Attention
Biological Motion Task
Also called: point-light walker task, biological motion perception, point-light display, walker direction discrimination
Measure how much noise a person tolerates when judging which way a point-light walker faces, with a staircase on the number of mask dots.
4-6 minTimed: desktop or laptop with a mouse or trackpad
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- Papers, 2021 to 2025
- 624
- Evidence grade
- C
- Registered clinical studies
- 28
What it measures
Measures how well a person sees a walking figure made of dots among moving noise dots. The walker faces left or right and participants press an arrow key for its direction. A staircase on the number of noise dots finds how much noise the person tolerates at about 71% correct.
Constructs
- Biological motion perception
- Global motion integration
- Social perception
Research uses
- Perception and social cognition research
- Within-study group comparison
- Individual differences in biological motion sensitivity
How the paradigm works
The biological motion task measures how well a person sees a walking human figure in a few moving dots. Thirteen white dots mark the head, shoulders, elbows, wrists, hips, knees and ankles of a figure that walks in place for one gait cycle, facing left or right. Johansson (1973) showed that such point-light displays give a vivid impression of a walking person, although each dot alone moves without meaning. Participants press the left or right arrow key for the direction the walker faces.
More about the paradigm
The walker is hidden among mask dots that copy the motions of the walker's own dots at scrambled places, so no single dot tells the direction and only the figure as a whole does (Bertenthal and Pinto, 1994). A 2-down 1-up staircase on the number of mask dots (Levitt, 1971) finds the mask the participant tolerates at about 71% correct, as in the noise thresholds of Neri, Morrone and Burr (1998). Trials with the walker alone check that the participant can see it. An upside-down block, with its own staircase, can be added: the walker is much harder to see upside down, which Bertenthal and Pinto (1994) took as evidence for processing of the whole figure.
The walker comes from ConductScience's own gait model: smooth periodic joint angles, each arm swinging against the leg on its side, a vertical bounce twice per cycle and a gait cycle of one second, redrawn on every screen frame at the measured refresh rate.
Scores
- Noise Thresholdcount
- Mask dots tolerated at about 71% correct in the upright block: the geometric mean of the mask sizes at the last six staircase reversals, after the first two.
- Higher means the walker was seen in more noise
- Staircase Reversalscount
- Times the upright staircase changed direction.
- Six or more are needed for a threshold
- Catch Accuracy%
- Share correct on the upright trials with the walker alone and no mask dots.
- Below 0.75 is flagged for review
- Catch Trials Answeredcount
- Upright trials with no mask dots answered at or after 100 ms.
- Informational
- Accuracy%
- Share correct on the upright staircase trials.
- The staircase holds it near 0.71
- Median Correct RTms
- Median response time of correct answers on the upright staircase trials, from the walker's onset.
- Lower is faster
- Accuracy by Mask Size%
- Share correct at each number of mask dots shown in the upright block, keyed by the number of dots.
- Falls as the mask grows
- Upside-down Noise Thresholdcount
- Noise threshold in the upside-down block, when it runs.
- Higher means the walker was seen in more noise
- Upside-down Staircase Reversalscount
- Times the upside-down staircase changed direction.
- Six or more are needed for a threshold
- Upside-down Catch Accuracy%
- Share correct on the upside-down trials with no mask dots.
- Higher is better
- Upside-down Accuracy%
- Share correct on the upside-down staircase trials.
- The staircase holds it near 0.71
- Upside-down Median Correct RTms
- Median response time of correct answers on the upside-down staircase trials.
- Lower is faster
- Inversion Effectcount
- Upright noise threshold minus the upside-down noise threshold.
- Positive means the upright walker was seen in more noise
- Dropped Frame Rate%
- Share of display frames the browser dropped while the walker moved.
- Above 0.05 is flagged for review
Use and evidence
624 papers from 2021 to 2025 name this task in their title or abstract, down 2% compared with 2016 to 2020. That ranks it 37 of 395 test families in our census. See the counts for every test.
Show the numbers
| Year | Papers |
|---|---|
| 2025 | 141 |
| 2024 | 160 |
| 2023 | 126 |
| 2022 | 111 |
| 2021 | 86 |
| 2020 | 107 |
| 2019 | 98 |
| 2018 | 133 |
| 2017 | 142 |
| 2016 | 154 |
| 2015 | 146 |
| 2014 | 138 |
| 2013 | 162 |
| 2012 | 163 |
| 2011 | 149 |
| 2010 | 239 |
| 2009 | 108 |
| 2008 | 77 |
| 2007 | 69 |
| 2006 | 72 |
| 2005 | 78 |
| 2004 | 63 |
| 2003 | 49 |
| 2002 | 45 |
| 2001 | 38 |
| 2000 | 28 |
Use grade B
300 to 999 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
- 5
- Papers on reliability or validity
- 104
- Registered clinical studies using it as an outcome
- 28
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.
- Walker
- 13 white dots on black for the head, shoulders, elbows, wrists, hips, knees and ankles of a figure 220 pixels tall, walking in place.
- Gait
- One gait cycle of 1,000 ms per trial, from a random starting phase, facing left or right.
- Mask
- Dots that copy the walker's own dot motions at random places in a 300 by 300 pixel area, half from a walker facing left and half from one facing right.
