"My memory's just bad"

Underneath a good deal of checking is a belief about yourself. Your memory's poor. Other people can lock a door and know they've done it. You can't, so you have to look. On that view, the checking is a sensible adjustment to a personal weakness.

There are two things to say. The first is that in every experiment described so far, the checkers' memories were fine. Their accuracy didn't drop. Their confidence did. If your memory were bad, the rechecks would sometimes find the door open. Your tally from chapter 1 will tell you how often that happens, and I'd guess the answer is never, or once. That isn't a bad memory. It's a memory you've stopped trusting.

The second is that the belief does damage of its own. Alcolado and Radomsky gave ninety-one students a memory test and then false feedback. Some were told they'd done well. Some were told they'd done badly. Neither was true. Then everyone did two more memory tasks and rated how much they wanted to check their answers. The people who'd been told their memory was poor wanted to check more. Nothing about their memories had changed. What had changed was what they believed about them, and the belief was enough to produce the urge.

So "my memory's bad" isn't a neutral description that happens to lead to checking. It's a cause of checking, on its own, even when it's false. And the checking then fades the picture, which looks like evidence that the memory is bad, which strengthens the belief, which produces more checking. That's a loop with no door in it. The door has been locked the whole time.

I'd invite you to try describing yourself differently, not as a kindness but as a matter of accuracy. You have an ordinary memory that has been told, thousands of times, that it can't be trusted, and has responded by handing every decision to the recheck. Memories that aren't used get quieter. The way to get the trust back isn't to test it more. It's to do the once, properly, and act on it, and let it turn out to have been right, which it will, and let that count.

There's a distinction worth keeping. Some people do have memory difficulties, from illness, injury, medication or age, and for them a check may be a reasonable aid. If you've been leaving things on, or if the forgetting is new and broader than the door, that's a matter for a GP. The habit in this book is one where the memory is fine and the trust has gone.