Fish in Red Water

A white fish is swimming through the blue-green water. After a short momentt a blue-green fish in red water will appear. How has that happened?

Further material for this article.

Experiment: Fish in Red Water

A White fish is swimming through the Blue-Green water. If you look at the Blue-Green eye for approx. 20 seconds and then look at the Black dot on the right hand side, a Blue-Green fish in Red water will appear.

Why does this happen?

In order to recreate the experiment, save the pattern on your computer and the print it out. Start of by cleanly painting the area surrounding the fish Blue-Green using Pelikan opaque water colours. We can't forget the fishes eye of course, this also is painted Blue-Green.

The second box contains a Black outer lining and a small dot. It is around this point that later the fish will appear to be swimming in Red water.

After the colour has dried, the experiment can begin:
Stare at the Blue-Green eye in the left box for approx. 20 seconds in bright surroundings. After this, fixate on the Black eye of fish in the right box. A moment later you will see a Blue-Green fish swimming in Red water!

After the eye stares at a particular area for a longer period of time, the visual cells tire and become insensitive toward the colour in question. When then staring at the White area, all Green rays contained in the colour White are not recognised by the visual cells. At this moment, the cells only recognise all of the other colours. The area of the eye that visualises the outer lining of the fish, responds by seeing a contrasting colour to Red, in this case: Green. This visual effect can also be created using other colours. This would see Blue become Yellow, Yellow become Blue and Red become Green.

Try it online:
You may also try this experiment right away. Just click here and the experiment can begin.