Drivers on the phone more cautious hands-free
Drivers use "self-regulation" techniques like slowing down when they use their mobile phone hands-free while driving, according to a new QUT study of Brisbane drivers in a high-tech simulator.
But the study found the opposite for drivers who actually held and looked at their phone – they sped up while looking down.
The study analysed the driving performance of 35 drivers aged 18 to 29 in QUT's advanced driving simulator at its Centre for Accident Research and Road Safety-Queensland (CARRS-Q) at Kelvin Grove.
In a paper published online in Accident Analysis and Prevention, the researchers say previous studies of driver impairment while on the phone have not taken into account drivers' ability to self-regulate their behaviour.
Lead researcher Oscar Oviedo-Trespalacios said the self-regulatory behaviour demonstrated in their tests included slowing down while on the phone and keeping very central in the lane.
"But, overall, driving and using a phone still negatively affects both activities," Mr Oviedo-Trespalacios said.
"It's more efficient – and of course safer – to just pull over in an appropriate place to use your phone quickly and then resume your journey."
The simulator tests put drivers through three driving scenarios – driving without using their phone, driving while using their phone hands-free, and driving while holding their phone.
"We found most drivers actually increased their speed while distracted by looking at and holding their phone," Mr Oviedo-Trespalacios said.
The experimental study also found that drivers who held their phones were more likely to use them on the open highway than on S-curves and city roads.
"Road traffic conditions appear to play a vital role in self-regulation of secondary tasks and associated driving performance," the researchers wrote.
The findings of the study can be found online here.
More information: Oscar Oviedo-Trespalacios et al. Driving behaviour while self-regulating mobile phone interactions: A human-machine system approach, Accident Analysis & Prevention (2018). DOI: 10.1016/j.aap.2018.03.020