SoundaryVisual Working Memory Test — Free Change Detection Task with Capacity K
A free visual working memory test in the change detection format: 4, 6 or 8 colored squares flash for half a second, then one square returns and you judge whether its color changed. Six practice and 60 test trials in about 3–5 minutes estimate how many objects you can hold at once (capacity K). A self-check, not a diagnosis.
What's included
- Time
- ~3 min
- Price
- Free
What it measures
This test measures visual working memory capacity: how many items from a glimpsed scene you can hold in mind at once. While you look at a central cross, 4, 6 or 8 colored squares appear for half a second and vanish. After a 0.9-second blank, a single square comes back, and you decide whether its color is the same as before or different.
The procedure follows the change detection paradigm introduced by Luck and Vogel in 1997, the standard way cognitive psychology estimates visual working memory capacity. By increasing the number of items and watching where accuracy breaks down, the test reveals how many objects you can hold reliably before you start losing them. This capacity underpins everyday tasks such as switching between windows or comparing locations on a map.
How to read your score
After 6 practice trials there are 60 test trials, 20 for each set size of 4, 6 and 8 (10 change and 10 same). The headline score is overall accuracy in percent, followed by accuracy per set size and your memory capacity K. K uses Cowan's formula, K = set size × (hit rate − false-alarm rate), and the largest K across the three set sizes is reported as your capacity.
K of 4 or more is labeled above average, 3 or more typical, 2 or more somewhat low and below 2 low. Adult capacity is generally around 3–4 objects. If K at 8 items is no more than 0.5 below K at 4 items, your capacity held steady up to its limit; a larger drop suggests memory scatters when more items are present.
What affects the result and how to use it
Because the test relies on brief exposures, screen size, brightness and color rendering can all affect the result. Night mode or a blue-light filter in particular can make similar colors harder to tell apart, so use the same device and settings when tracking trends. Sleep loss, too much caffeine, noise and multitasking tend to increase false alarms, especially in the 8-item condition.
Visual working memory capacity is known to be relatively stable and does not grow much with practice, which makes it well suited to tracking changes in your condition with repeat measurements a few weeks apart. If K stays below 2 across sessions on days when you feel fine, or a clear drop from your usual level lasts for weeks alongside attention or memory difficulties in daily life, consider a professional evaluation.
FAQ
What is capacity K, and what counts as normal?
K estimates how many objects you can hold in mind at once. It is computed as set size × (hit rate − false-alarm rate), and the largest value across the 4-, 6- and 8-item conditions is reported. Adults average about 3–4 objects; this test labels 4 or more as above average, 3 or more as typical, 2 or more as somewhat low and below 2 as low.
The squares disappear very quickly. Is that intended?
Yes, that is by design. The squares are shown for only half a second, and after a 0.9-second blank just one returns. Denying you time to count or name the colors is what isolates pure visual working memory, the kind that grabs a scene at a glance. The Same/Different response itself is untimed, so you can answer at your own pace.
Is accuracy around 50% the same as guessing?
Since half the trials change and half stay the same, random guessing lands near 50%, which is why K is more informative than raw accuracy. Doing well with 4 items and dropping toward 50% with 8 is a natural pattern; if you are near 50% even with 4 items, check your concentration that day and your screen setup first. The test runs 6 practice trials followed by 60 test trials.
How often should I take it, and what if my result is low?
Capacity K does not improve much with practice, so daily repeats are unnecessary; measuring every few weeks and watching the trend is enough. A single low result is easily explained by fatigue or your device setup. If K repeatedly stays below 2 on days when you feel well and you notice attention or memory difficulties in daily life, consider a professional evaluation.
Source
This task is based on the paradigm from: Luck, S. J., & Vogel, E. K. (1997). The capacity of visual working memory for features and conjunctions. Nature, 390(6657), 279–281. This task is a Soundary implementation based on a published academic paradigm. It is not any commercial test product or its test form.
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This is a self-screening tool, not a medical diagnosis. If the result concerns you, please consult a mental health professional.