You will see a coloured square with two squares beneath it. One of the two matches the one on top exactly. Your job is to say which, as quickly and accurately as you can.
There are 72 of these, in three short stretches, and then twenty quick colour judgements. It takes about four or five minutes. Some stretches ask you to hold something in mind while you do the colour task.
Your responses are recorded anonymously — no name, no login, nothing that identifies you. What is recorded is which square you picked and how long you took. Afterwards you will see what the original 2007 study found.
Best on a laptop with a keyboard, in ordinary room light. If your screen has night mode or automatic brightness turned on, turning it off will make the colours truer.
SESSION 2026-08-24