Tail light" Neat Lighting Trick?

I went to the races last week saw a gsx that had a pretty neat tail light wiring job done. If you aren't familiar with the tail lights its three bulbs on each side "(b b b) center piece (b b b)" When he hit the brakes the center light would stay dim and the outter lights brightened.
"(!B! b !B!) center piece (!B! b !B!)" Any idea how this is done please post. Thanx

He disconnected the brake signal to the light.

i got behind an eclipse today wiht euro lights and when the guy turned, the two lights took turns flickering... it was one of the coolest things ive seen. the lights would go from (O o) to (o O) then back and forth. anyone know how to pull this off?