From Comments to Cognition: How online comments on social media influence personal opinion

Abstract

Social media has become central in our daily life, serving both as a mean of interpersonal connection and as a primary source of news consumption. This doctoral dissertation investigates the behavioral and neuroimaging effects of online comments written below news headlines posted on social media platforms. We developed a novel behavioral paradigm to address limitations in previous research. This behavioral paradigm was validated using a sample of around 440 individuals from U.S. and Germany. Results indicated that participants consistently updated their opinions in accordance with the sentiment expressed in the comments. The degree of opinion change was significantly greater when participants had both strong pre-existing attitudes toward the topics and when they had high confidence in their initial opinions about the news headlines. Susceptibility to social influence was mitigated by the level of digital maturity. Subsequently, the behavioral task was adapted for fMRI compatibility. In a fMRI study with 41 participants, we corroborated our previous behavioral findings showing participants updating their opinions following the sentiment expressed in the comments. The update was significantly greater both when comments were incongruent with participants’ initial opinions and when their initial opinion was weak. Comment congruence with initial opinions also led to increased opinion polarization. Neuroimaging data revealed activation in the theory of mind network when participants read comments related to the news headlines compared to irrelevant comments. The activation was smaller for comments incongruent with participants’ initial opinions, possibly signifying a motivation not to engage with divergent viewpoints. In conclusion, this doctoral thesis demonstrates the powerful influence of online comments on social media in shaping public opinion on important contemporary issues, with potential implication for societal decision-making.