Two neuroimaging studies using functional magnetic resonance imaging and electroencephalography have shown that people with similar personalities tend to have similar brain responses when viewing naturalistic stimuli. This effect was stronger than that of similarity in gender, ethnicity or political affiliation. The study was published in Nature Science Reports.
Each person perceives the world around him in his own way. One person might be inspired by looking at a work of art, another wouldn’t even notice it. One person might enjoy participating in an activity, another would see it as a chore.
Researchers explored the roots of these alignments at the neurological level and found that shared experiences, close relationships, but also gender and cognitive styles affect whether or not two people’s experiences align. People also tend to synchronize their brain activities during social interactions. This happens passively when neural activity is evoked by a common stimulus (something that triggers our senses). But is this passive neural synchronization related to personality traits?
“Given the growing polarization of our world these days, being able to understand how to see the world from someone else’s perspective seems like a key thing. Our interest was in understanding what enables such alignment at different levels: from behavioral and psychological to systemic and neural,” said study authors Sandra Matz of Columbia Business School and Moran Cerf of Northwestern University.
The researchers designed two neuroimaging studies to answer this question. The goal of their first study was to examine the relationship between personality traits and the timing of brain activities using functional magnetic resonance imaging (fMRI). They asked 66 college students to watch an hour-long series of 14 short videos spanning a wide range of genres while undergoing fMRI brain imaging. The students’ basic personality traits were assessed using the Ten-Item-Personality-Inventory (TIPI).
The aim of Study 2 was to test whether the results of Study 1 can be obtained using whole-brain electroencephalography (EEG), but also to examine the roles of an additional set of personality traits narrower (personality sub-facets) in brain response similarity. , to investigate the underlying perceptual mechanisms using eye tracking and to determine whether similarities in political ideology, gender, or ethnicity were related to the level of neural synchronization.
The 303 participants in this study viewed a set of 104 static images on various topics. These participants completed a more comprehensive personality inventory (Big Five Inventory -2, BFI-2) than in the previous study and an eye-tracker recorded their gaze while viewing the images.
Study 1 showed that greater similarity in brain responses to watching videos was linked to higher similarities in personality. This finding applies to a number of used neuronal activity indicators and to different parts of the brain. Higher personality similarity was again associated with higher brain response similarity in Study 2, although participants watched pictures instead of videos.
This effect remained even after controlling for similarity in gender, ethnicity, age, and political ideology.
“The easiest way to sum up the work is that we learned that the way individuals see the world is driven more by their personality than by other dimensions (i.e. gender, race, age, political ideology, etc.),” Matz and Cerf told PsyPost. .
“That is, two people who have similar personalities (i.e. they are both neurotic and agreeable) are much more alike in the way they process incoming stimuli than two people of the same gender, age, race, etc. A 50-year-old Republican black man is more like (in how you process incoming natural stimuli) a pleasant 24-year-old Democratic Asian woman than another unpleasant Republican black man 50 years old.
“We investigate the underlying neural circuitry driving this effect and show that this similarity is the result of internal content appraisal and not simple focus/attention on different aspects of the incoming stimulus,” the researchers explained. .
The same was true when narrower personality traits (personality sub-facets) were considered, with the exception of the sub-facet called aesthetics (facet of Openness to experience personality trait). Gaze similarity was not associated with personality similarity or neural response similarity.
“The fact that personality is so much stronger than other characteristics in driving similarity is quite striking,” Matz and Cerf said. “The intuition would have been that people are more alike based on political ideology or race than personality, because identity politics as well as race, gender or age group (i.e. say, Millennials vs. Baby Boomers) are constantly salient in the media and make dividing by these groups seem critical.Learning that personality could overwhelm these segmentation variables is quite unexpected.
The study highlighted an important link between personality and brain activity. However, the researchers note that their “work did not directly test the hypothesis that personality similarity is related to neural synchrony via shared interpretation of stimuli”, but only inferred it indirectly. The study also did not investigate the behavioral consequences of neural synchrony and this should be addressed in future studies.
“The study was tested on a specific set of somewhat natural stimuli (still images of relatively low emotional valence),” the researchers said. “It is possible/probable that certain content amplifies identity traits (race, gender, political ideology) to a higher level than personality. For example, showing more emotional videos and targeting the very concepts of, say, racial identity, is likely to increase the magnitude of this dimension.
“We believe these types of stimuli make up the majority of the content we engage with lately (both in mainstream media and on social media) and therefore amplify the division into parameter-based echo chambers. identity rather than psychological. We haven’t tested this, but we think it’s a great interesting question.
Additionally, Matz and Cerf – the authors of “said that it would be ‘very interesting to see how these neural similarities and alignments are formed.’
It would also be “useful to see if we can use the content to ‘decode’ personality, using only neural signals,” they added. “That is, put a headset on a person, show them the content and see if – simply by the level of alignment of their brain with other people – you can diagnose some of their psychological properties. .”
“All of these ideas are open questions that haven’t been addressed, but could be a critical next step to really explaining some of the underlying aspects of the work that are still unexplored,” Matz and Cerf said.
The study, “Personality Similarity Predicts Synchronous Neural Responses in fMRI and EEG Data,” was authored by Sandra C. Matz, Ryan Hyon, Elisa C. Baek, Carolyn Parkinson, and Moran Cerf.