Drivers using a hands-free phone are just as distracted and potentially dangerous as those holding a device in their hand, according to a new British study.

According to researchers at the University of Sussex, conversations may cause drivers to visually imagine a subject. It’s this process that involves a part of the brain normally used to watch the road.

RELATED: NY sees 840 percent increase in texting-related traffic tickets since 2011: Cuomo

The study involved 20 male and 40 female volunteers who took part in lab-based tests. Participants were put through a range of simulated situations, such as responding to hazards, like pedestrians stepping into the road, and driving while being distracted by a human voice. 

“Those having a hands-free conversation that sparked mental imagery took around 0.65 seconds longer than undistracted participants to react to hazards that appeared in the side area of the driving situation,” said research leader Gemma Briggs. 

“At 30 mph, that’s an extra stopping distance of 8.7 meters (28.5 feet). They took even longer to react to hazards that appeared directly ahead of them — around 0.98 seconds longer than undistracted drivers. We found that drivers distracted by conversation also looked at hazards but failed to react to them, even when they were presented directly ahead of them.”

However, talking to passengers in a car has no negative effects. Scientists believe this is because they are in a shared environment with the driver, and therefore have the ability to regulate conversation if necessary. 

RELATED: New photo appears to show Boston-area police officer texting and driving 

Chatting on the phone, regardless of whether you have a hands-free kit, can result in a failure to detect hazards, slower reaction times, and a reduced awareness of what is going on around you.

“Our study highlights a misunderstanding implied by current legislation in many countries — the notion that hands-free conversation equates to ‘safe’ driving,” Briggs added. “There are significant differences between talking to a passenger and talking hands-free and people need to be aware that their driving may be compromised when they pay attention to other tasks.”

—Dmitry Belyaev