What is change blindness, and how fast can you spot a change?
Change blindness is how easily we miss a change when a brief blink hides the moment it happens, and almost everyone has it. This change blindness test times how long your own eyes take to find one. In Rensink, O’Regan and Clark’s 1997 flicker study, ten observers searched 48 photographs the same way, and some changes took them more than 50 seconds. The result sheet sets your times beside theirs and explains why a blink makes the search so slow.
This test uses the same flicker paradigm. Two versions of a rendered room take turns with a soft grey blink between them; one thing differs, and you tap it the moment you see it. There are eight corners in four steps, from big, bold changes to small ones hidden among look-alikes. Each step pairs a change to the thing the view is about with a change off to the side, Rensink’s two conditions. Each corner is timed up to 30 seconds; a miss counts as 30. Your score is your median time, with your middle-of-the-view and off-to-the-side times set next to the 1997 averages.
It is not a test of eyesight or attention, and it does not rank you: the scenes and timing differ from the 1997 study, so its numbers are reference points, and there is no population data for this room. How long a change takes depends a lot on where you happen to look first. The picture dissolves to grey up to twice a second, softly and without hard flashes; skip this test if flicker affects you.
What the test measures
One thing: how long it takes your attention to land on a change you cannot see happen.
The task
- The flicker paradigm of Rensink, O’Regan and Clark (1997): a scene and a changed copy alternate, with a brief blank between them
- Eight corners of one 3D room, one change each: colour, something appearing and disappearing, or something moving
- Four steps from easy to hard, each with a change in the middle of the view and one off to the side
- Up to 30 seconds per corner; “Show me” appears after 9 seconds or a second wrong tap
Your result
- Your median time to spot a change, and how many of the eight you found
- Your middle-of-the-view and off-to-the-side medians, how the two compare, and the same ratio from the 1997 study
- Your times counted in swaps of the picture, which carry over between setups better than seconds
- Each corner shown afterwards, with what changed
- A share card and a challenge link without spoilers; the link carries only your median and how many you found, in the part after the #
Before you start
- About two minutes
- Flicker notice: soft dissolves to grey, at most two a second, no hard flashes; skip it if flicker affects you
- Works on a phone or a computer. Free, no account; needs 3D (WebGL)
Change blindness FAQ
Is this test free? Do I need to sign up to see my result?
Yes, it’s free, and there’s nothing to sign up for: no account, no email, no payment. Your result appears on this page the moment you finish, and you can share it or play again straight away.
What is a change blindness test?
A change blindness test hides the moment of a change so you have to search for it. In the flicker version, a scene and a changed copy alternate with a brief blank between them. You tap the change as soon as you see it, and the clock records how long your attention took to get there. Why the blank makes that search so much harder is explained on the result sheet, after the eight corners.
How long does it normally take to spot a change in the flicker test?
Several seconds, and sometimes far longer. In Rensink, O’Regan and Clark’s 1997 study, 10 observers took between about 5 and 11 seconds on average, depending on the kind of change, and some changes took more than 50 seconds. Which kind was slower, and by how much, is on the result sheet beside your own times. Their photographs and timing differ from this test, so the figures are a reference, not a norm.
Does it matter where in the room the change is?
The result sheet answers that for you. Each of the four steps has one change to the thing the view is about and one off to the side, of about the same size and contrast, Rensink’s two conditions, and you get a median for each, how the two compare and the ratio from the 1997 study. In this test, which change counts as central or marginal is the site’s own call, made the same way.
Is being change-blind a sign of poor attention or eyesight?
No. Everyone is change-blind under flicker; it is a normal part of how vision works, and the result sheet explains why. Your time depends a lot on where you happen to look first, so this test is not a measure of eyesight, attention or concentration, and it gives no diagnosis.
How is the change blindness test scored?
Each corner is timed from the moment the room appears until you tap the change, up to 30 seconds; a corner not found or shown counts as 30 seconds. Your headline number is the median of the eight times. The labels for fast and slow medians are the site’s own bands, not percentiles, because there is no population data for this room yet.
Is the flicker safe if I am sensitive to flashing lights?
The flicker is deliberately slower than the 1997 study’s three blanks a second: at most two a second, each a soft dissolve to a grey matched to the scene’s own brightness, with no hard flashes. If flicker affects you, skip this test.
Where the numbers come from
The averages are from Experiment 1 of Rensink, O’Regan and Clark (1997): 48 photographs, each shown 240 ms with an 80 ms blank, correct answers from 10 observers. This test uses one rendered room, a slower 520 ms swap and a 30-second limit, so the comparison is a reference, not a ranking. The order of the eight corners follows a design judgement and has not yet been checked against players’ times. The site does not publish its own players’ data.