What is a common mistake drivers make when turning?

Not signaling at all is a common mistake drivers make when turning because proper signaling is essential for communicating intentions to other road users. When a driver fails to signal their upcoming turn, they create uncertainty for other drivers, cyclists, and pedestrians, which can lead to accidents and confusion. Signaling not only helps ensure the safety of the driver making the turn but also allows others to adjust their actions appropriately, promoting smoother traffic flow and reducing the likelihood of collisions.

In the context of the other options, while turning their heads excessively might be distracting, it is not as fundamentally critical as the act of signaling. Using the wrong turn signal can also cause confusion, but it typically occurs less frequently than the complete failure to signal. Ignoring traffic lights is a serious violation that affects right-of-way rules and is addressed through other traffic regulations.