someone wrote:

Sometimes I might agree with you but for the fact that I've survived
without any daytime lights, and the times I have been struck, the
invisibility cloak took charge because of what I believe is a lack of
apparent threat or movement. I believe that although the flash may
attract the attention of a driver for a split second, it is not long
enough for him to assess the probability of another road user. He
will still look through the cyclist because he is small and apparently
immobile. A pair of alternating lights to the front and to the rear
would likely have greatest effect (there are legality issues with this
due to it being used by police etc.) Using leg bands does seem to
have prevented the smidsy scenario with me. I've stiched 4" white
collars below my knees on my black tights. I also move from side to
side to improve conspicuity when safe and desirable.

Actually, what seems to have the greatest effect on drivers, is the
Bike-Up Flash Flag. This may be partly due to the fact that it's so
unusual, but it really does get in the face of drivers coming up behind
you, and coming toward you.

"http://www.flashback.ca/bicycle.html"

When I'm driving, I find the flashing high-intensity LED strobes from
oncoming cyclists extremely visible.