A number appears, then vanishes. Type it back from memory. One more digit every round.
Most people stop around 7
A number appears on screen for a few seconds, then disappears, and you type it back. Get it right and the next number gains a digit. Longer numbers stay on screen longer, so what is being measured stays memory rather than reading speed.
Most people manage around seven digits. That number comes from George Miller's 1956 paper on the span of short-term memory, and it is roughly why phone numbers settled at the length they did. Getting past it is usually about chunking: nobody holds twelve separate digits, but a handful of three-digit lumps is a different matter.
A number appears for a few seconds, then disappears and you type it back. Get it right and the next number is one digit longer. You get three lives, and a failed round can be retried.
About seven. That figure comes from a well-known 1956 paper by George Miller on the span of short-term memory, and it is roughly why phone numbers ended up the length they are.
Chunking. Nobody holds twelve separate digits, but "four-nine-two" as one lump is a single thing to remember. Saying the digits out loud as they appear also helps most people.
This is verbal memory — what the digits were. The chimp test is spatial memory — where they were. People are often much better at one than the other.
More to play: Chimp Test, Herd Memory, or all solo games.