Using a hands-free device to talk on a cell phone while driving may not increase safety, according to a new research study.

The National Highway Traffic Safety Administration released on Thursday, June 9, its study titled “Driver Distraction Research on the National Advanced Driving Simulator.” The study found that using a headset and voice-activated dialing “degraded both driving performance and vehicle control.”

Other recent research has shown that it is the thought process involved with talking on a cell phone while driving that causes distraction, regardless if a hands-free device is used.

Researchers in the NHTSA study said that voice-activated dialing often leads to longer dial times, which offsets any benefit those devices may provide when it comes to keeping eyes on the road.

The research also shows that improperly designed headsets can actually introduce new problems into drive-and-talk scenarios.

“Headsets or earbud devices that do not fit securely, or that do not provide sufficient volume, may cause the driver to manually adjust the device, or even hold it tightly to their ear during conversation,” the research said. “Such a poorly designed device is no longer ‘hands-free’ and becomes a new source of distraction and annoyance.”

The study contradicts safety laws that have already gone into effect in New York and New Jersey – and another one that has been sent to the governor in Connecticut – that require drivers to use hands-free devices to talk on the phone in their cars.

Also, a recent study by the University of Utah found that drivers between the ages of 18 and 25 move and react more slowly when talking on a phone and driving at the same time, regardless of the use of their hands.