Coined by linguist Arnold Zwicky, 'frequency illusion' expresses the sense that suddenly everyone is thinking what you're thinking. If you're considering retraining as a teacher, everyone you meet seems to have the same idea. You want to buy the latest hybrid and there it is in every newspaper you open. Indeed, every other car that passes is a hybrid, just like the one you've homed in on - even in the same colour. Once we focus our minds on an idea, object or issue, it's uncanny how soon the world seems to mirror our views. An extension of narcissism, frequency illusion puts us at the centre of the universe. It might be great to confirm a purchasing decision (see, everyone is wearing black this season) but it can get a bit dodgy in the workplace. Trying to prove we're right because the last three people we saw in the lift seem to agree with us is a sketchy way of conducting research. Besides, frequency illusion happens when we're looking for our views to be mirrored. The only remedy for this common and potentially dangerous disorder is to ask for proof. Just because you bought a pair of skinny jeans does not mean 'everybody' is buying them. The everybody bit gets us out of the hard work of having to think (and decide) for ourselves.