Working Memory
Symmetry Span Task
Also called: SSPAN, SymSpan, automated symmetry span, complex span task, spatial span with symmetry judgments
Measure spatial complex working memory with patterns judged for symmetry while the places of red squares are held in mind and recalled in order.
8-12 minUntimed
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
- 30
- Evidence grade
- C
- Registered clinical studies
- 13
What it measures
Measures working memory capacity with the automated symmetry span procedure. Participants judge whether patterns are symmetrical while remembering where red squares appeared, then recall the places in order.
Constructs
- Working memory capacity
- Executive attention
- Spatial short-term memory
- Serial recall of locations
Research uses
- Individual-difference studies of working memory capacity
- Spatial ability and reasoning research
- Cognitive training and intervention outcome studies
How the paradigm works
The symmetry span task measures complex working memory: keeping places in mind while judging patterns. On each item the participant looks at a pattern of black squares in an 8 by 8 grid, clicks Continue, and then answers whether the pattern is symmetrical about its vertical axis. A red square follows in one cell of a 4 by 4 grid. After each set, the participant clicks the places in the order shown on an empty 4 by 4 grid, using a Blank button for any place they forgot.
More about the paradigm
The task follows the automated symmetry span (Unsworth et al. 2009; Redick et al. 2012), which Kane and colleagues (2004) introduced. Practice has three parts: places only, 15 patterns only, and both together. The pattern practice sets each participant's time limit for later patterns at their mean time plus 2.5 standard deviations. The test has 12 sets, three each of 2 to 5 places in random order, for 42 patterns and places; a setting gives one or two sets of each size instead. Each red square shows for 650 ms, adjustable from 500 to 1,000 ms. A pattern that runs past the time limit counts as a speed error and the task moves on to the red square.
The patterns are drawn by code for each session. A symmetrical pattern fills 16 random squares of the left half and mirrors them into the right half. A pattern that is not symmetrical changes 4 squares of such a pattern, each in a different mirrored pair, and keeps the same number of black squares. Half the patterns are symmetrical, and the places in a set are all different.
The main score is the partial span score: places recalled in the correct position, 0 to 42. The absolute span score, symmetry accuracy, speed and accuracy errors, and recall at each set size are also reported. Sessions with symmetry accuracy below 85% are flagged. Scores support research and do not diagnose.
Scores
- Partial Span Scorecount
- Places recalled in the correct position across all sets (0 to 42 at the standard settings).
- Higher is better
- Absolute Span Scorecount
- Sum of set sizes for sets recalled perfectly.
- Higher is better
- Partial-Credit Unit Score%
- Mean proportion of places recalled in the correct position per set.
- Higher is better
- Symmetry Accuracy%
- Patterns judged correctly within the time limit, out of all patterns shown.
- Below 0.85 flags the session
- Symmetry Errorscount
- Speed errors plus accuracy errors.
- Lower is better
- Speed Errorscount
- Patterns not judged within the participant's time limit.
- Lower is better
- Accuracy Errorscount
- Patterns judged wrongly as symmetrical or not.
- Lower is better
- Low Symmetry Accuracyflag
- 1 when symmetry accuracy is below 85%; review before analysis.
- Informational
- Recall, Sets of 2%
- Proportion of places recalled in the correct position in sets of 2.
- Higher is better
- Recall, Sets of 3%
- Proportion of places recalled in the correct position in sets of 3.
- Higher is better
- Recall, Sets of 4%
- Proportion of places recalled in the correct position in sets of 4.
- Higher is better
- Recall, Sets of 5%
- Proportion of places recalled in the correct position in sets of 5.
- Higher is better
- Median Pattern Timems
- Median time from a pattern's appearance to Continue, for patterns judged within the time limit.
- Context for the time limit
- Pattern Time Limitms
- The participant's time limit per pattern: mean practice time plus 2.5 SD.
- Informational
Use and evidence
30 papers from 2021 to 2025 name this task in their title or abstract, down 35% compared with 2016 to 2020. That ranks it 303 of 395 test families in our census. See the counts for every test.
Show the numbers
| Year | Papers |
|---|---|
| 2025 | 5 |
| 2024 | 7 |
| 2023 | 4 |
| 2022 | 10 |
| 2021 | 4 |
| 2020 | 7 |
| 2019 | 6 |
| 2018 | 17 |
| 2017 | 14 |
| 2016 | 2 |
| 2015 | 4 |
| 2014 | 2 |
| 2013 | 1 |
| 2012 | 1 |
| 2011 | 0 |
| 2010 | 1 |
| 2009 | 0 |
| 2008 | 1 |
| 2007 | 0 |
| 2006 | 0 |
| 2005 | 0 |
| 2004 | 0 |
| 2003 | 0 |
| 2002 | 0 |
| 2001 | 0 |
| 2000 | 0 |
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
- 11
- Registered clinical studies using it as an outcome
- 13
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.
- Places
- A red square in one cell of a 4 by 4 matrix, shown for 650 ms (standard; 500 to 1,000).
- Sets
- 12 sets, three each of 2 to 5 places in random order: 42 places and 42 patterns (standard; one to three sets of each size).
- Patterns
- 8 by 8 grids drawn by code for each session. A symmetrical pattern mirrors 16 black squares of the left half into the right half; one that is not symmetrical changes 4 squares, each in a different mirrored pair, and keeps 32 black squares. Half the patterns shown are symmetrical.
- Judgment
- After looking, the participant clicks Continue, then Symmetrical or Not symmetrical.
- Time limit
- Each participant's mean time in pattern practice plus 2.5 standard deviations. A pattern not judged in time is a speed error.
- Recall
- Click the places in order on an empty 4 by 4 matrix, with a Blank button for a forgotten place, then 2,000 ms of feedback.
