How does the dot counting test work?
A group of 1 to 9 dots flashes up for 250 milliseconds, about a quarter of a second, and then disappears. You answer how many there were, by tapping a number or pressing it on your keyboard. There are 18 rounds: every number from 1 to 9 comes up twice, in random order, and never the same number twice in a row. A small cross holds the center for 0.8 to 1.3 seconds before each flash.
How is your result calculated?
Your result is how many rounds you got right, out of 18. Each answer is also timed, from the animation frame that draws the dots to the moment your key or finger goes down, using the timestamp your browser gives the press. The dots are taken down 250 milliseconds after that same frame, so every round shows them for the same time.
Your results are split in two: 1 to 4 dots, and 5 to 9 dots. Comparing the two halves of your own run is the interesting part, for the reason below.
Why are small numbers so easy?
Up to about four, most people don't count dots at all: they see "three" at a glance, quickly and almost without mistakes. Beyond that, a quarter of a second isn't long enough to count, so larger numbers have to be estimated from the overall look of the group, and answers get slower and less accurate.
That instant recognition of small numbers is called subitizing, from the Latin for "sudden". The word was introduced by E. L. Kaufman and colleagues in a 1949 paper in the American Journal of Psychology on how people judge the number of dots shown briefly.
What can change your result
- Where you look. The dots appear around the center. Keeping your eyes on the cross means you aren't moving them when the dots arrive.
- Patterns. Some groups happen to form familiar shapes, like the five on a die, which makes them easier to read at a glance.
- Your screen. A screen that responds slowly can smear the dots, and every display shows them for whole refresh cycles, so the exposure can be a few milliseconds longer or shorter than 250.
- Keyboard or touch. Number keys need no aiming; tapping a button does, which adds to your time but not to your mistakes.
This is a game about how we see quantities, not an assessment of anything, and results from different devices aren't directly comparable. To keep track of things that move instead, try Multiple Object Tracking.