Washington, March 19 : Using brain imaging, scientists have shown that we easily bond with people we consider similar to ourselves.
Adrianna Jenkins, a graduate student in the Department of Psychology in the Faculty of Arts and Sciences at Harvard University and colleagues used fMRI scanning, and found that the region of the brain linked to introspective thought is also accessed when inferring the thoughts of other people who are similar to oneself.
However, they also demonstrated that this is not the case when considering those who are different politically, socially, or religiously, thus possibly explaining why divisions are hard to overcome.
"Our research helps to explain how and when people draw on their own inner experiences to make inferences about the experiences of others. The findings suggest that the part of the brain that is responsible for introspection also helps us to understand what other people might be thinking or feeling. But this primarily seems to be the case for people who we perceive to be similar to ourselves," Jenkins said.
Earlier research revealed that the lower portion of a brain region called the "medial prefrontal cortex" (MPFC) is active when people consider themselves or people like them, and the upper portion of the MPFC indicates judgments about different people. Psychopaths, who have little empathy, have faulty MPFCs.
The Harvard team reports that the same brain region is engaged both when we are introspective about ourselves and when we make inferences about the minds of others who have leanings perceived to be similar to our own.
Jenkins and colleagues tested whether individuals are more likely to access this self-referential region of the brain when considering the thoughts of a similar person or someone who is different. They used fMRI scans to examine brain activity when individuals were asked about their thoughts or feelings regarding an everyday experience, and what they imagine that another person might think or feel about a similar everyday experience.
The study involved 13 students, both graduate and undergraduate, from colleges and universities in the Boston area, who identified themselves as politically liberal at the end of the study.
At the beginning of the study, the subjects were shown photographs of two unfamiliar individuals, and then read a brief descriptive paragraph about each. One individual was described as a student at a college in the Northeast, with liberal political and social attitudes, and one as a conservative, fundamentalist Christian at a large university in the Midwest.
The students were then asked a series of questions about their own thoughts or feelings, and the thoughts or feelings of the liberal or conservative individual. The questions pertained to everyday experiences such as, "How much do you enjoy doing crossword puzzles?" or, "How likely is it that he would get frustrated while sitting in traffic?"
By examining the brain's activity in the vMPFC, the researchers were able to see that the individuals used a similar thought process when considering their own reactions to the questions, and the reactions of the individual that was identified as a liberal college student in the Northeast.
However, the researchers did not see similar activity in this region of the brain when the subjects were considering the thoughts and preferences of the conservative, Midwestern students.
According to Jenkins, it's possible that we rely on our own perspective to assess the potential thoughts and feelings of people who we think are similar, while we may make inferences regarding the thoughts of dissimilar others based on a different process.
The study is published in the current edition of the Proceedings of the National Academy of Sciences.