Of the people surveyed:
- 20% claim to use turn signals all the time (Group A)
- 80% admit to not using them all the time (Group B)
- 0% claim to never use them (Group C)
Now, I believe there are people in Group C, though I haven't met any (self-admitted, that is). I also believe the pool I found is somewhat skewed, because these are all people close to me, and I usually hang out with considerate people who drive reasonable vehicles and understand that the road and everything on it does not belong to them.
I also searched to see what had been written already about this topic. I should have known that Don Norman had an article about signals. His take is more on how we might get our machines to be as expressive as human faces, but I was intrigued by the bits about the importance of signals in communication and understanding.
When I cycled to work the last two summers, I noticed that the other cyclists smile, wave and greet each other while commuting. I had people ask if I need help when I was fixing a chain. I remember growing up in small-ish towns where people would drive down the main streets and wave to each other.
This doesn't happen in our cars any more. Our obscenely big-assed cars have so many amenities that we have grown accustomed to treating them as isolated bubbles of human existence--an extension of our private living space.
But they're not. We are interacting with the world when we are piloting a moving vehicle among moving vehicles with other pilots.
So, dude: use your turn signal.