Editing Stimulus modality (section)

===Colour stimuli===
Humans are able to see an array of colours because light in the visible spectrum is made up of different wavelengths (from 380 to 760&nbsp;nm). Our ability to see in colour is due to three different [[cone cells]] in the retina, containing three different photopigments. The three cones are each specialized to best pick up a certain wavelength (420, 530 and 560&nbsp;nm or roughly the colours blue, green and red). The brain is able to distinguish the wavelength and colour in the field of vision by figuring out which cone has been stimulated. The physical dimensions of colour include [[wavelength]], [[intensity (physics)|intensity]] and purity while the related perceptual dimensions include [[hue]], [[brightness]] and saturation.<ref name=Carlson />

Primates are the only mammals with colour vision.<ref name=Carlson />

The [[Trichromatic theory]] was proposed in 1802 by [[Thomas Young (scientist)|Thomas Young]]. According to Young, the human visual system is able to create any colour through the collection of information from the three cones. The system will put together the information and systematize a new colour based on the amount of each hue that has been detected.<ref name=Carlson />