why do we see things as colourful

Question: why do we see things as colourful
- Keywords:
  neuroscience
Asked by louismart to Lyn, Katy, Paul, PB, Ruth on 25 Jun 2013.
- Katy Brown answered on 25 Jun 2013:
  
  We use cells in our eyes called cone cells. We use the retina, at the back of the eye to see. This has two types of cell – rod cells, which work well without much light but can’t detect different colours, and cone cells which need more light but are used to see colour – this is why you can see less colour in dim light. There are three types of cone cells with red, blue and green pigment and each picks up a different colour. When light of the right colour hits the cell, the pigment degrades and sends messages to the brain which are interpreted as colours. When the colour goes away, the pigment reforms.
  Most animals have bad colour vision, but humans, some other primates and some marsupials. It is likely that primates living in trees developed colour vision to help them pick out fruit in trees, then passed this on to humans.
- Paul Waines answered on 25 Jun 2013:
  
  I think Katy has answered this very well. All I can add is that the colour of an object is affected by the way in which light interacts with its surfaces, as well as the way we perceive it.
  
  if someone is colourblind, then they are not actually blind but are unable to perceive certain colours. It is most common in men and happens because the cones that Katy refers to aren’t developed properly.
- Ee Lyn Lim answered on 25 Jun 2013:
  
  Katy’s given a brilliant answer! I don’t have any more to add to that, except a question that I’ve wondered about since I was little – how do you know the ‘red’ you see is the same as the ‘red’ everyone else sees? Or is it that we’re taught that a particular colour we see is called ‘blue’, when actually the pictures that our brains see are completely different? When people match outfits that, to you, seem to clash horribly, is it just because they like it that way, or is it because their brain genuinely sees shades that go well together?
  
  I can’t think of any way to compare the colours that different people see, and it doesn’t really matter anyway (as long as we can all agree that apples are red and oranges are orange) – but it’s a little weird to think that your world might be coloured completely differently from someone else’s!
- Peter Balfe answered on 25 Jun 2013:
  
  Interestingly, colour perception is one of the most variable features of vision in mammals, given that we all hear, smell, taste, etc. it seems remarkable that so many mammals have lost the different rod and cone cells in their retinas which are the key to colour vision. There are rodents with essentially no colour vision whereas there are very similar ones with highly developed colour senses, the differences being in which ones are nocturnal.
  The reason is probably cost, the extra brain power needed to process and interpret colour images is thought to be high and unless there’s an advantage it won’t evolve.

Question: why do we see things as colourful

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