The Dangers of Double-checking

Kathleen McGowan

Checking and rechecking fogs the memory, making it harder to recall specifics and leaving your memory in doubt.

Did I remember to turn the stove off? I'll check one more time. Do I still have the plane tickets with me? I'd better look again. Did I remember to lock the front door? I should really get out of bed and make absolutely sure.

We all feel the need to double-check sometimes, to reassure ourselves that we didn't overlook something crucial or neglect a possibly dangerous problem. When we're under pressure or worried about something, it's especially common to double- or even triple-check. That's normal, but for many people, the habit of repeated checking becomes a dangerous and undermining habit.

For people with obsessive-compulsive disorder, checking can consume hours every day, driven by intense fears of unlikely scenarios. A teacher continually searches the floor, obsessed with the idea that a dropped needle or pin lurking in the carpeting might injure her students. A man spends two hours every morning verifying that all the doors, windows and electrical plugs of his apartment are normal before he leaves for work.

These are extreme cases. But mildly anxious or worried people may get caught in similar unhappy loops. "If I look once more," they tell themselves, "I'll be sure everything is OK."

Yet the double-checking doesn't solve the problem. People feel better for a moment, but soon the worry creeps back—and builds. Doubt grows: did I really turn off the burner? The worrier searches his mind, and finds only uncertainty.

Why does double-checking backfire? According to psychologist Adam Radomsky of Quebec's Concordia University, repeated checking actually fosters doubt by making it harder to remember.

In one study, his team of researchers asked ordinary college students to first turn off, then repeatedly check an electric stove set up in the testing lab. Afterward, the students were asked whether or not the stove had been turned off, how clear their memory was of the situation, and how sure they were that they remembered accurately what had happened.

Students who checked the stove 10 or 15 times correctly remembered that it was off—but the memory was nowhere near as vivid, and they had much less confidence in their own memory. Because of the checking, they began to doubt what they had seen with their own eyes.

"The more you check something, the less vivid and less detailed it is, and the less confident you are in your memory," says Radomsky. "Checking, which is supposed to make you more confident in what's going on, makes you less confident."

Double-checking fogs memory because instead of a clear, memorable, one-time occurrence, the checker is confronted with a series of similar events that tend to blur together. It's much harder to recall the specifics after repeating the same action 10 or 15 times. That's when doubt sneaks in.