Take our word for it, there are 12 black dots in this image.
But your fiendish brain will not let you see them all at the same time.
Why? Is there a moratorium on seeing black dots? A world shortage of bullet points? Has Studio Ghibli enlisted them all as soot sprites?
The frustrating image was tweeted by games developer Will Kerslake on Sunday, and has enjoyed viral success since then.
Amid much head-scratching, Reddit user MaconStreet’s following explanation appears to be one of the more plausible: “Because of the surprisingly poor resolution of human vision, and the tricks the brain uses to compensate for it.
“You can only see precisely enough to see the black dots at a fairly narrow area near the centre of your field of vision, so you can only make them out near where you’re currently looking.
“Your brain gives you the sense that it’s sure the black dots you aren’t currently looking at aren’t there because of the strength of the grey pattern. It sees the pattern (it’s good at seeing patterns) in the area you’re currently looking at, sees that the nearby areas (which it has a lower resolution of) have a similar pattern, and extrapolates. Because most of the intersections of lines don’t have black dots, the extrapolated pattern you perceive doesn’t include them.”
An explanation regarding a similar image was offered by the journal Perception in 1999.
It stated: “When the white disks in a scintillating grid are reduced in size, and outlined in black, they tend to disappear. One only sees a few of them at a time, in clusters which move erratically on the page. Where they are not seen, they grey alleys seem to be continuous, generating grey crossings that are not actually present. Some black sparkling can be seen at those crossings where no disk is seen. The illusion also works in reverse contrast.”
Glad we’ve sorted that out then.