Call to arms: a self-driving revolution

Tony Avelar/Associated Press

When it comes to driving, how you interact with the outside world can be as important as how you perceive it.

It's one of the weakest parts of autonomous cars at present. We humans have a whole range of ways of conveying the message "after you" or "thanks", from a brief flash of the headlights or hazards up to slightly more overt physical gestures.