Colour vision test

All people do not see colours in exactly the same way. There are three types of cells in the human eye which are maximally sensitive to either red, green or blue light. Since many of the genes that determine colour vision are located in chromosome X, possession of only one of such gene can frequently cause an invalid cell type and thus significantly more problems with colours. For example, up to 7% of white males have varying disorders of colour vision, often faulty red or green colour perception. So there should be one man with optimal colour vision in every reconnaissance company, because they spot the enemy in disguise more easily. :)

However, those who like to draw parallels between gender and the animal kingdom can use the fact that the majority of animals have two types of colour vision photoreceptors, but by contrast birds and reptiles have four types. Studies have found that up to 3% of women have, in addition to the three traditional cell types, a fourth cell type, which can theoretically increase their perception of colours. Whether these women know better than others what men want is a question that needs more investigation.