Repetitive indication of one's next destination
* Even if a driver does something that other drivers don't like, using a turn signal is a way to cooperate. It would be nice if drivers could say, "We agree that this is the way that we will drive." But often, people drive in different ways. But at least drivers are able to say, "We agree that this is the way that we will communicate while we drive."
* As technology increases, will turn signals ever become obsolete? For instance, will vehicles have devices that send out laser messages when they are turning that are holographically projected onto other vehicles' windshields? Perhaps a robotic voice will accompany. "Vehicle on the right is turning right." In the meantime, turn signals are a good, old-fashioned way to communicate.
* Four-way blinkers are a very interesting use of turn signals, I think. A right turn signals means, "I am turning right." A left turn signal means, "I am turning left." But both a right and left turn signal mean, "I am not going anywhere." Indeed, if one tried to go both right and left at the same time, they probably wouldn't go anywhere.
* How easy it is to not use one's turn signals? (I do it more often than I am willing to admit.)