What Are Turn Signals For?

Is it really a “Big Question” to ask, “What are Turn Signals For?” Yes. This question offers a microcosm of communication and misunderstanding.

The California Vehicle Code Section 22107 says: “No person shall turn a vehicle from a direct course or move right or left upon a roadway until such movement can be made with reasonable safety and then only after the giving of an appropriate signal in the manner provided in this chapter in the event any other vehicle may be affected by the movement.”

Section 22108 says: “Any signal of intention to turn right or left shall be given continuously during the last 100 feet traveled by the vehicle before turning.”

Note two key phrases: “after the giving of an appropriate signal.” And “during the last 100 feet traveled by the vehicle before turning.”

In other words, you are supposed to signal well before actually turning or changing lanes. To me this seems obvious: It signals an intention of what is to come next. I learned this from my excellent driver ed teacher Wes Abrams at Kennedy High School in Maryland.

But that is not what I observe here. People don’t signal what they intend to do. Instead, they signal as they are doing the actual turn or lane change. I regularly see a person stopped at an intersection for no apparent reason. They are waiting for a break in traffic to make their left turn. When the break comes, they simultaneously start to turn and engage their left turn signal. What exactly is the point of this signaling?

Consider how it is for me riding a bicycle on a street with dedicated right turn lanes. I am in a bike lane approaching this dedicated right turn lane. Here is what I see most of the time: A motorist comes up on my left and cuts directly across my path toward the dedicated right turn lane on my right. Causing me to brake to avoid a collision.

The motorist then continues in the right turn lane. Just before making the right turn, he or she flips on the right turn signal while starting the right turn. What was that even for? You just crossed one or more lanes, possibly endangering people, without giving any signal. Why signal after it no longer matters?

There is an entire field called “semiotics” devoted to the meaning of signs and signals. I hoped to find a research paper on the semiotics of turn signals, but I found nothing.

Turn signals are meant as a form of communication from one person to another. But they serve another, less obvious purpose: They are a form of commitment for the motorist preparing to turn. A reminder that what you are about to do affects other people.

Should you in fact wait to be sure that some “other vehicle may be affected by the movement” as the law requires? Why bother? It is the pedestrian, bicyclist, motorist, or even horse rider who you don’t see who needs your signal more than anyone. When you are planning a lane change or turn, why not use your turn signal automatically without wasting mental effort to decide if it is “necessary”?

One key point I am trying to convey: Think about how your actions may affect others. Imagine you are rolling a two-ton boulder in someone’s path. Use some form of communication to signal your intention.

But there is a second point: The message you are receiving may not be the one that was sent. I am expecting to receive a signal indicating “I am planning to turn across your path soon.” But the sender was sending a completely different message: “I am already in the process of cutting across your path now.”

Imagine how often this occurs with all communication?

I will end with a third “Big Questions” point: “Theory of Mind.” Theory of Mind is the ability to put yourself in the position of another person. You have stopped in the middle of the road for no apparent reason. What is the other person supposed to make of this? How is the other person supposed to know that you are about to cut in front of them? What will the other person feel if you cut in front of them without giving a signal?

I will revisit Theory of Mind in a future article. For now, perhaps you can just follow the law and use your turn signal to communicate your future intent to turn or change lanes?