Most people will have observed the often impressive synchrony of the behaviour of fish in a school or birds in a flock. The fact that the behaviour of a fish is so well matched to that of the behaviour of others is straightforward: perception directly affects behaviour. When a fish perceives a change of direction in another fish it simply matches this change in direction. This direct link between perception and behaviour can be easily witnessed in humans as well. We too match the behaviour of others and we do this simply because perception directly affects action. The specific behavioural changes perception can bring about differ between humans and fish, but the underlying mechanism is essentially the same. Perhaps we share this important psychological mechanism with a haddock (Dijksterhuis 2001, p 105)
