Owners of used cars in New York and New Jersey may want to think twice before conducting an important business call while driving. A new study has found that operating a vehicle can significantly impair one’s ability to speak and comprehend language.

Researchers at the University of Illinois tested participants’ ability to listen to and retell stories that they had never heard before as a passenger and as a driver. The study found that a participant’s ability to recall information declined significantly if he or she was also driving during the exercise.

The results suggest that a driver remembers 20 percent less of what is told to them while behind the wheel compared to times when they are simply sitting still. Researchers also found that drivers were least accurate in retelling stories that were communicated to them while navigating through intersections or demanding traffic conditions.

“This study shows that various aspects of language go to hell when you’re driving,” said psychology professor Art Kramer, who collaborated on the study.

Although older subjects performed more poorly on the control test than their younger peers, their ability to retain information while driving worsened at the same rate.