How Roadside Safety Signs Backfire—and Why Policymakers Don’t Notice
nudgesYou are driving along the highway and see an electronic sign that reads: “3,238 traffic deaths this year.” Do you think this reminder of roadside mortality would change how you drive? According to a recent, peer-reviewed study in Science, seeing that sign would make you more likely to crash. That’s ironic, given that the sign’s creators assumed it would make you safer.
The study, led by a pair of economists at the University of Toronto and University of Minnesota, examined seven years of traffic accident data from 880 electric highway sign locations in Texas, which experienced 4,480 fatalities in 2021. For one week of each month, the Texas Department of Transportation posts the latest fatality messages on signs along select traffic corridors as part of a safety campaign. Their logic is simple: Tell people to drive with care by reminding them of the dangers on the road.
But when the researchers looked at the data, they found that the number of crashes increased by 1.52 percent within three miles of these signs when compared with the same locations during the same month in previous years when signs did not show fatality information. That impact is similar to raising the speed limit by four miles or decreasing the number of highway troopers by 10 percent.
The scientists calculated that these messages contributed to 2,600 additional crashes and 16 deaths annually. They also found a social cost, meaning the financial expense borne by society as a whole due to these crashes, of $377 million per year, in Texas alone.
The cause, they argue, is distracted driving. Much like incoming texts or phone calls, these “in-your-face” messages grab your attention and undermine your focus on the road. The signs are particularly distracting and dangerous because, in communicating that many people died doing exactly what you are doing, they cause anxiety. Supporting this hypothesis, the scientists discovered that crashes increase when the signs report higher numbers of deaths. Thus, later in the year, as that total mortality figure goes up, so do the percentage of crashes.
Boomerang effects happen when those with authority, in government or business, fail to pay attention to the science. These leaders rely on armchair psychology and gut intuitions on what should work, rather than measuring what does work.
That change over time is not simply a function of changing weather, the study’s authors observed. They also found that the increase in car crashes is greatest in more complex road segments, which require greater focus to navigate.
The overall findings represent what behavioral scientists like myself call a “boomerang effect,” meaning an intervention that produces consequences opposite to those intended. Unfortunately, these effects are all too common. Between 1998 and 2004, Congress funded the $1 billion National Youth Anti-Drug Media Campaign, which famously boomeranged. Using professional advertising and public relations firms, the campaign bombarded kids aged 9 to 18 with anti-drug messaging, focused on marijuana, on TV, radio, magazines, and websites. A 2008 study funded by the National Institutes of Health found that children and teens saw these ads two to three times per week. However, more exposure to this advertising increased the likelihood that youth used marijuana. Why? Surveys and interviews suggested that young people who saw the ads got the impression that many of their peers used marijuana. As a result, they became more likely to use the drug themselves.
Boomerang effects happen when those with authority, in government or business, fail to pay attention to the science. These leaders rely on armchair psychology and gut intuitions on what should work, rather than measuring what does work.
To be clear, message campaigns—whether on electronic signs or through advertisements—can have a substantial effect on behavior. Extensive research reveals that people can be influenced by “nudges,” which shape the environment to influence their behavior in a predictable manner. For example, a successful campaign to reduce car accidents involved sending smartphone notifications that helped drivers evaluate their performance after each trip. These messages informed drivers of their personal average and best performance, as measured by accelerometers and gyroscopes. The campaign, which ran over 21 months, significantly reduced accident frequency.
Nudges work best when rigorously tested with small-scale experiments that evaluate their impact. Because behavioral scientists are infrequently consulted in creating these policies, some studies suggest that only 62 percent have a statistically significant effect. Other research reveals that up to 15 percent of desired interventions may backfire.
In the case of roadside mortality signage, the data are damning. The new research based on the Texas signs aligns with several past studies. For instance, research has shown that increasing people’s anxiety causes them to drive worse. Another, a Virginia Tech study in a laboratory setting, found that showing drivers fatality messages increased what psychologists call “cognitive load,” or the amount of information your brain is processing, with emotionally-salient information being especially burdensome and preoccupying, thus causing more distraction.
Nonetheless, Texas, along with at least 28 other states, has pursued mortality messaging campaigns since 2012, without testing them effectively. Behavioral science is critical here: when road signs are tested by people without expertise in how minds work, the results are often counterproductive. For example, the Virginia Tech research looked at road signs that used humor, popular culture, sports, and other nontraditional themes with the goal of provoking an emotional response. When they measured how participants responded to these signs, they noticed greater cognitive activation and attention in the brain. Thus, the researchers decided, the signs worked. But a behavioral scientist would note that increased attention likely contributes to the signs’ failure. As the just-published study in Science makes clear, distracting, emotionally-loaded signs are dangerous to drivers.
