birding-aus colour perception

Subject: birding-aus colour perception
From: John Leonard <>
Date: Wed, 16 Jun 1999 09:02:29 +1000
As I understand it there is no reason to think other than that everyone,
everywhere who has normal eyesight sees exactly the same the colours as
everyone else. BUT different langauages divide the spectrum up differently,
so what is green in one language is classed under blue in another.
Interestingly languages the world over seem in recent times to be converging
on the spectrum as divided up in English, for example in Medieval Welsh most
of the dull blue colours were called either grey or green, in Modern Welsh
the word for blue has been extending its range to include those colours
which in English are classed as blue. Another consideration is that some
langauges have distinctions that are not found in English, Latin, for
example, had two words for white, candidus, meaning bright, shining white,
and albus, meaning ordinary dull white. (Conversely in some languages there
are few colour terms, and colours are expressed by saying that something is
'ash-coloured', or 'ochre-coloured' and so on).

And then there is individual preference within a language: I am always
having arguments with people about colours, because I prefer to call a lot
of the duller blues, green or turquoise (perhaps my Welsh descent!).

But there is another consideration too: when we look at a bird, depending on
the time of the day and the atmospheric conditions, we see different
colours, for example a Golden Whistler at dawn is actually reflecting light
at a different wavelength from its belly-feathers than it does at midday.
However if we are familar with the bird, our brain forms a mental image of
the bird, with the yellow at a kind of average value, and that's what we
'see'. (This applies to everything we commonly see, and a mental image of a
new object or class of objects is very soon produced by the brain). Of
course the brain can't manipulate the data it recieves from the optic nerves
when conditions become too extreme, which is why you can't 'see' a Golden
Whistler's colours when there not enough light to see any colour. But this
explains why when you're out in the early morning there is certain point at
which suddenly you can begin to see colours, or conversely suddenly you
can't see colours at night?it's not that at a certain point there is enough
light, or not enough light, but at a certian point the brain receives just
enough data to make it think that it wouldn't be too disorienting to switch
on the images, or with the evening example there comes a point at which
there is too little data for it to make sense to keep on 'seeing' the mental
image any longer.

This explains that strange feeling people get soemtimes, when, in poor
light, you see a bird you can't identify and you are completely mystified as
to what it is, and then suddenly you recognise it and it 'turns into' a
familalr species. It also explains why beginning bird-watchers have so much
difficulty 'seeing' birds that, to us, are really obvious?they have not yet
formed a mental image of that species, and don't know what to look for.

Which brings us on to colour charts. What I"ve been talking about so far has
to do with birds in the bush, rather than in the hand, and I suspect that
those of us who are not experienced bird-banders, as I am not, would find it
quite disconcerting at first to see birds in the hand, they would not 'look
right'. However experienced banders would have assimilated the look of the
bird in the hand to their mental image of one in the bush and would find
little incongruity, I suspect. The difficulty would be, as Ros Laudon
pointed out, that the colours on the cards are printed on a material that is
quite different in texture from feathers, and as such personal preference,
and the light at the time of the comparison would tend to have an effect,
and this, I would suspect, would make such colour comparisons subjective, as
you are not comparing like with like, you are trying to compare a
well-established mental image with a recent perception.

John Leonard

John Leonard (Dr),
PO Box 243,
Woden, ACT 2606,

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