Using touch to change a tune on Android Auto and Apple CarPlay slows driver reaction times far more than driving under the influence of cannabis and alcohol, according to a new study.
The study by UK road-safety charity IAM RoadSmart found that using touch controls while driving causes a mean increase in reaction times of 53% and 57% for Android Auto and Apple CarPlay, respectively.
Previous studies have found that the mean increase for cannabis impairment is 21%, and 12% when driving with alcohol at the legal limit, the new research highlights.
Surprisingly, using touch controls on infotainment systems also caused greater impairment than using a mobile phone while driving and texting while driving – again, based on data from previous studies.
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Participants in the study were asked to select music on Spotify while driving. The study found drivers underestimated how long they took their eyes off the road when using touch controls.
The impact on reaction times when using voice is significantly lower than using touch on infotainment systems, but still higher than the figures for cannabis and alcohol.
Using voice on Apple CarPlay and Android Auto caused mean increases of 36% and 30%, respectively.
The study found that using either systems' touch controls caused drivers to take their eyes off the road for longer than National Highway Traffic Safety Administration's (NHTSA) recommended guidelines. However, using voice control fell within NHTSA guidelines.
The AAA conducted a similar study in 2018 and found that using Android Auto and Apple CarPlay caused "moderate" levels of driver distraction. They were better than automakers' native infotainment systems, but no system enabled low levels of driver distraction.
The UK study involved 20 participants who used Apple CarPlay and 20 who used Android Auto. Tests were undertaken on three simulated journeys: where the driver didn't interact with any system; when the driver only used voice controls; and where the driver only used touch control.
The test route had three sections where participants were tasked with accessing music on Spotify and BBC radio in different driving conditions. To measure reaction times to an external event, participants were asked to flash their lights on the indicator stalk when a red bar appeared on the screen.
The four measures of driver performance included reaction time to the red bar, driver behavior measures such as speed, lane position and headway, eye gaze, and self-reported performance.
"While drivers reduce their speed to manage this increase in demand, this is not sufficient to compensate for the impact on their driving performance," the report concludes.
"Controlling the vehicle's position in the lane and keeping a consistent headway to the vehicle in front suffered significantly when interacting with the systems, particularly when using touch control."