- Practice
- Places only (sets of 2, 2, 3 and 3), 15 patterns only with feedback, then three sets of 2 with both.
- Symmetry criterion
- Sessions below 85% symmetry accuracy are flagged.
The automated symmetry span uses its own pattern set. These patterns are drawn by code for each session, so published symmetry span norms are not applied.
Quality checks
Each session is marked valid, needs review or invalid, with the reason, before you see its scores.
Scored rows: test-phase answers to whether each pattern is symmetrical (chance 50%, half are) and speed errors, in the order shown, from the scored run. Symmetry accuracy below chance invalidates and not above chance is flagged. One button on 90% of answers invalidates when accuracy is not above chance. Speed errors are missed responses: more than max(3, 25%) invalidate, any is flagged. Answers under 200 ms on at least half the patterns invalidate. Symmetry accuracy below 85% is flagged. Place recall is not judged against chance. A hidden tab withholds the percentile.
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). Typical participants make less than one speed error on the automated symmetry span (Redick et al. 2012, M 0.67), so more than a quarter signals non-engagement. Unsworth et al. (2005; 2009) and Redick et al. (2012) kept participants whose processing accuracy reached 85%, so accuracy below that is flagged. An answer under 200 ms is faster than a simple visual reaction, so it cannot reflect the item. Following response-time effort screening for untimed tests (Wise and Kong 2005), the session is invalid only when at least half the answers are that fast. A hidden tab lets the study, delay or response timers run without the participant, so a percentile is withheld after one.
Running this test
Settings you can change
| Setting | Standard | Allowed |
|---|---|---|
| Sets of each size | 3 | 1 to 3 |
| Red square display time (ms) | 650 | 500 to 1,000 |
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. 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 Symmetry Span Task in a web browser (ConductCognition task version 1.0.0, scoring version 1.0.0; Kane et al., 2004), with the standard settings (sets of each size: 3; red square display time (ms): 650). The main score was partial span score (places recalled in the correct position across all sets (0 to 42 at the standard settings)).
ConductCognition versions: task version 1.0.0, scoring version 1.0.0. Every export records the versions each session used, for a methods section.
- Kane, M. J., Hambrick, D. Z., Tuholski, S. W., Wilhelm, O., Payne, T. W., & Engle, R. W. (2004). The generality of working memory capacity: A latent-variable approach to verbal and visuospatial memory span and reasoning. Journal of Experimental Psychology: General, 133(2), 189-217. https://doi.org/10.1037/0096-3445.133.2.189
- Unsworth, N., Redick, T. S., Heitz, R. P., Broadway, J. M., & Engle, R. W. (2009). Complex working memory span tasks and higher-order cognition: A latent-variable analysis of the relationship between processing and storage. Memory, 17(6), 635-654. https://doi.org/10.1080/09658210902998047The automated symmetry span: pattern and matrix sizes, the 650 ms red square and the set sizes.
- Unsworth, N., Heitz, R. P., Schrock, J. C., & Engle, R. W. (2005). An automated version of the operation span task. Behavior Research Methods, 37(3), 498-505. https://doi.org/10.3758/BF03192720The automated procedure: practice parts, the time limit and the 85% criterion.
- Redick, T. S., Broadway, J. M., Meier, M. E., Kuriakose, P. S., Unsworth, N., Kane, M. J., & Engle, R. W. (2012). Measuring working memory capacity with automated complex span tasks. European Journal of Psychological Assessment, 28(3), 164-171. https://doi.org/10.1027/1015-5759/a000123Reliability and descriptive statistics of the automated symmetry span.
Source papers
- Kane MJ, Hambrick DZ, Tuholski SW, Wilhelm O, Payne TW, Engle RW (2004). The generality of working memory capacity: a latent-variable approach to verbal and visuospatial memory span and reasoning. Journal of Experimental Psychology: General, 133(2):189-217.Paradigm source, Young adults
- Unsworth N, Redick TS, Heitz RP, Broadway JM, Engle RW (2009). Complex working memory span tasks and higher-order cognition: a latent-variable analysis of the relationship between processing and storage. Memory, 17(6):635-654.Paradigm source, 18-35
- Unsworth N, Heitz RP, Schrock JC, Engle RW (2005). An automated version of the operation span task. Behavior Research Methods, 37(3):498-505.Paradigm source, 18-35
- Redick TS, Broadway JM, Meier ME, Kuriakose PS, Unsworth N, Kane MJ, Engle RW (2012). Measuring working memory capacity with automated complex span tasks. European Journal of Psychological Assessment, 28(3):164-171.Paradigm source, 17-35
Questions
How long does the Symmetry Span Task take?
About 8 to 12 minutes, as listed in the test library.
What device does a participant need?
Untimed test: runs on desktops, laptops, tablets and phones. The browser must be Chrome, Edge, Firefox or Safari.
What scores does it produce?
Partial Span Score, Absolute Span Score, Partial-Credit Unit Score, Symmetry Accuracy, Symmetry Errors, Speed Errors, Accuracy Errors, Low Symmetry Accuracy, Recall, Sets of 2, Recall, Sets of 3, Recall, Sets of 4, Recall, Sets of 5, Median Pattern Time and Pattern Time Limit. Each session is also marked valid, needs review or invalid, with the reason.
How widely is the Symmetry Span Task used in research?
30 papers from 2021 to 2025 name it in their title or abstract, down 35% compared with 2016 to 2020. That ranks it 303 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 Symmetry Span Task have?
In the published research, 1 paper reports its test-retest reliability and 13 registered clinical studies use it as an outcome (evidence grade C in the ConductCognition test census).
Which settings can a researcher change?
Sets of each size (1 to 3) and red square display time (ms) (500 to 1,000). 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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