Distractions while driving, whether due to chatting with your passengers or your mind wandering, can sometimes be offset by a mechanism in the brain that works as an error corrector. Researchers call it a “sixth sense,” a somewhat unconscious ability to avoid mistakes while on the road. But a new study finds that this sixth sense doesn’t work when you’re texting while driving.

For the study, 59 participants sat in high-fidelity driving simulators where they were given four different driving scenarios. The first was the control, in which they drove under normal conditions, focused and undistracted. The second involved driving while being asked cognitively challenging questions (to render the participants absent-minded), the third involved driving while being asked emotionally-charged questions (to make them emotionally upset), and the final one involved driving while texting.

The participants sat in high-fidelity driving simulators as pictured above, and completed four different driving scenarios in the study. Malcolm Dcosta

As expected, the drivers became more distracted in the non-normal conditions, when they were being pressed with questions or texting. The distractions caused all participants to handle the wheel in a more jittery way, but lane swerving and unsafe driving only occurred among those who were texting. In fact, when the drivers were absent-minded or emotionally-charged, they actually ended up in straighter lines while steering, even if they were jittery with the wheel. And that could be explained by a certain part of the brain which acts as the “sixth sense” in correcting errors.

“A likely explanation for this paradox is the function performed by a part of the brain called the anterior cingulate cortex, or ACC,” said Ioannis Pavlidis of the University of Houston, an author of the study, in a statement. “ACC is known to automatically intervene as an error corrector when there is conflict. In this case, the conflict comes from the cognitive, emotional and sensorimotor, or texting stressors. This raises the levels of physiological stress, funneling ‘fight or flight’ energy to the driver’s arms, resulting in jittery handling of the steering wheel.”

For example, when distracted, drivers get jittery and turn to the left, but the ACC corrects that and creates an equal jitter to the right. All of this happens when a driver is cognitively or emotionally distracted because his or her eyes are still on the road, providing eye-hand coordination. When a phone enters the scene, taking the driver’s eyes away from the road and impairing eye-hand coordination, the ACC can no longer keep things in line.

“The driver’s mind can wander and his or her feelings may boil, but a sixth sense keeps a person safe at least in terms of veering off course,” Pavlidis said. “What makes texting so dangerous is that it wreaks havoc into this sixth sense. Self-driving cars may bypass this and other problems, but the moral of the story is that humans have their own auto systems that work wonders, until they break.”

Plenty of studies have found that texting while driving increases the risk of crashes and other dangerous driving scenarios, but people tend to still do it anyway. Not only do the study’s results reiterate the importance of avoiding texting while driving, they may also provide information for future self-driving car designs.

“Following up on the results of our science study, we are currently looking into the development of a car system to monitor outward driving behaviors, such as steering jitter or lane deviation, as well as the internal state of the driver that causes them,” Pavlidis said. “This system, which I call ‘stressalyzer,’ a play on the word breathalyzer, may serve not only as a ‘black box’ in car accidents, but also as a driver alert and prevention mechanism, since it will continuously sense a driver drifting to distracted mode.”

Source: Pavlidis I, Wunderlich R, et al. Dissecting Driver Behaviors Under Cognitive, Emotional, Sensorimotor, and Mixed Stressors. Scientific Reports. 2016.