No, sorry - they are motion sensors. I can trigger them on my bike, with no lights involved. You're suffering from confirmation bias, and not taking into consideration the fact that the lights change when they detect your vehicle, this is usually going to be coincident with you flashing your headlights, but the former is the cause, not the latter. It's a common misunderstanding, though.
If it's dark and quiet, I think both sides go to red, then when a light is detected, that side goes green. Quite common knowledge in the UK