People influence each other when they interact to solve problems. Such social influence introduces both benefits (higher average solution quality due to exploitation of existing answers through social learning) and costs (lower maximum solution quality due to a reduction in individual exploration for novel answers) relative to independent problem solving. In contrast to prior work, which has focused on how the presence and network structure of social influence affect performance, here we investigate the effects of time. We show that when social influence is intermittent it provides the benefits of constant social influence without the costs. Human subjects solved the canonical traveling salesperson problem in groups of three, randomized into treatments with constant social influence, intermittent social influence, or no social influence. Groups in the intermittent social-influence treatment found the optimum solution frequently (like groups without influence) but had a high mean performance (like groups with constant influence); they learned from each other, while maintaining a high level of exploration. Solutions improved most on rounds with social influence after a period of separation. We also show that storing subjects’ best solutions so that they could be reloaded and possibly modified in subsequent rounds - a ubiquitous feature of personal productivity software - is simiar to constant social influence: It increases mean performance but decreases exploration.

The rise of fake news highlights the erosion of long-standing institutional bulwarks against misinformation in the internet age. Concern over the problem is global. However, much remains unknown regarding the vulnerabilities of individuals, institutions, and society to manipulations by malicious actors. A new system of safeguards is needed. Bwlow, we discuss extant social and computer  science research regarding belief in fake news and the mechanisms by which it spreads. Fake news has a long history, but we focus on unanswered scientific questions raised by the proliferation of its most recent, politically oriented incarnation. Beyond selected references in the text, suggested further reading can be found in the supplementary materials.

In politics, it’s become conventional wisdom that talking seriously to regular Americans doesn’t really pay off. Numerous studies have found that citizens appear to dig in their heels, resisting information that contradicts their beliefs - if they’re informed enough to have meaningful beliefs in the first place. When politicians talk to voters, the goal is usually to rev up their base, or shift a tiny wedge of the "undecided," rather to genuinely persuade a broad swath of the public. This might be a discouraging view of how politics works, but it’s also seen as realistic. If Americans aren’t persuadable, there’s little sense in members of Congress wasting their time trying to have meaningful conversations about the future of the country. This view is also mostly wrong.

We know a lot about fake news. It’s an old problem. Academics have been studying it - and how to combat it - for decades. In 1925, Harper’s Magazine published "Fake News and the Public," calling it’s spread via new communication technoloies "a source of unprecedented dange." That danger has only increased. Some of the most shared "news stories" from the 2016 U.S. election - such as Hillary Clinton selling weapons to Islamic State or the pope endorsing Donald Trump for president - were simply made up.