This week, the BBC Radio 4's Frontiers ran a very interesting special program on the human perception of time. From the program description:
When a person's life is in danger, a phenomenon known as 'time-dilation' can occur. This is when, during a car crash for example, time seems to slow down or become frozen.
In these cases the body's internal clock speeds up when facing a potential catastrophe, so that it can take in more information more quickly and function more effectively in an emergency.
This is also a phenomenon actively sought by elite sportspeople, when they get 'in the zone'.
Link (via Mind Hacks)
