The experience I had in 1998 on the San Bernardino Freeway near downtown L.A. (which was 10 to 15 seconds before a crash that wrecked the car I was in), was analogous to that of a little switch in my brain being flipped and events of the external world slowing down.
Now there's a relative thing involved, here. If my perception of time speeds up (my personal second becomes shorter), the external second--which is the rest of the world--becomes longer, and hence the events of the world seem to slow down.
But, along with this, the sense of anxiety disappears. I felt totally objective with no sense of emotion.A dispassionate, external, observer who could some how stretch out the external sequence (subjectively)to make the available time as long as necessary.Rather than being paralyzed by fear, as the common expression goes, the exact opposite was true,I felt no fear or inhibition whatever.You must realize that I knew full well I was in the midst of a potentially fatal accident, but I was completely detached. There is a curious analogy to having one's wind knocked out in a fall--for a few seconds you don't know if you will ever be able to take another breath, but somehow it doesn't matter,and even seems mildly ironic(!)
I think I can convey this better by taking a chance with technical inaccuracy: Let's say my brain was temporarily running at a faster processing speed.
As Rainman noted, this phenomenon has no effect on actual external time, and I don't believe you can physically move faster.
Lynn Dickey, former GB quarterback in referring to his own experiences with this phenomenon, and making reference to Reggie Jackson --a famous slugger of October--said the pitched balls "must have looked like basketballs coming at him."