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Visual attention

Conjunction Visual Search

A grid of items appears. One is the target (e.g., a green circle among red circles and green squares). Find it as fast as you can. Half the trials are "feature search" (target pops out), half are "conjunction search" (target requires serial attention).

What makes this one different

We sample set sizes 8, 16, 24 and fit your RT × set-size slope. Feature search should give a near-flat slope (target pops out). Conjunction search gives a steeper slope. The two slopes compared is the cleanest measure of attentional capacity.

Trial 0 / 24
Mean RT —
Search —

Press 1 if target present, 0 if absent. Or click the buttons.

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Your search slopes

RT slope across set size 8, 16, 24. Feature search should be near-flat; conjunction search is steeper.

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What problem does it solve?

The classic Treisman feature-integration theory predicts that searching for a unique feature (e.g., a red item among green items) is essentially parallel and "pops out," while searching for a conjunction of features (e.g., a red X among red O's and blue X's) requires serial attention. We let you see that difference in your own data.

Who is this for

How to interpret your results

Feature-search slope near 0 ms/item is expected. Anything above ~5 ms/item suggests you're not finding the pop-out.

Conjunction-search slope of 15–30 ms/item is typical. Above 40 ms/item suggests serial search is slow.

Limitations

  • Color rendering varies by display. We use high-contrast colors but calibration matters.
  • Shape complexity is limited to circles/squares/triangles for browser-render speed.
  • This is a simplified version of Treistman's lab paradigm, which uses more stimulus dimensions.

FAQ

Why are some trials missing a target?

Catch trials. If you just say "yes" to every grid, your accuracy is meaningless. About 1 in 6 trials has no target.

What if the slope is the same for both types?

Either the feature/conjunction distinction wasn't strong enough for you, or you're searching serially even when you don't need to. Both are real patterns.

How do I use Conjunction Visual Search step by step without mistakes?Follow the order given in the usage section: Find a target among distractors. We vary the search type (feature vs. conjunction) and set size, then fit your personal search slope — how RT scales with the number of items. The step-by-step part matters less than the unit check that sits inside it. Confirm every unit matches the thing you are actually trying to measure before you press calculate - that single check catches more wrong answers than any other habit, and it costs about ten seconds.
What are the common mistakes when using Conjunction Visual Search?Most common mistakes come down to four habits: entering 20 when the field expects 0.2 because the field is a percentage; leaving a field blank and accepting the default without checking what it stands for; changing one input and reading a result that was calculated before the change; and quoting the output as an exact figure when the page describes it as a reference estimate. Press calculate again after any edit, and treat the number as a reference point rather than a final answer.
How do I read the result from Conjunction Visual Search?Read the final figure first, then come back to this section for the conditions behind it: Feature-search slope near 0 ms/item is expected. Anything above ~5 ms/item suggests you're not finding the pop-out. Conjunction-search slope of 15–30 ms/item is typical. Above 40 ms/item suggests serial search is slow. Keep two things apart: the number itself, which comes from the values you typed, and the assumptions it depends on, which decide whether that number is meaningful. The page sets out what a higher or lower result means for your case, so check that direction as well as the magnitude.
Can I act on the Conjunction Visual Search result directly?Treat it as one reference sheet before you decide, rather than as the answer itself: Color rendering varies by display. We use high-contrast colors but calibration matters. Shape complexity is limited to circles/squares/triangles for browser-render speed. This is a simplified version of Treistman's lab paradigm, which uses more stimulus dimens The output describes a magnitude under the conditions you entered. It does not include what it actually costs to act, what might change while you act, or how the other side behaves. Before you commit, compare the result against reality and note which assumptions do not hold where you are.