Also known as 'prosopagnosia', face blindness means the inability to recognise faces even though your eyesight is perfectly good. We know it all too well from the drinks party circuit, and everyone suffers from it at some point, especially when the really boring colleague is heading your way in the office. Bosses tend to suffer the disorder acutely when they get in lifts with eager members of the personnel department. Some say this is a serious condition requiring treatment, which is convenient for those who would rather chew off their own foot than do small talk in corridors. Also known as 'cutting people dead', prosopagnosia is best treated with American tail-wagging friendliness. Just say 'How are you?' then move on before they can respond. Face blindness is also the favourite disorder of celebrities. They are so used to being pestered by members of the public that any excuse to fob off the publicist or photographer is welcome. Of course, one could always admit to short-sightedness - but that is hardly Hollywood.