A new study suggests that people with compulsive traits—commonly associated with conditions such as obsessive-compulsive disorder (OCD), addiction and eating disorders—may rely on repetitive habits not because they cannot plan ahead, but because they feel uncertain about how their decisions will affect the future.
Researchers from King’s College London found that individuals who show stronger compulsive tendencies are more likely to fall back on habitual behaviours when faced with uncertainty about long-term outcomes. The findings provide a clearer explanation for why repetitive patterns of behaviour are so common in compulsive disorders.
The study involved about 2,000 participants who played an online video game designed to measure decision-making strategies. By analysing players’ choices through mathematical models, scientists were able to distinguish between two different types of decision-making: habit-driven and planning-based.
In behavioural science, habit-driven decisions—known as “model-free” choices—are automatic and rely on past experiences rather than deliberate planning. Planning-based decisions, called “model-based,” require people to mentally simulate future outcomes and choose actions that best support long-term goals.
The research found that people with higher levels of compulsive traits were more likely to rely on the habit-based approach. At the same time, they showed greater uncertainty when trying to predict the long-term consequences of their actions, which appeared to push them toward simpler, repetitive behaviours.
“We found that people with more compulsive traits may rely on habits not because they can’t plan, but because they feel less certain about how their actions will play out,” said Sirichat Sookud, the study’s first author. “This gives us a more precise mechanistic explanation for patterns that have been observed for years.”
Compulsive traits are not limited to clinical disorders. According to the researchers, they exist on a spectrum across the general population, meaning many people without a psychiatric diagnosis may still show mild forms of repetitive behaviour.
The study highlights how everyday decisions often involve a choice between habit and long-term planning. For example, someone trying to improve their health might plan to prepare a nutritious meal after work. Yet they may end up choosing a frozen pizza instead—a quick, familiar option that requires little thought about future consequences.
“Goal-directed decisions depend on having an internal model of how your actions affect future outcomes,” explained Dr Toby Wise, a senior research fellow in neuroscience at King’s College London. “If you want to eat healthier, you need to weigh different options and mentally simulate how each choice affects your long-term health.”
Habit-based decisions, on the other hand, require little or no forward planning. They often emerge from behaviours that previously reduced discomfort or produced a reward, making them more likely to be repeated.
Previous research has already linked a reduced reliance on goal-directed decision-making to psychiatric conditions such as OCD and addiction. In such cases, habitual behaviours—like repeatedly checking whether a door is locked—may develop because they once helped relieve anxiety, eventually becoming automatic.
The new findings suggest that uncertainty about future outcomes may be a key factor pushing people toward these habits.
“If you’re uncertain about what the future may hold, you’re more likely to choose something you’ve done before,” Wise said. “Our data show that people who are more compulsive feel more uncertain about the future, which may explain why they shy away from planning strategies.”
To explore this process, the researchers used a video game based on a well-known psychological experiment called the “two-step task.” The game required players to shoot aliens using a cannon that fired pink or purple balls stored in two containers.
Players needed to learn how the colours of the balls were distributed in each container and also account for uncertainty—some balls could explode before reaching their target. To maximise their success, participants had to combine knowledge about the containers with the probability that each ball might fail mid-flight.
Although the task appears complex, the researchers say it mirrors everyday decision-making, where people constantly weigh probabilities and future outcomes.
Using an online game also allowed the team to recruit a large and diverse sample of participants, generating a rich dataset on human behaviour.
“Online video games like this allow us to measure psychological processes remotely in huge numbers of people,” Wise said. “It opens participation in research to a much wider audience.”
The findings could have implications for future treatments of compulsive behaviours. Rather than focusing solely on breaking habits, therapies might also aim to reduce uncertainty about future outcomes and strengthen people’s confidence in long-term planning.
The research was supported by a Wellcome Trust Career Development Award.
