Researchers at Brown University found that individuals on the far left and far right may process political content in more similar ways than previous studies have assumed. The findings suggest that extremity, rather than ideological direction, predicts how individuals respond neurologically and physiologically to charged political information.
The study was conducted by cognitive scientists Daantje de Bruin and Oriel FeldmanHall. Both specialize in political psychology, affect, and decision-making. Details of their findings are in a paper published in the August 2025 issue of the peer-reviewed Journal of Personality and Social Psychology by the American Psychological Association.
Participants included 44 adults, divided evenly between self-identified left-leaning individuals and right-leaning individuals. Many of them reported holding strong or extreme views. They were recruited to watch a politically charged video while researchers measured their brain activity, physiological arousal, and eye movements simultaneously.
Specifically, to capture brain responses, the team used functional magnetic resonance imaging. They combined this with galvanic skin response testing to monitor arousal levels and eye tracking to record gaze patterns. The integration of these tools allowed them to compare how moderates and extremists processed the same political content with scientific precision.
The researchers aimed to determine whether ideological direction or degree of extremity shaped neural synchronization, test the influence of how inflammatory versus neutral political language, and investigate whether shared physiological arousal could explain similarities in brain activity among the participants. The following are the main findings:
• Extreme Synchrony: Individuals with extreme political views demonstrated more similar brain activity to each other, regardless of being left-leaning or right-leaning, compared to moderates. This indicates that extremity, not ideology, is the primary driver of neural synchrony in processing political content.
• Key Brain Regions: Extremists had stronger responses in the amygdala, periaqueductal gray, and posterior superior temporal sulcus. These are linked to emotional salience, defensive responses, and social cognition. The posterior superior temporal sulcus showed noticeable heightened synchronization among extremists.
• Language Impact: When exposed to political segments with inflammatory or provocative language, extremists exhibited stronger synchronization of brain activity. These segments magnified the similarity of responses across political extremes, suggesting that emotional rhetoric unifies the way extremists perceive political messages.
• Physiological Arousal: Galvanic skin response tests indicated that extremists experienced similar physiological arousal. This shared arousal reinforced their neural synchronization, demonstrating that heightened emotion operates as a binding factor, aligning how individuals at the extremes process political content.
• Moderate Diversity: Moderates showed diverse and less synchronized responses both neurologically and physiologically. They were less affected by inflammatory language. This suggests that moderates process political messages with greater variability and are less driven by high levels of emotional arousal.
These findings provide scientific support for what is often described as horseshoe theory. Note that this theory proposes that far-left and far-right individuals may resemble each other more in style or form than in substance. Moreover, while beliefs differ, their cognitive and emotional processing patterns under charged conditions appear strikingly aligned.
Several implications were provided. Emotional arousal and inflammatory rhetoric can powerfully shape how extremists perceive political content. This can reinforce polarization and resistance to alternative perspectives. Moderates, in contrast, may be more open to diverse interpretations because their responses are not uniformly driven by heightened affect.
Those at polar opposites may share more in common at the level of cognitive processing. The authors cautioned that the study has limitations. The sample size was relatively small, typical for neuroimaging research, and the content used was specific to U.S. politics. The results are correlational and may not apply universally across cultures or political contexts.
FURTHER READING AND REFERENCE
- De Bruin, D. and FeldmanHall, O. 2025. “Politically Extreme Individuals Exhibit Similar Neural Processing Despite Ideological Differences.” Journal of Personality and Social Psychology. DOI: 1037/pspa0000460