If you would replace your small car with a bigger one, would you become a more reckless driver?
Prior research seems to suggest that you would, but the evidence is not conclusive. We know that people tend to choose bigger cars because they feel more secure, but also that these cars are more likely to be involved in accidents. This implies that big car owners take more risk.
It still does not necessarily mean that bigger cars cause reckless driving. A simple alternative explanation is that reckless people would be prone to buying bigger cars.
The car cushion hypothesis
To establish causality, one needs to run an experiment, which is what Bart Claus from IESEG in Paris and I did in a recently published study. We developed what we termed the “car cushion hypothesis”, which suggests that bigger cars not only make people feel more secure, but also affect their behavior by increasing their risk-taking.
In our first experiment, we invited people to a professional driving simulator developed for Toyota. We told them that they would be either driving a smaller car (Toyota Yaris), or a large car (Toyota Avensis). Both groups were instructed to drive naturally along a predetermined route with average traffic density, with other cars, cyclists, and pedestrians. The system registered the driving behavior.
We did find, indeed, that the larger car affects reckless driving: the large car drivers drove faster, accelerated more, decelerated later, used their brakes more, and so on.
Compared to the small car drivers, their behavior was more dangerous to themselves and to others. This experiment shows the causal effect of car size on driving style. Participants were randomly assigned to the Yaris or the Avensis: their personality (like ‘being a risk seeker’) can not explain the difference.
Push it to the limit
In our second experiment, we wanted to test participants’ penchant for risk-taking beyond driving. Using the established BART test (Balloon Analog Risk Task), participants were asked to inflate a balloon by pushing a button. They received a small monetary reward for each successful push but lost all their winnings if the balloon popped.
First we gave people pictures, text and video about either a large Mercedes (C-class) or a small Mercedes (A-class), and they were instructed to vividly imagine driving that car. People who were assigned the C-class, inflated their balloons more than those imagining driving an A-class. This suggests that perceived car safety on the road can be linked with generalized risk-taking.
We concluded that big cars do serve as a ‘cushion’, making drivers feel more secure and inducing them to take more risk.
The public policy implication is that incentivizing against bigger cars can have a double benefit: it can reduce accidents by reducing reckless driving, and it would reduce the severity of accidents, because smaller cars cause less damage to others. Policymakers should take this into account when working to reduce the societal and public health impact of road accidents.
While we wait for the policymakers to do their part, we can also hope that the emergence of self-driving car technologies eventually will help us solve this important issue altogether.
Claus, B., Warlop, L. The Car Cushion Hypothesis: Bigger Cars Lead to More Risk Taking—Evidence from Behavioural Data. Journal of Consumer Policy 45, 331–342 (2022). https://doi.org/10.1007/s10603-022-09511-w