I ran some tests back in the late 80's that might interest people:
There was a section of weaving road through a forested area of light and shadow.
Wearing dull colors which were popular for road cyclists at the time:
I noted that traffic approaching from the rear would come very close to me, notice me and you could hear them veer away at the last second. I was catching them by surprise.
Wearing bright colors such as reds and yellows:
You could hear the traffic approach and you could hear them veer away further back but nevertheless often I would be catching them by surprise.
Wearing Dayglow:
I NEVER heard the veering of their wheels. They noted the presence of a bicyclist from as far back as they could see me and would have planned to pass safely so that they didn't need to veer away at all.
Over the intervening years the contrast is somewhat less because autos are more used to seeing cyclists these days, but the basic premise still is there. Very bright dayglow colors allow the car drivers to see you at a much greater distance and in varying lighting conditions and hence allow them to plan and pass more safely.
This doesn't change the actions of driving jerks mind you who will STILL pass closely.
And it doesn't change the reactions of drivers of questionable skill who will stare at a bicyclist when passing because they want to make sure that they give clearance. What you look at you will steer much closer to, so these people will unwittingly (nitwittingly?) pass much closer than necessary.
But when drivers know you're there it absolutely gives you improved chances of not being struck accidently.
Due to drivers being more used to cyclists these days I often wear just normally bright colors but whenever there's the chance of reduced visibility I always wear dayglow.
What's more, the most easily seen color by men is PINK! I assume the same applies for women. Pink is a color that doesn't occur very often in nature and so men can see it a very great distance away even in quite small portions. I could probably make a crass comment about that but I won't.
So I have dayglow yellow-green jackets and vests and when I can get them dayglow orange. Every once in awhile you can find a dayglow version of blue or red such as "electric blue" or some such. But not very often. Actually I'm sort of surprised that dayglow colors for foul weather gear are so limited.