Take the test (need Flash):
http://www.dothetest.co.uk/
and from the website:
The aim of our Cycle safety campaign is to reduce the number of cyclists
that are hurt on London's roads.
Imagine...
A passer-by asks you for directions. As you talk to him, two workmen
walk between you carrying a door. In a flash the passer-by switches
places with one of the workmen, and you are left giving directions to a
different person. Do you think you would notice?
Researchers at Harvard University played this trick on some unsuspecting
people and over 50 per cent failed to spot the change.
This phenomenon is known as "change blindness" - only a tiny fraction of
all the information going into your brain enters your consciousness.
People often fail to see a change in their surroundings because their
attention is elsewhere.
Even stranger, if you are concentrating on something, you can become
blind to other events that you would normally notice. This "inattention
blindness" is possibly the reason why motorists collide with cyclists.
Just as it is important for road users to keep an eye out for cyclists,
cyclists must also take steps to ensure they are seen by motorists.
http://www.tfl.gov.uk/corporate/projectsandschemes/roadsandpublicspaces/7599.aspx