Drivers can be distracted for as long as 27 seconds after performing activities such as changing music or dialing a phone number, even when using hands-free technologies, according to a study by the AAA Foundation for Traffic Safety.
The results raise "new and unexpected concerns" about the use of phones and vehicle information systems while driving, the non-profit group, part of the AAA motoring organization, said in a report released on Thursday.
"The results indicate that motorists could miss stop signs, pedestrians and other vehicles while the mind is readjusting to the task of driving," AAA Foundation Chief Executive Peter Kissinger said in a statement.
Even using voice-activated technologies such as Apple's Siri and Microsoft's Cortana pose hidden dangers for drivers, the study found. Among these hands-free technologies, Google Now achieved the best rating, meaning it was the least distracting.
Among vehicles tested, the least level of distraction was seen in General Motors' Chevy Equinox while the highest was in Mazda Motor Corp's Mazda 6.
Automakers and technology companies such as Apple Inc , Google Now maker Alphabet Inc and LG Corp are counting on demand for complex vehicle communications and entertainment systems to help boost growth.
However, road safety concerns could result in greater regulatory scrutiny of such systems.
The research was carried out by Dr. David Strayer and Dr. Joel Cooper of the University of Utah.
A total of 257 drivers aged 21-70 participated in the study of 2015 model-year vehicles, while 65 additional drivers ages 21-68 tested Siri, Cortana and Google Now.