Before you read what's below, do the test in the following video, and pay close attention!
This is a recent commercial part of the London Transport ad campaign, aimed at reducing the number of cyclists that are hurt on roads. It is quite an interesting test, and really goes to show that human perception is not as dependable as we'd like to think. Only a portion of what you see actually enters your consciousness. From a legal standpoint, this test questions the reliability of eye-witness testimonies.