Using MRI scans from nearly 1,000 Dutch individuals, researchers have demonstrated a link between brain structure and ideological beliefs. However, this connection is not as strong as initially anticipated. Still, the scientists consider it noteworthy that variations in brain anatomy are associated with concepts as nuanced as personal ideologies.
Historically, it has been suggested that the brain structures of conservatives differ from those of progressives. Researchers from the University of Amsterdam (UvA) have utilized MRI imaging of around 1,000 Dutch participants to confirm a correlation between brain structure and ideological views. Nevertheless, the significance of this correlation falls short of expectations. The findings remain intriguing, as they associate brain differences with the abstract notion of ideology.
The notion of a connection between brain structure and ideology stems from a 2011 research study conducted on 90 students from England that indicated such a relationship. The UvA team has now carried out the largest replication study to delve deeper into how ideology is connected to brain structure.
In their research, the team examined the MRI scans of 975 Dutch participants aged between 19 to 26, ensuring a representative sampling from the Dutch population regarding education and political leanings. They correlated these scans with survey responses concerning ideological beliefs. “Ideology can be viewed as a collection of stances on various subjects or as part of one’s identity,” clarifies lead researcher Gijs Schumacher. “One can differentiate between ideological perspectives related to socio-cultural matters, like women’s and LGBTIQ rights, and economic topics such as income disparity.”
The amygdala shows slight enlargement
Similar to the findings in the English study, the research revealed that conservative individuals tend to have a slightly larger amygdala. “It’s fascinating that we observed this same finding in our much broader and more representative sample. Unlike the English group, ours included individuals with more extreme conservative views,” remarks Schumacher.
Interestingly, scientists noted that there was no correlation between political ideology and another brain region, the anterior cingulate cortex, which had shown a connection in the prior study.
A minuscule difference
The observed difference in the amygdala’s size between the two groups was likened to the size of a sesame seed. “On average, the conservative participant’s amygdala measures around 157 sesame seeds, while that of a progressive participant measures about 156 sesame seeds. Although this difference is minimal, it is statistically significant. It indicates a connection between brain structure and ideology to some extent, yet the relationship appears to be very indirect,” explains co-author Steven Scholte. “We initially expected to find no such effect.”
“Yet we do not fully understand the link between amygdala size and conservative views,” adds Diamantis Petropoulos Petalas, who contributed to the study but is now affiliated with The American College of Greece. “The amygdala has primarily been studied concerning fear and threatening scenarios, but it appears to be more responsive to emotions overall and to differing opinions. This could indicate that a larger amygdala may result in individuals reacting more vigorously to information, which might sometimes lead to more conservative political perspectives.”
Complex political landscape
Moreover, the research implies that political ideology is far from being a simple binary classification within the brain. “People often refer to blue (Democratic) and red (Republican) brains in the U.S. context. While this metaphor is appealing, it is inaccurate,” states Schumacher. “We propose that ideology should be regarded as a much more complex concept, highlighting that the interplay between brain structure and ideology is less pronounced than previous studies suggested.”
Furthermore, the nature of ideology is more nuanced than previously thought. For instance, Schumacher points out that participants who voted for the SP, a Dutch political party with radical left economic policies but conservative social values, exhibited a larger amygdala on average than those who identified with more progressive parties. “Consequently, ideology encompasses more than mere socio-cultural identification.”
Additional brain regions
The team expanded their investigation to explore potential links between ideology and other brain regions. Notably, they identified a relationship between the volume of the right fusiform gyrus—an area crucial for facial recognition—and more conservative stances on both social and economic matters. The reasons for this connection warrant further exploration.
