Psychologists say repeatedly checking locks or appliances is not making memory stronger, but can reduce confidence in what you remember, according to Behavior Research and Therapy

You are halfway down the driveway when it hits you. Did I really turn the stove off? You walk back in, check it, see that it is off, and walk out again. Two minutes later, the thought creeps up again. Anyone who has ever gone back to check a lock or an oven more than once knows how convincing that nagging doubt can be.

It turns out that the checking may be part of the problem itself. In a study titled ‘Repeated checking causes memory distrust,’ published in Behavior Research and Therapy, psychologists Marcel van den Hout and Merel Kindt of the University of Amsterdam found that repeatedly checking something doesn’t sharpen your memory of it. Instead, it quietly chips away at your confidence in your own memory, even when that memory is technically accurate.

The virtual stove experiment
According to the same study, the researchers wanted to understand a puzzle common to obsessive-compulsive disorder, or OCD: why do people who check things over and over still feel unsure afterwards, rather than reassured? To test that, they built an interactive computer animation of a gas stove and asked healthy adult volunteers to perform checking rituals on it in two experiments with 39 and 40 participants each. In each case, all volunteers took the same memory test before and after the task. One group was checking out the virtual stove, while a control group was checking something unrelated, virtual light bulbs.

The results were consistent across both experiments, the study found. In fact, the stove-checking group’s memory was just as good as the control group’s; they did not actually remember it any less accurately than the other group. But their memories faded, became less detailed, and much less reliable, while the light bulb group showed none of these effects.

Ruling out a simple explanation
According to the study, one could argue that the before-and-after design skewed things, since the control group may simply have expected a memory check and thus remained more alert. To rule this out, the researchers ran a third experiment with another 40 volunteers, split into two groups of 20, and skipped the first memory test altogether. But the result was the same: the stove-checking group again had non-vivid, non-detailed memories and low confidence compared with the light bulb group.

Why checking backfires
The study says the reason is less about memory failure and more about how the brain processes something seen too many times. The more you examine something, the more familiar you become with it; this familiarity pushes the brain in the direction of abstract conceptual thought, away from close attention to sensory detail, like the way a knob looked or felt when it was turned. That drop in sensory detail makes the memory seem thinner, less convincing, even if it is not actually wrong.

This is something to sit with, particularly for anyone who considers themselves a chronic double-checker. Checking a locked door three times before a trip, or rereading a sent text five times, wondering if you hit send twice, could be a very millennial and Gen Z habit. This study shows that habit does not protect your memory. If anything, it may be working against it.

A pattern seen beyond the lab
This is not an isolated finding. In a follow-up study by researchers Adam Radomsky, Philippe Gilchrist, and Dominique Dussault, titled ‘Repeated checking really does cause memory distrust,' the authors tested 50 undergraduates in a standardized ritual: one group repeatedly turned a real stove on and off and checked it, while another performed the same sequence on a faucet. After 19 checking trials, only the stove group reported significantly less confidence, vividness, and detail, strengthening the case that repeated checking itself undermines memory trust.

The pattern also fits what clinicians observe in people with checking compulsions. Checking rituals, whether they are about locks, switches, or appliances, are often fueled by a desire to avoid a feared outcome and nagging uncertainty that a task was completed properly, says the International OCD Foundation. The irony is that the checking that was supposed to clear up that doubt may be precisely what perpetuates it.

What this means for the rest of us
To be clear, this does not mean checking your stove once or twice is harmful or that everyone who double-checks a lock has OCD. The original study used healthy adult volunteers and a virtual task, not a clinical population, so it can’t capture all real-world checking habits. But it provides a handy, evidence-based reason to think twice before going back for that fourth or fifth check.

If you’re stuck in a loop of checking and re-checking, the most reassuring step may be to do the opposite of what your instincts suggest. Check once, pay close attention while you do it, and then trust it. But going back to the same place again may only leave you less certain than when you started.