Can you stop yourself thinking about a white bear?
Paradoxical effects of thought suppression
People told not to think about a white bear kept thinking about it, and rang a bell every time they did.
Participants spoke their thoughts aloud for five minutes, but were told not to think about a white bear. Each time one popped into their head, they had to ring a bell.
The bell rang a lot. Even worse, people who had first tried to suppress the bear thought about it even more afterwards. You are now thinking about a white bear. Sorry.
The surest way to summon a bear is to ban it.