"Everyone checks"

You may have noticed that your partner goes back to the door too. Your mother checks the gas. A colleague admits to reading sent emails. If everyone does it, it can hardly be a problem, and this book is making a fuss about ordinary care.

Everyone does, or nearly. Muris and colleagues asked a hundred and fifty ordinary people about their rituals, and more than half said they had them. Their rituals were less frequent, less intense and less bound up with bad feeling than the compulsions of people with a diagnosis, but in content they were much the same. Checking, ordering, counting, washing. The researchers' conclusion was that there's a continuity between ordinary rituals and clinical ones. It's a matter of degree, not kind. Experts shown the two lists often couldn't tell them apart.

I'd take two things from that. The first is that you're not odd. Checking is one of the most human things there is, and the once is something everyone should do. The second is that the fact that everyone does it tells you nothing about whether it's costing you. Most people do it a little. Some do it a lot. The mechanism in chapter 3 works the same way at every level. A person who rechecks the door once a week is losing a little clarity once a week. A person who rechecks it four times a morning is losing a lot every day, and has noticed the loss and called it a bad memory.

The question isn't whether you check. It's whether the checking is answering the doubt or feeding it. If you check once and leave, and the doubt at the lights is a passing thought, you're fine, and you can stop reading. If you check and the doubt comes back and you check again and it comes back bigger, you're in the loop, and the loop doesn't care that it's common.

There's a line somewhere along this continuum where the habit becomes the condition, and the NHS puts it in terms of time, distress and interference. If checking takes up a lot of your day, causes real distress, or gets in the way of your life, that's the point at which it has a name and a treatment, and chapter 21 says what to do. Most readers of this book are well before that point. But the direction of travel matters, and the direction of a rechecking habit is always towards more.