We have this divide in my house. I’m pretty much a typical introverted developer who prefers email and text messages, avoids the phone, and will only use my mobile while driving if something powered by a warp engine lands on the freeway in front of my truck. My wife and daughters, on the other hand, live for social interaction, and think nothing of communicating nearly constantly while driving. Like many other modern drivers, they have convinced themselves that their use of “hands-free” devices renders this mode of communicating safe. Several studies have shown that they, and a lot of other people, are wrong about this. Now we have another.

In a study released today the AAA Foundation for Traffic Safety showed that mental distractions stemming from attempting to communicate with other humans while operating a motor vehicle are just as dangerous whether you’re holding the phone or not. Rating distractions on a numerical scale for risk, the study found that simply listening to the radio was a risk level of 1, which is minimal. Talking on a mobile phone, whether hands-free or handheld, rated a 2. Responding to in-vehicle systems and prompts such as those from navigation or entertainment systems provided the most dangerous distractions of all, meriting a 3 on the AAA scale.

Years ago when I was working on the water I was aboard a large sailing vessel whose captain, a master of ocean-going oil tankers who moonlighted as a square-rig sailor, had very strong opinions about chatting on duty. If you had the helm and he caught you talking to a shipmate you were in for a stern rebuke, at least, and might be dismissed from the wheel and sent to another station. For a large ship, keeping a stable course is a matter of safety and significant amounts of money, and what our captain knew was that people who are focused on a conversation cannot remain attentive to the physical and mental requirements of piloting a vessel.

And they can’t pay attention to driving a car either. There have been enough studies done, and enough research released, that there shouldn’t be any remaining debate here. When you’re driving you’re in charge of a couple of thousand pounds of metal moving at a significant speed. That’s a lot of energy, and it can have devastating consequences when it is not properly controlled. The only responsibility you have when behind the wheel is to exert the proper control to move that chunk of metal around safely. Any conversation, at all, detracts from your ability to do that. End of story. And I really do mean, end of story. Because there is no technology that can change this fundamental characteristic of our brains. Until cars can safely drive themselves, we have to put the phones away and do the driving for them.