Phone use while driving is one of the most dangerous distractions because it affects attention in several ways at once. Even a brief look at a phone takes your eyes off the road at the same time your mind focuses on reading or composing a message.
Many drivers believe that voice calls or hands-free features make phone use safe while driving. Research does not fully support that belief. While hands-free calling keeps your hands on the wheel, it still creates significant mental distraction — the cognitive demand of following a conversation competes directly with the attention needed to drive.
The conversation the phone creates is the problem, not just the physical act of holding it. A driver talking on the phone — even through a hands-free system — misses hazards that a driver not using a phone would notice.