Last year saw the largest jump in fatal car crashes of the past half century: Estimates pinned the total number of deaths from traffic accidents in the U.S. at more than 38,000 in 2015, and serious injuries at around 4.4 million. The National Safety Council, which published the numbers earlier this year, also listed a few recommendations in their report for how to cut down on dangerous driving: buckle up, avoid driving while sleepy, appoint a designated driver. None of them, clearly, was particularly groundbreaking — and as Science of Us has previously reported, awareness campaigns that relentlessly hammer on the same points don’t really do much to change behavior.
What’s more, “cutting down on dangerous driving” may be too fuzzy a concept for public-health officials to meaningfully tackle. Not all risky drivers are created equal, after all — some are speeders, some are drinkers, some are otherwise reckless or distracted or tired. And what if different people are motivated to drive dangerously for different reasons? That’s the suggestion of a recent study in the journal PLoS One, and if it bears out, it could lead to improved interventions to keep drivers safe.
To better understand what drives dangerous behavior on the roads, the study authors developed distinct psychological profiles for three different types: drivers who’ve racked up multiple DUIs, drivers with frequent speed violations, and drivers who’ve gotten in both types of trouble. They recruited men between the ages of 19 and 39 from each of the three groups, specifically looking at people who’d had at least two DUI arrests in the past ten years; at least one DUI arrest and one other traffic violation in the past two years; or at least three traffic violations unrelated to alcohol in the past two years (men from the same age-group with clean driving records acted as a control group).
The researchers ran the participants through a series of tasks designed to test their inhibition levels, reaction time, decision-making skills, and propensity for risk-taking. They also gave the men personality tests, documented their history with alcohol and drugs, and measured their levels of the stress hormone cortisol by taking saliva samples before, during, and after a stressful timed-math exercise.
When the they crunched the numbers, they found measurable differences among the driver types. Compared to the safe-driving control, the DUI group showed lower levels of inhibition, had a greater history of alcohol abuse, and — a little more surprisingly — were the most averse to risk of all the drivers. The traffic-violation group had ”greater sensation seeking, disinhibition, disadvantageous decision making, and risk taking.” The mixed group, meanwhile, showed “more substance misuse, and antisocial, sensation-seeking, and reward-sensitive personality features.” Interestingly, all three groups also showed less of a spike in cortisol during the stress.
The study was short on specifics as far as how to apply these findings, but broadly speaking, the psychological classification system “appears to be a useful marker for clarifying explanatory pathways to risky driving, and for research into developing more personalized prevention efforts,” the authors wrote. In the meantime, it may also help road-safety groups tailor their programs to the issues specific to their region. North Dakota, for example, has the most drunk-driving fatalities per capita, and Wyoming takes first places for fatal accidents caused by speeding; what works in one place may be less effective in another, and one strategy for cutting down on driving deaths may be to focus on the psychological mechanisms behind dangerous driving behavior. Or, as study co-author Thomas Brown, a psychiatry professor at McGill University, said in a statement, “If we and they don’t understand their behaviour, how can they be expected to change it effectively?”