Ford Motor has designed a light signal system for autonomous vehicles that company officials say helps solve the problem of self-driving cars safely interacting with pedestrians, bicyclists and human drivers.
Looking to prepare for this eventual reality, Ford Motor Company partnered with Virginia Tech Transportation Institute to conduct a user experience study to test out a method for a self-driving vehicle to signal its intent by soliciting real-world reactions from people on public roads.
The white light display, located at the top of the windshield, is designed to communicate intent to yield way or accelerate from a stop, which today is done through hand gestures, head nods and eye contact. 
The cue for yielding to a full stop is two white lights that move side to side.
A rapidly blinking white light indicates the vehicle is beginning to accelerate from a stop, and a solid white light means the vehicle is driving under computer control.
“Understanding how self-driving vehicles impact the world as we know it today is critical to ensuring we’re creating the right experience for tomorrow,” said John Shutko, Ford’s human factors technical specialist

Source: Arab News