On a long weekend drive to my kid’s sporting event, I found myself doing exactly what most people around me were doing: cruising along at a few miles over the posted limit. It wasn’t a rebellious act, just the kind of quiet, almost unconscious rule-bending that feels normal on an open highway. But then there were the outliers—the ones who blasted past in the left lane, weaving between cars, clearly unconcerned with speed limits, safety, or the police cruisers that might be lurking behind a hill. I didn’t follow suit. I valued my license too much, and frankly, the thought of an accident was enough to keep my foot steady on the pedal. Still, I couldn’t help but notice how their behavior altered the feel of the whole drive. Suddenly the road seemed wilder, more lawless, and for a moment, the social contract that keeps us all moving together felt a little more fragile. That feeling, it turns out, is not just a personal impression—it’s backed by science. Researchers at the University of Amsterdam and their colleagues published a study on October 21 in Proceedings of the Royal Society B suggesting that a handful of genuinely deviant individuals can undermine the cooperative norms of an entire group. Lucas Molleman, a psychologist at the University of Amsterdam, put it memorably: the truly deviant among us “basically take off the guardrails of the group.”
The study itself began with a cleverly designed thought experiment, one that aimed to understand what pushes ordinary people to bend or break rules. To make the stakes feel real and emotionally charged, the researchers deliberately chose a contentious moment: the week before the 2024 U.S. presidential election. They recruited 750 American participants, roughly evenly split between Democrats and Republicans, and asked them to complete a simple online task. Each participant watched an animated shooting star streak across a row of one hundred squares and then selected which square they thought shone the brightest. The trick was that the brightest square was always near the middle of the row, but the financial incentive was skewed. Participants earned more money for choosing squares farther to the right, with the farthest-right square netting them about $1.30. That may not sound like much, but it was enough to create real tension between doing what was right and doing what was rewarding. In the initial phase, before any social influence was introduced, the researchers found that dedicated rule followers—people who consistently chose the actual brightest square—and committed rule breakers, who always went for the furthest-right square, existed in roughly equal numbers. Each group made up about a fifth of the participants, while the rest fell somewhere in between. The stage was set for something far more interesting: what happens when people are influenced by what others like them have done?
The researchers then stirred the pot, introducing a social element to the experiment. Participants repeated the task several times, but now they were given information about a previous respondent, including that person’s political affiliation and how closely they had stuck to the rule. The results were striking, and a little unsettling. Learning that a previous participant had followed the rules did almost nothing to inspire others to follow them—even when that previous participant shared the same political party. Rule followers, it seems, are not particularly contagious. They quietly do their thing, and no one really notices or cares. Rule breakers, however, were a completely different story. When participants learned that someone with the same political leanings had simply ignored the rule and grabbed the highest payout, their own choices shifted dramatically to the right. Without any social cues, participants chose the farthest-right square about 23 percent of the time. But after learning that a political comrade had made the most lucrative choice, that number jumped to nearly 40 percent. In other words, bad behavior was contagious. It didn’t take a lot to push people toward bending their own moral standards—just a signal that someone on their own team had already done it.
What makes this even more concerning is that most people didn’t just match the rule-breaking level of their predecessors; a small but dangerous subset escalated it. The researchers found that while the majority of individuals’ rule-breaking levels mirrored or stayed below what they observed in others, just over 4 percent of participants went further than the person they were following. They didn’t just break the rules—they pushed the boundaries further, choosing even more extreme deviations from the norm. To understand what this might mean over time and across a larger population, the researchers created a computer simulation. They built a digital twin for each of the 750 participants and let these doppelgängers interact in groups of one hundred. In some simulations, those few escalation-prone individuals were enough to send the entire group spiraling toward wild rule breaking. A small handful of bad actors, it seems, could set off a cascade of deviance that pulled nearly everyone along with them. But there was a catch. If the group of one hundred digital twins contained the same proportion of dedicated rule followers as the human experiment did, the overall level of deviance settled at a more intermediate level. In other words, the quiet, unglamorous presence of people who just follow the rules can serve as a kind of brake, even when a few maniacs are flooring the accelerator.
Eugen Dimant, a behavioral economist at the University of Pennsylvania who was not involved in the study, offered a thoughtful caveat. He praised the research for offering keen insights into how people might behave in a world without consequences, but he was quick to point out that “that’s not how the world works.” Real life is full of punishments, social disapproval, legal penalties, and the quieter but powerful pressure of social norms. We don’t speed the way our fellow drivers speed when we know a police cruiser is nearby; we don’t cheat when we fear being caught and shamed. Dimant’s own work suggests that to truly understand social contagion and the emergence of mobs—whether on highways, in classrooms, or on city streets—researchers must consider these broader societal forces. Rules don’t exist in a vacuum, and neither do rule-breakers. The law, the eye of the community, the fear of consequences, and the desire to maintain a decent reputation all act as guardrails that typically keep behavior in check. The study’s controlled setting strips those factors away, which is exactly why it can reveal something so raw about human nature, but it also means we should be careful not to overgeneralize. Left fully unchecked, a few bad actors might indeed cause chaos, but in the real world, we rarely leave anything fully unchecked.
For Lucas Molleman, however, the study’s real value lies in what it reveals about individual behavior and the fragile mechanics of group dynamics. This pared-down experiment, stripped of the complexities of real life, demonstrates with uncomfortable clarity how just a few bad actors can cause entire groups to spiral out of control. That fundamental insight has enormous implications, from collective speeding on highways to peaceful protests that suddenly turn violent. It’s a deeply human story: we look to others for cues about what is acceptable, and once the envelope is pushed even a little, it becomes easier for everyone else to push it further. We are social creatures, wired to follow the flock, even when the flock is heading off a cliff. The study doesn’t offer easy answers, nor does it pretend to capture all the messy realities of human society. Molleman himself acknowledges this, saying, “This is fundamental science… Obviously reality is way more complex.” But that complexity is exactly why studies like this matter. By understanding the simple, raw instincts that underpin our social behavior, we can begin to understand the more complicated moments when a whole group loses its collective head—and perhaps learn how to hold the line just a little longer the next time the left-lane speeders come roaring past.
