A recent study reveals that damage to specific areas of the medial prefrontal cortex not only heightens personal impulsivity but also makes individuals more prone to adopting impulsive behaviors observed in others.
Key Points at a Glance
- Study involved 121 participants, including individuals with focal brain damage.
- Damage to the dorsomedial prefrontal cortex linked to increased susceptibility to others’ impulsive decisions.
- Damage to the ventromedial prefrontal cortex associated with heightened personal impulsivity.
- Findings suggest distinct neural pathways for personal and socially influenced impulsivity.
- Implications for understanding decision-making processes and susceptibility to external influences.
Focal brain damage, particularly to key regions of the medial prefrontal cortex, doesn’t just affect cognitive performance — it alters how we interact with the world socially and emotionally. A groundbreaking new study published in PLOS Biology by researchers from the University of Birmingham, in collaboration with the University of Oxford and Julius-Maximilians-University Würzburg, reveals that individuals with specific prefrontal brain injuries are not only more impulsive themselves, but also more likely to adopt the impulsive behaviors of others.
This research is among the first to demonstrate that distinct areas of the brain regulate how we respond to the impulsivity of people around us. By working with a rare group of patients who have sustained damage to the medial prefrontal cortex (mPFC), scientists were able to pinpoint how lesions in different subregions affect not only self-control, but also social influence.
The study examined 121 participants, including 33 individuals with focal damage to the mPFC, 17 with lesions elsewhere in the brain, and 71 healthy controls. The team presented participants with choices involving smaller, immediate rewards versus larger, delayed rewards — a classic test of impulsivity. After making their decisions, participants were shown the choices of others, allowing researchers to measure how much external behavior swayed their own future choices.
The results were striking. Those with damage to the ventromedial prefrontal cortex (vmPFC) exhibited increased personal impulsivity. That is, they were more likely to choose smaller, immediate rewards over larger, delayed ones — a pattern well-documented in previous research. However, what’s new is how individuals with damage to the dorsomedial prefrontal cortex (dmPFC) responded: they weren’t just impulsive themselves — they were significantly more likely to copy other people’s impulsive behavior.
This shows a clear dissociation in brain function. The vmPFC appears to be a center for internally guided decision-making and future planning, while the dmPFC plays a critical role in regulating social influence. When this latter area is damaged, individuals become more vulnerable to the sway of others — especially those who make rash decisions.
This vulnerability has far-reaching implications. In real-world scenarios, people with dmPFC damage may be more likely to follow peers into risky or ill-considered actions, whether in financial decisions, substance use, or even spreading misinformation. Their internal “filter” for evaluating the quality of others’ choices appears to be impaired, making them social chameleons in the worst possible way.
Lead author Zhilin Su emphasized the significance of the study’s rare participant group: “We were able to work with a large sample of participants with an uncommonly specific damage to the medial prefrontal cortex. This gave us an opportunity to very specifically look at whether this damage might affect how influenced people are by others.”
The team’s ability to distinguish between types of impulsivity — internally generated versus socially induced — is a major advance in neuroscience. As co-author Professor Patricia Lockwood noted, “Our study shows that being influenced by others has a specific neural basis, which could have implications for everything from how we understand misinformation to how other people can change our own financial preferences.”
Understanding these brain mechanisms is crucial for both clinical treatment and broader social awareness. For clinicians, recognizing that patients with dmPFC damage may be especially susceptible to external influence could shape therapeutic interventions — particularly in addiction recovery or post-injury rehabilitation, where social context can significantly affect outcomes.
The findings also carry weight in the digital age. With the constant barrage of online opinions, trends, and misinformation, people with damage to areas like the dmPFC might be at greater risk of manipulation. This neurological vulnerability adds a new layer of complexity to conversations about cognitive bias and digital literacy.
Importantly, this research does not suggest that people with these types of brain injuries are incapable of making rational decisions. Rather, it shows that their cognitive processes may weigh social input more heavily — even unconsciously — than those of neurotypical individuals. By better understanding the neural architecture that supports decision-making, we can begin to build support systems that account for these differences, offering protection and empowerment to those with neurological impairments.
As research in this area progresses, the team hopes to explore whether similar patterns exist in psychiatric conditions that involve altered social cognition, such as borderline personality disorder or schizophrenia. The ability to separate and understand the brain’s systems for self-control and social influence may open up new pathways for diagnostics, therapy, and even preventive care.
Ultimately, the study reaffirms a central truth of modern neuroscience: our brains are not just decision engines — they are deeply social machines. And when certain gears are damaged, it’s not just our own behavior that changes, but the very way we reflect and absorb the behavior of others.
Source: University of Birmingham
