Which of the cubes has an irregular colour?
How it works:
1. Click on the box that has an irregular color compared to the rest of the boxes.
2. The test starts when you click on the first box.
3. You have 15 seconds to decide on each grid.
4. When you click the wrong box you will lose 3 seconds.
Human can distinguish colours when incoming light reacts with the cone cells in the retina of eye.
There are three types of cone cells. Based on how they respond to light of wavelengths you will perceive the three basic colours; red, green and blue. The rest of the colours are perceived as a result of your brain combining the different cone cells.
Often it is claimed that women distinguish colours better than men. This is partly true since 2-3 % of women have also fourth type of cone cells instead of the normal three.
This is called tetrachromacy. A person like this can distuinguish up to 100 million different colour tones.
HOW ANIMALS SEE COLOURS
Birds are famous for their excellent eyesight. Their eyes can see even five basic colours and the number of different colour combinations is vast.
Bees and many other insects can see ultraviolet light. That helps them to notice which plants are full of nectar and need pollination.
In most mammals' eyes there are less cone cells than in human's eyes which makes them see a smaller-scale colour spectrum. Many mammals hunt at night when it's more important to distinguish shapes than colours.
Marine fish register only blue and green light. In turn, fish living in lakes and rivers see shades of red.
WHY ARE SOME PEOPLE COLOUR BLIND
Some people have colour blindness. It is notably more common amongst the men: in research it's been found that 8 % of men are colour blind as opposed to only 0,4 % of women.
Colour blindness is caused by lack or defectiveness of cone cells in the retina of eye.
For a colour blind person some colours look misleadingly similar. The most common form of colour blindness is deuteranomaly, a difficulty to distinguish red and green.
Please notice that on this page you can't test colour blindness, but your ability to differiate colour tones.