only two kinds of trial are judged: a silent gap (it stopped) and a tone going on under the softest noise (it went on), one right button of two. Those below chance invalidate and not above chance are flagged; one button on 90% of answers invalidates when they are not above chance; answers under 100 ms invalidate when they are at least half. Tones going on under the noise answered as going on less than half the time, no continuity threshold within the levels played, a failed headphone check with the test run anyway, or a run short of its planned trials is flagged for review; a headphone check that stopped the test invalidates.
Why these rules
Whether an interrupted tone is heard going on through the noise is what the test measures, so it has no correct answer. A silent gap is heard as a break, and a tone 9 dB above a soft noise is heard going on, so answers below chance on those trials mean the buttons were swapped or the task was not followed. 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). The answers open once the sound has played and have no time limit, so an answer under 100 ms was pressed before they opened, and only a session made mostly of such answers is invalid. A threshold outside the levels played cannot be estimated from them. 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.
No percentile. Scores and quality flags only.
Running this test
Settings you can change
| Setting | Standard | Allowed |
|---|---|---|
| When the headphone check fails | Stop the test | Stop the test, Continue the test |
| Runs | 8 | 5 to 12 |
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 Continuity Illusion Task in a web browser (ConductCognition task version 1.0.0, scoring version 1.0.0; Warren, Obusek and Ackroff, 1972; Riecke, van Opstal and Formisano, 2008), with the standard settings (when the headphone check fails: Stop the test; runs: 8). The main score was continuity effect (share of broken tones heard as going on with noise in the gap, over the five levels, less the share with a silent gap).
ConductCognition versions: task version 1.0.0, scoring version 1.0.0. Every export records the versions each session used, for a methods section.
- Warren, R. M., Obusek, C. J., & Ackroff, J. M. (1972). Auditory induction: Perceptual synthesis of absent sounds. Science, 176(4039), 1149-1151. https://doi.org/10.1126/science.176.4039.1149A fainter sound replaced by a louder one is heard going on through it.
- Riecke, L., van Opstal, A. J., & Formisano, E. (2008). The auditory continuity illusion: A parametric investigation and filter model. Perception & Psychophysics, 70(1), 1-12. https://doi.org/10.3758/PP.70.1.1Perceived continuity of interrupted and uninterrupted tones as the power of the interrupting noise changes.
- Kobayashi, M., & Kashino, M. (2012). Effect of flanking sounds on the auditory continuity illusion. PLoS ONE, 7(12), e51969. https://doi.org/10.1371/journal.pone.0051969The sounds: a 1 kHz tone and a one-third-octave band of noise at 1 kHz with overlapping 10 ms ramps.
- Wooldridge, J., Kaiser, M., Roa Romero, Y., Riecke, L., Keil, J., & Senkowski, D. (2020). Low-frequency oscillations reflect aberrant tone restoration during the auditory continuity illusion in schizophrenia. Scientific Reports, 10, 11872. https://doi.org/10.1038/s41598-020-68414-3Interrupted and continuous tones under noise, judged continuous or interrupted.
- 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
- Warren, Obusek and Ackroff (1972): a fainter sound heard through a louder one that replaced it. Riecke, van Opstal and Formisano (2008): perceived continuity of interrupted and uninterrupted tones as a function of the noise's power.Paradigm source, Adults
Questions
How long does the Continuity Illusion Task take?
About 6 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?
Continuity Effect, Continuity Under Noise, Continuity in Silence, Continuity by Noise Level, Continuity Threshold, True Continuity, Median Answer Time, Anticipations, Completed Trials, Planned Trials, 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 Continuity Illusion Task used in research?
22 papers from 2021 to 2025 name it in their title or abstract. That ranks it 393 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 Continuity Illusion 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?
When the headphone check fails (Stop the test, Continue the test) and runs (5 to 12). 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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