Embodied Language New College, Oxford 27 th September 2011 Nick Unwin ‘The Language of Colour: Neurology and the Ineffable’

The Hering colour circle There are four ‘unique hues’ - yellow, red, blue, and green. These hues look essentially unmixed. There are also four ‘binary hues’ – orange (reddish yellow), purple (bluish red), turquoise (greenish blue), and chartreuse (yellowish green). These hues look essentially mixed. (See C.L. Hardin, Color for Philosophers, Hackett 1986) However, there are ‘spectral opponences’ between red and green and between blue and yellow. This means that there can be no reddish greens or yellowish blues (except in extraordinary circumstances).

Warm versus cool hues Some hues (red, orange, yellow) seem intrinsically warm (“advancing”, “positive”); other hues (blue, turquoise, green) seem intrinsically cool (“receding”, “negative”). There are cultural and physical associations here, but also (it seems) pure phenomenology. © 2006, Nicholas Unwin warm cool neutral Perception of red/yellow involves excitation of neural pathways; of green/blue, inhibition. Perhaps this excitation and inhibition has a wider physiological impact, which would explain these phenomenological features.

Simple red-green (r-g) inversion involves reflection in the vertical axis ‘Diagonal’ (d-) inversion involves reflection in the dotted axis Red is thus exchanged with yellow, and green with blue. Orange and turquoise stay fixed. Hue-inversions (aka inverted spectra/qualia) Unique (binary) hues stay unique (binary), and warm (cool) hues stay warm (cool), thus ensuring that d-inverts are less easily detected than r-g inverts. © 2006, Nicholas Unwin

An illustration of red-green and diagonal inversions

How does redness relate to warmth? A purely external relationship due to ordinary physical associations plus some cultural conventions.

How does redness relate to warmth? A purely external relationship due to ordinary physical associations plus some cultural conventions. An internal phenomenal connection, but a shallow one. The residue formed from subtracting warmth from redness could be combined with coolness to produce a cool red hue (Joseph Levine, ‘Cool Red’, Philosophical Psychology 4 (1991): 270–40). Thus explaining why redness is typically combined with warmth does not explain why red looks red.

How does redness relate to warmth? A purely external relationship due to ordinary physical associations plus some cultural conventions. An internal phenomenal connection, but a shallow one. The residue formed from subtracting warmth from redness could be combined with coolness to produce a cool red hue (Joseph Levine, ‘Cool Red’, Philosophical Psychology 4 (1991): 270–40). Thus explaining why redness is typically combined with warmth does not explain why red looks red. An internal phenomenal connection, and a deep one. Warmth is not all of redness (otherwise yellow could not also be warm), so a residue possibly exists. But this residue is not pure redness, but only half a colour. If combined with coolness, the residue will yield not red, and a fortiori not cool red, but a wholly alien (and unimaginable) hue.

How do words like ‘warm’ function? ‘Warm’ is a purely metaphorical term (as in a ‘warm’ greeting) It is a literal term, and has the same meaning as in ordinary, tactile cases: visual and tactile warmth are the same quality Something in between

How do we choose our phenomenological vocabulary? Ask ordinary language users about which terms seem appropriate.* Look for neural links with different areas of the brain, and let the neurology guide the vocabulary. A combination of the two. (*See Lars Sivik, ‘Color systems for cognitive research’, in C.L. Hardin and Luisa Maffi (eds), Color Categories in Thought and Language (CUP, 1997) 163–93.)

Illustrations Holy Island, Northumbria; with red- green and diagonal inversions. © 2006, Nicholas Unwin

Illustrations (3/6) Abbey at Lindisfarne, Northumbria; with inversions. © 2006, Nicholas Unwin

Illustrations The Backs, Cambridge, seen from Clare Bridge; with inversions. © 2006, Nicholas Unwin

Illustrations Rivington reservoir, near Bolton; with inversions. © 2006, Nicholas Unwin