Reading this NYT article about radar to cover car blind spots, which describes a system that will trigger lights in the rearview-mirror when cars are in the blind-spot, reminded me of an old idea I had some time ago I called "Eyes in the back of your head."

The idea would be to wear a special collar while driving. This collar would contain small electrodes that could lightly stimulate the skin on the back of the neck. Perhaps just one row, but ideally a small 2-D image should be possible.

This would be connected to a camera, radar or sonar system pointing back from the vehicle. It would map where other vehicles are, and turn that into an image on the back of the neck.

Thus, as a car came up behind you and passed you, it would feel like something brushing the back of your neck on one side.

I was inspired to this by reading about a system for the blind that mapped a video camera image onto a 2000 pixel electrode map on the stomach. It was found that over time, the nerves would retrain and a sort of limited vision could develop. Might this have application in driving, or perhaps combat?Of course there are many things to work out. Would the feeling on the neck just be disconcerting, and not so useful? Or would we learn with just a small period of training to really feel as though we had a sense of not just what is in front of us but what is behind us? How much spatial sense would we develop about the distance and closing speed of the cars coming at us?

The system would also have to be 100% accurate at spotting cars, because we might start even ignoring the rearview mirror. If it missed a car that could be big trouble. It would have to work all hours of the day, and if it ever stopped working it would need to signal an alarm to warn the driver to go back to the old system.

Thus while cameras would be cheap (put 1 or 2 cameras at 2 different but nearby focus settings. Items that are blurry are far away, items that are sharp -- that are not your own car -- in one of the 2 views are closer to you.) Radar or sonar might be better.

I could also see this for military applications, to give a figher a sense of what's behind him or her. One could even imagine a portable pack for the commando, though power requirements would be an issue.

Another alternative would be to research what can be communicated with stereo sound. We already use sound to sense and locate moving objects behind us in a simple way. Might it be possible to turn a computer's knowledge of the nearby cars into something our auditory system would interpret as somebody coming up behind us? That is nice because it could just be speakers on the headrest, no collar needed.

Update: Here's a project doing some work in this area -- people find it quite intuitive!

Hmm, I'm writing a lot about transportation this month!