Seatecho

Seatecho (n.) is the warmth that stays behind in a seat after somebody has left it. You spot an empty seat on a crowded bus. You make your way to it with quiet triumph. You sit down, and there it is: the unmistakable, faintly personal warmth of the person who was sitting there a moment ago. It is not a lot of heat. It is, however, entirely too much.

The seatecho is a strange thing to object to. The same person who will happily warm their hands on a mug, snuggle under a heated blanket or stand gratefully in front of a fire will recoil from a warm chair as though it had said something rude. On a freezing winter morning, with frost on the windows, a seatecho still manages to feel like an intrusion, a sort of invisible handshake nobody asked for.

There are recognised techniques. The hover involves sitting down very slowly and very slightly, as if lowering oneself into a hot bath. The pause involves standing near the seat for a moment, looking out of the window and letting the echo fade before sitting. The switch, used only in desperate cases, involves choosing a different, colder seat further away, even if it faces backwards and is next to someone eating crisps.

The seatecho is at its most powerful in certain places. Toilet seats in public buildings are the obvious champion. Office chairs come a close second, particularly when a colleague has just borrowed yours. Cinema seats produce a mild seatecho that tends to be forgiven, because the lights are going down and nobody can see your face.

There is one great exception. A seatecho left by somebody you love is not a seatecho at all. A cat's warm spot on the sofa, a child's place at the kitchen table or a partner's side of the bed can feel like a gift rather than an invasion. The warmth is exactly the same. It is only the name on it that has changed.

The real thing behind the word comes down to physics and feelings. The warmth lingers because the fabrics and foams used in most seats are poor conductors of heat. They soak up warmth from a body slowly and then give it back slowly too, so a cushion can stay noticeably warm for a little while after someone stands up, while a hard plastic or metal seat cools much more quickly.

The feeling is harder to measure, but psychologists who study disgust have noted that people are often uneasy about traces left by strangers' bodies, such as warmth, smells or used objects, even when those traces are perfectly harmless. It seems to be a quiet, automatic way of keeping a little distance from people we do not know. So the next time you hover above a warm seat, you are not being silly. You are simply following a very old instinct, a few centimetres above a bus seat.