"New" colours possible?

Mathew Guilfoyle GuilfoyleMR at cardiff.ac.uk
Mon Jan 7 07:35:49 EST 2002

The range of colours that we perceive has obviously been of some use
in our evolution.  The fact that we have not come to separate the
visible specturm into thirty different colours has a reason.  Your
question as to whether we can 'see' new colours glosses over some
major philosophical questions such as qualia.  What I think is really
the question is whether the visual cortex and associated areas can
discern between the wavelength of light incident on the retina to a
greater precision that that to which it is limited by the capabilities
of the retina.  i.e. if we had a better retina could the visual system
decide between more colours.  I prefer Dennett's account of qualia
(i.e. that they don't exist) and would emphasise that the cortex is
simply able to create patterns of neural activity or other process
(protein translation ect..) that differ in response to different
incident light.  Thus a discernment is made.  Whether these would
change our qualia is not a consideration.  We might come to 'know'
there is something different about the colour, which is a different

On the subject of whether there are new colours, the syndrome
synaesthesia as offered some insight.  These patients see colours in
response to visual cues such as typed numbers. i.e. when they see '5'
there is something red about it, even if its black on the paper. 
Ramachandran has reported that some synaesthetes he has studied
experience 'strange' and 'new' colours in response to certain cues. 
You could theorize that patterns that usually go unused by the visual
cortex in normals due to the limitations of the retina are sometimes
inadvertently activated in these patients, giving colour judgements
that most people never have.  Just theory though.

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