Drivers may do well to hang up the phone and listen to an audiobook instead. Talking can trigger brief delays in eye movements that may slow reaction times and impede hazard detection, new research suggests.
While previous studies have shown that increasing cognitive load — such as taking a call — can impair driving performance, a study published in PLOS ONE has linked conversation to slower reaction times and changes in rapid eye movement. The effects are subtle but could build up, impairing driving ability and undermining public safety, researchers say.
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Talking Versus Listening in the Car
In the study, 30 participants were asked to look at a peripheral visual target appearing in one of eight directions. The volunteers were measured on speed and accuracy, and performed the task under three conditions: talking, listening to audioclips, and none of the above (control).
During the talking condition, participants were quizzed on general knowledge and asked a set of pre-determined questions, ranging from “Where is the capital of Italy?” to “What color shirt did you wear yesterday?” Meanwhile, the listening round involved passages from the Japanese classic, I Am a Cat, a satirical novel.
The study produced clear results. All thirty volunteers demonstrated delays across three types of gaze under the talking condition. This included the time required to respond, move to, and stabilize gaze on the target. In contrast, no delays were detected in the listening condition when compared to the control condition.
“These results indicate that the cognitive demands associated with talking interfere with the neural mechanisms responsible for initiating and controlling eye movements, which represent the critical first stage of visuomotor processing during driving,” lead author Shintaro Uehara, an associate professor at Fujita Health University in Japan, said in a statement.
Under the talking condition, participants took, on average, 279.7 milliseconds to react to the target, versus 260.4 milliseconds and 261.3 milliseconds in the listening and control conditions, respectively. More noticeable were the differences in the time to move to and stabilize gaze in the talking condition (260.1 milliseconds and 1226.5 milliseconds) compared with the listening (141.5 milliseconds and 493.2 milliseconds) and control (160.8 milliseconds and 548.9 milliseconds) conditions.
Encouraging Safer Driving Practices
The researchers report that this highlights the impact of talking — and the cognitive load required when searching for answers — on eye movements, which, in turn, can impair driving technique and delay response times when reacting to hazards, such as a pedestrian crossing the road. This, they point out, is not to say that slower eye movement is the only — or even the most important — cause of slower reaction times when driving.
“For instance, a braking reaction would be delayed while talking even under a situation where a driver is staring at the taillights on a lead car, due to hindered visual encoding by the distraction of attention (i.e., inattentional blindness,” the researchers wrote.
There are additional questions to answer, such as at what point does increased cognitive load hinder reaction times and interfere with eye movements?
“Additionally, the question of whether the effect is primarily due to the talking behavior itself or the cognitive load associated with talking remains unresolved,” the study’s authors added. But the researchers hope it could contribute to discussions on how to promote safer driving practices and may encourage drivers to be more mindful when it comes to talking behind the wheel.
Although this study took place in a controlled setting and did not involve a real-world driving scenario, previous research has linked cellphone use to car accidents. According to several studies, including one in BMJ, using a cell phone while driving can increase the likelihood of crashing as much as fourfold — even when using a hands-free device.
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Article Sources
Our writers at Discovermagazine.com use peer-reviewed studies and high-quality sources for our articles, and our editors review for scientific accuracy and editorial standards. Review the sources used below for this article:
This article references information from a recent study published in PLOS One: Talking-associated cognitive loads degrade the quality of gaze behavior
This article references information from a recent study published in BMJ: Role of mobile phones in motor vehicle crashes resulting in hospital attendance: a case-crossover study
