Huh. I couldn't find anything in a quick google either ... any traffic engineers or optometrists here?

It's so commonplace in motor vehicle and traffic applications though. Four way flashers for slow vehicles. Blinking yellow traffic lights at intersections as a warning to use caution. How we all learned in driver's ed to pulse our brakes to alert following motorists when we have to stop or slow quickly but not with absolute maximum braking power. Those new(ish) stop signs surrounded by blinking red LEDs. The way the walk sign starts blinking when it's counting down to red. True, as cyclists we know to be very skeptical of what car people think is safe ... but considering that blinking is what they use to attract each other's attention, I'm inclined to take it on faith.