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Visual attention

Flicker Change-Blindness Test

Two scenes alternate with a gray blank between them. Spot the change. It's harder than it sounds — without a continuous visual reference, your brain may literally not notice that an object moved, changed color, or disappeared.

What makes this one different

We include a "scene degradation" mode where parts of the scene are obscured with noise during each blank, making the change harder to spot. That exposes how much of your change-detection is actually attention versus peripheral vision.

Trial 0 / 10
Mean RT —
Miss rate —
Press Space as soon as you spot a change.
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Results

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What problem does it solve?

Change blindness is one of the most counterintuitive findings in cognitive psychology. Despite the rich visual detail around us, our visual system encodes surprisingly little of it. When a continuous reference is removed (a blink, a saccade, a flicker), large changes can go entirely unnoticed.

The phenomenon has practical implications: distracted driving, witness reliability, even UI design. Training attention is one way to reduce change blindness — and this task simulates the experience directly.

Who is this for

How to interpret your results

Miss rate of 30–50% on clean mode is normal — change blindness is real. Below 20% means you're unusually attentive or using a strategy (e.g., fixating on the change region).

Mean RT under 2 seconds is fast. Over 4 seconds is slow.

Limitations

  • The classic Rensink & O'Regan demonstrations used real photographs; we use abstract colored grids. The principle is the same but the absolute difficulty differs.
  • Display refresh rate affects flicker timing. Most users will see 60 Hz; high-refresh monitors may make it slightly easier.
  • Your eyes naturally make saccades every ~250 ms. The flicker simulates what happens at each saccade boundary.

FAQ

What does the noise mode do?

During each gray blank, random noise covers parts of the scene. This adds a "where was that?" cost — you have to remember the layout from before the noise. Most people miss more changes in noise mode.

Should I stare at the center?

Yes. Peripheral attention is what change blindness mostly defeats. Looking at the change region "cheats" the task — try to detect changes without moving your eyes.