- Staircase
- 2-down 1-up on the number of mask dots, from 16 dots, in steps of a third of a doubling (4 to 512 dots), aiming at 71% correct.
- Catch trials
- One trial with the walker alone for every 9 staircase trials.
- Fixation
- 500 ms.
- Answer
- From the walker's onset until 3,000 ms after it ends.
- Keys
- Left and right arrows for the direction the walker faces.
- Length
- 72 staircase trials per block (40 to 120), with a break after every 40.
- Practice
- 8 trials with feedback and the walker alone, and 4 more upside down before an upside-down block.
- Upside-down block
- Optional, with its own staircase, in a random order with the upright block.
- Timing
- The walker is redrawn on every screen frame at the measured refresh rate; more than 5% dropped frames is flagged for review.
Bertenthal and Pinto (1994) showed an 11-dot walker among a fixed mask of 66 dots, with a gait cycle of 2 seconds and displays of 1 or 2 seconds. This version uses ConductScience's own 13-dot gait model with a 1 second gait cycle and finds the mask each participant tolerates with a staircase, as in noise-threshold studies such as Neri, Morrone and Burr (1998).
Quality checks
Each session is marked valid, needs review or invalid, with the reason, before you see its scores.
Scored rows: biological_motion_test from the scored run, left or right arrow for the direction the walker faces (chance 50%, each direction on half the trials) from the walker's onset until 3,000 ms after the walk ends. Below chance invalidates and not above chance is flagged. One key on 90% of answers invalidates when accuracy is not above chance. Missed responses and responses under 100 ms follow the timed-test rule. More than 5% of display frames dropped, an upright staircase with too few reversals for a threshold, or under 75% correct on at least four answered upright trials with no mask dots is 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). 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. The threshold depends on a walker that moves on every screen frame, so a display that drops frames changes the motion. The trials with no mask dots are easy for anyone who can see the walker, so errors on them mean the display or the task was not followed.
Running this test
Settings you can change
| Setting | Standard | Allowed |
|---|---|---|
| Staircase trials per block | 72 | 40 to 120 |
| Add an upside-down block | Off | On or off |
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 Biological Motion Task in a web browser (ConductCognition task version 1.0.0, scoring version 1.0.0; Johansson, 1973; Bertenthal and Pinto, 1994), with the standard settings (staircase trials per block: 72; add an upside-down block: Off). The main score was noise threshold (mask dots tolerated at about 71% correct in the upright block: the geometric mean of the mask sizes at the last six staircase reversals, after the first two).
ConductCognition versions: task version 1.0.0, scoring version 1.0.0. Every export records the versions each session used, for a methods section.
- Johansson, G. (1973). Visual perception of biological motion and a model for its analysis. Perception & Psychophysics, 14(2), 201-211. https://doi.org/10.3758/BF03212378
- Bertenthal, B. I., & Pinto, J. (1994). Global processing of biological motions. Psychological Science, 5(4), 221-225. https://doi.org/10.1111/j.1467-9280.1994.tb00504.xMasked direction judgment, scrambled-walker mask and the inversion effect.
- Neri, P., Morrone, M. C., & Burr, D. C. (1998). Seeing biological motion. Nature, 395(6705), 894-896. https://doi.org/10.1038/27661Noise thresholds for point-light walkers.
- Levitt, H. (1971). Transformed up-down methods in psychoacoustics. The Journal of the Acoustical Society of America, 49(2B), 467-477. https://doi.org/10.1121/1.19123752-down 1-up staircase, which converges on 70.7% correct.
Source papers
- Johansson G (1973). Visual perception of biological motion and a model for its analysis. Perception & Psychophysics, 14(2):201-211.Paradigm source, Adults
- Bertenthal BI, Pinto J (1994). Global processing of biological motions. Psychological Science, 5(4):221-225.Paradigm source, Adults
- Neri P, Morrone MC, Burr DC (1998). Seeing biological motion. Nature, 395(6705):894-896.Paradigm source, Adults
- Levitt H (1971). Transformed up-down methods in psychoacoustics. Journal of the Acoustical Society of America, 49(2B):467-477.Paradigm source
Questions
How long does the Biological Motion 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?
Noise Threshold, Staircase Reversals, Catch Accuracy, Catch Trials Answered, Accuracy, Median Correct RT, Accuracy by Mask Size, Upside-down Noise Threshold, Upside-down Staircase Reversals, Upside-down Catch Accuracy, Upside-down Accuracy, Upside-down Median Correct RT, Inversion Effect and Dropped Frame Rate. Each session is also marked valid, needs review or invalid, with the reason.
How widely is the Biological Motion Task used in research?
624 papers from 2021 to 2025 name it in their title or abstract, down 2% compared with 2016 to 2020. That ranks it 37 of 395 test families in the ConductCognition test census (use grade B). Source: ConductCognition test census 0.14.0, counted 31 October 2026 from OpenAlex and ClinicalTrials.gov.
How much reliability evidence does the Biological Motion Task have?
In the published research, 5 papers report its test-retest reliability and 28 registered clinical studies use it as an outcome (evidence grade C in the ConductCognition test census).
Which settings can a researcher change?
Staircase trials per block (40 to 120) and add an upside-down block (On or off). 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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