  Worldviews may differ significantly according to political orientation. Even
a single word can have a completely different meaning depending on political
orientation. However, no direct evidence has been obtained on differences in
the semantic processing of single words in naturalistic information between
individuals with different political orientations. The present study aimed to
fill this gap. We measured electroencephalographic signals while participants
with different political orientations listened to naturalistic content.
Responses for moral-, ideology-, and policy-related words between and within
the participant groups were then compared. Within-group comparisons showed that
right-leaning participants reacted more to moral-related words than to
policy-related words, while left-leaning participants reacted more to
policy-related words than to moral-related words. In addition, between-group
comparisons also showed that neural responses for moral-related words were
greater in right-leaning participants than in left-leaning participants and
those for policy-related words were lesser in right-leaning participants than
in neutral participants. There was a significant correlation between the
predicted and self-reported political orientations. In summary, the study found
that people with different political orientations differ in semantic processing
at the level of a single word. These findings have implications for
understanding the mechanisms of political polarization and for making policy
messages more effective.
