This post also has flashing images. If those are not your thing, please be a grownup and go to a different web site. Or, be a mature grownup and go outside, far away from the computer. Chase a stick or something.

If you are still here: brain blue yellow is like brain red green. It looks like two colours you know well, but combines them in a way they cannot be combined using only the normal building blocks of colour, which are: a) light, and; b) your retinas.

A lot of what your retinas do is tell your brain the ratio of blue light to yellow light they’re getting. It’s blue vs yellow, in opposition, or maybe even as enemies. They are not allowed to get along, according to light and your retinas.

But your brain is a brain genius and loves to imagine peaceful coexistence, when nudged. Your brain is lucky to have hot sandwich to nudge it.

In the flashing image below, just like in the brain red green image, there are two squares, each with an x in the middle. Stare at the x’s and let your focus slip, until the two appear to merge into a single x. Hold that, and feel your retinas getting tired, and notice the fringe of afterimage around the one square surrounding the one x.

Your brain will fight you on this one, will try to tell you you’re seeing either blue or yellow, and you will notice spontaneous patterns of lines and even plaids emerging from the confusion.

Hang in there and let the brain blue yellow come to you. When you see it, you’ll know, because it will look both blueish and yellowish without being green, and because the words you might use to describe it will fall out of your vocabulary.

Strain for words. Find a way to describe brain blue yellow. Write the words down. In the virtual spaces of the future, walls will be painted this colour and you’ll want to be able to tell your friends how to find you.

Below these words is a faster version of the same animation (24-ish frames per second rather than the ten above). If you felt at all bad staring at the slow one, please pass on the quick one. But if brain blue yellow was hard to see above, you may have an easier time with quicker strobing.

Once there was a kid who could only see in black and white but who had no trouble finding words for brain colours.

You will be like that, sometime soon.