The fragility of opinion formation in a complex world.

How does the complexity of the world around us affect the reliability of our opinions? Motivated by this question, we quantitatively study an opinion formation mechanism whereby an uninformed observer gradually forms opinions about a world composed of subjects interrelated by a signed network of mutual trust and distrust. We show numerically and analytically that the observer's resulting opinions are highly inconsistent (they tend to be independent of the observer's initial opinions) and unstable (they exhibit wide stochastic variations). Opinion inconsistency and instability increase with the world's complexity, intended as the number of subjects and their interactions. This increase can be prevented by suitably expanding the observer's initial amount of information. Our findings imply that an individual who initially trusts a few credible information sources may end up trusting the deceptive ones even if only a small number of trust relations exist between the credible and deceptive sources. Identifying potential mechanisms behind opinion formation is key to curb the spread of misinformation and fake news. Here, the authors propose a model of opinion formation on a network of relations of trust and distrust between subjects, and show that opinion instability increases with the complexity and size of the system, proposing a candidate mechanism for how trust towards deceptive sources develops. [ABSTRACT FROM AUTHOR]