The Yellow We Both Mean

I was writing the colour block for lemon and I stopped in the middle of the sentence. It had come out without any hesitation: the yellow of zest, not the yellow of the fruit. Then I read it back and asked by what right. I have never met the woman who will read it. I have no idea what her kitchen smelled like when she was nine. So on what basis was I telling her what a smell looks like?

The companion piece to this one, Half Chemistry, Half Autobiography, argued that most of what a smell makes you feel is your own history, and I stand by that. It left a thread hanging, because it also allowed that some of the shared claims hold. This post is about which ones, how far they go, and what they permit a description to do.

There is a body of experimental work on crossmodal correspondences, much of it from Charles Spence's lab at Oxford, on the way one sense reaches across for another. The finding people quote most is the shape one. Given a spiky form and a rounded form, participants put lemon and pepper with the spiky, raspberry and vanilla with the rounded. Odours have been matched to musical pitch with the same kind of agreement, by people who have no obvious reason to agree with each other.

I like that result and I want to be honest about its size. The shape study ran twenty-five participants on twenty wine smells. The analysis put intensity and pleasantness at the centre of it: the more intense a smell was, and the less it was liked, the more angular the form it pulled. So what we share may be plainer than a mapping from lemon to spike. It may be that our senses broadly agree about how intense a thing is, how heavy, how bright, and that the shape follows from that.

Colour is the more interesting case, and the one I actually needed. There are more than twenty published studies on the colours people put with smells, and inside any one group the answers hold together. They are not random. Run the same test across cultures and it loosens. One study gave the same fourteen odours to Dutch, German, Malay, Malaysian-Chinese, American and Netherlands-resident Chinese participants: consistent inside every group, different between them, and some pairs of groups much further apart than others. In another, pineapple came out reliably yellow for Taiwanese participants and red for many of the French. Researchers in the field now treat learned association as the dominant explanation.

Which means the shared layer is not wiring. It is the residue of a shared world, shared because we grew up among the same fruit and the same cleaning cupboards and the same words for them, and it runs exactly as far as that overlap does: a household, a region, a generation.

The shared layer is exactly the size of a shared world.

That is better news than universality would have been. Universality would have made every product page a claim about everybody. Nobody can check a claim like that, and it breaks the first time one reader disagrees. What I have instead is smaller. It holds up better.

So that is what the pages are built on. Colour, texture, sound, architecture: all of it describes the thing in the air, its weight, its edge, how far it travels, whether it lies low or runs along the ceiling. That is the part I can speak to, because it is the part we mostly hold between us. A description is a doorway. What it means once it reaches you was never mine to answer, and the other post is where that half lives.

When I write these blocks I am picturing a room I would have to be able to draw. A kitchen at nine in the evening, washing-up done, one lamp on. A scent in that room has a reach, a height, a length of stay, and those are facts about the air that I can be held to. Whether the room then feels like relief or like the front edge of a Sunday you are dreading depends on nine at night in every other kitchen you have ever stood in.