But there is good news. First, in most cases, it’s very doable to run an effective small-scale study testing an intervention. States could set up a safety campaign with a few electric signs in a diversity of settings and evaluate the impact over three months on driver crashes after seeing the signs. Policymakers could ask researchers to track the data as they run ads for a few months in a variety of nationally representative markets for a few months and assess their effectiveness. They could also ask behavioral scientists whether their proposals are well designed, whether similar policies have been tried previously in other places, and how these policies have worked in practice.
Everyday citizens can write to and call their elected officials to ask them to make this kind of research a priority before embracing an untested safety campaign. More broadly, you can encourage them to avoid relying on armchair psychology and to test their intuitions before deploying initiatives that might place the public under threat.
A sleek, four-foot tall white robot glides across a cafe storefront in Tokyo’s Nihonbashi district, holding a two-tiered serving tray full of tea sandwiches and pastries. The cafe’s patrons smile and say thanks as they take the tray—but it’s not the robot they’re thanking. Instead, the patrons are talking to the person controlling the robot—a restaurant employee who operates the avatar from the comfort of their home.
It’s a typical scene at DAWN, short for Diverse Avatar Working Network—a cafe that launched in Tokyo six years ago as an experimental pop-up and quickly became an overnight success. Today, the cafe is a permanent fixture in Nihonbashi, staffing roughly 60 remote workers who control the robots remotely and communicate to customers via a built-in microphone.
More than just a creative idea, however, DAWN is being hailed as a life-changing opportunity. The workers who control the robots remotely (known as “pilots”) all have disabilities that limit their ability to move around freely and travel outside their homes. Worldwide, an estimated 16 percent of the global population lives with a significant disability—and according to the World Health Organization, these disabilities give rise to other problems, such as exclusion from education, unemployment, and poverty.
These are all problems that Kentaro Yoshifuji, founder and CEO of Ory Laboratory, which supplies the robot servers at DAWN, is looking to correct. Yoshifuji, who was bedridden for several years in high school due to an undisclosed health problem, launched the company to help enable people who are house-bound or bedridden to more fully participate in society, as well as end the loneliness, isolation, and feelings of worthlessness that can sometimes go hand-in-hand with being disabled.
“It’s heartbreaking to think that [people with disabilities] feel they are a burden to society, or that they fear their families suffer by caring for them,” said Yoshifuji in an interview in 2020. “We are dedicating ourselves to providing workable, technology-based solutions. That is our purpose.”
Shota Kuwahara, a DAWN employee with muscular dystrophy. Ory Labs, Inc.
Wanting to connect with others and feel useful is a common sentiment that’s shared by the workers at DAWN. Marianne, a mother of two who lives near Mt. Fuji, Japan, is functionally disabled due to chronic pain and fatigue. Working at DAWN has allowed Marianne to provide for her family as well as help alleviate her loneliness and grief.Shota, Kuwahara, a DAWN employee with muscular dystrophy, agrees. "There are many difficulties in my daily life, but I believe my life has a purpose and is not being wasted," he says. "Being useful, able to help other people, even feeling needed by others, is so motivational."
When a patient is diagnosed with early-stage breast cancer, having surgery to remove the tumor is considered the standard of care. But what happens when a patient can’t have surgery?
Whether it’s due to high blood pressure, advanced age, heart issues, or other reasons, some breast cancer patients don’t qualify for a lumpectomy—one of the most common treatment options for early-stage breast cancer. A lumpectomy surgically removes the tumor while keeping the patient’s breast intact, while a mastectomy removes the entire breast and nearby lymph nodes.
Fortunately, a new technique called cryoablation is now available for breast cancer patients who either aren’t candidates for surgery or don’t feel comfortable undergoing a surgical procedure. With cryoablation, doctors use an ultrasound or CT scan to locate any tumors inside the patient’s breast. They then insert small, needle-like probes into the patient's breast which create an “ice ball” that surrounds the tumor and kills the cancer cells.
Cryoablation has been used for decades to treat cancers of the kidneys and liver—but only in the past few years have doctors been able to use the procedure to treat breast cancer patients. And while clinical trials have shown that cryoablation works for tumors smaller than 1.5 centimeters, a recent clinical trial at Memorial Sloan Kettering Cancer Center in New York has shown that it can work for larger tumors, too.
In this study, doctors performed cryoablation on patients whose tumors were, on average, 2.5 centimeters. The cryoablation procedure lasted for about 30 minutes, and patients were able to go home on the same day following treatment. Doctors then followed up with the patients after 16 months. In the follow-up, doctors found the recurrence rate for tumors after using cryoablation was only 10 percent.
For patients who don’t qualify for surgery, radiation and hormonal therapy is typically used to treat tumors. However, said Yolanda Brice, M.D., an interventional radiologist at Memorial Sloan Kettering Cancer Center, “when treated with only radiation and hormonal therapy, the tumors will eventually return.” Cryotherapy, Brice said, could be a more effective way to treat cancer for patients who can’t have surgery.
“The fact that we only saw a 10 percent recurrence rate in our study is incredibly promising,” she said.