In general, much of this research has documented a tendency for social media groups that actively discuss scientific issues to be made up of somewhat homogenous, segregated, and often polarised communities of interest with limited intersections between groups holding opposing views, and the vast majority of users on any given platform not taking any active role in any of these discussions of science. This is similar to broader dynamics online where communities of interest tend to coalesce, often around perfectly benign shared interests but sometimes around more ambiguous activities and, of course, in some instances, around shared interest in views that are demonstrably false and activities that are potentially harmful (Philips and Milner 2017). Thus, while we consider findings from the United States, these insights are not universally applicable. We therefore pay particular attention to comparative studies that can help capture differences and similarities across various national contexts and the situation in the United Kingdom specifically. Rehm, P., & Reilly, T. (2010). United we stand: Constituency homogeneity and comparative party polarization. Electoral Studies, 29(1), 40–53. Kreiss, D. (2019). From epistemic to identity crisis: Perspectives on the 2016 U.S. presidential election. International Journal of Press/Politics, 24(3), 383–388.

Commentators and analysts typically worry about echo chambers and filter bubbles because they fear they will fuel polarisation, diminish mutual understanding, and ultimately lead to a situation where people are so far apart that they have no common ground – effectively inhabiting different realities. Polarisation can take substantially different forms. The most important forms for the purposes of this review are the following. First, ideological polarisation, which refers to the degree to which people disagree about political issues. Second, affective polarisation, which refers to people’s feelings about the ‘other side’ – those they disagree with on a given issue. Third, news audience polarisation, which refers to the degree to which audiences for news outlets in a given country are generally more politically partisan or politically mixed.To understand why algorithmic selection is consistently found to lead to more diverse news diets, not narrower diets (let alone echo chambers), it is important to remember that the median number of different sources of news that people in the UK use on a weekly basis offline is two, and just one online (Newman et al. 2021). Search engines and social media do not vastly expand this number and it is not the case that people who use these platforms have very diverse and balanced news diets. Rather, they lead people to slightly more, and slightly more diverse, sources of news than what they seek out of their own volition. Jang, S. M. (2013). Seeking congruency or incongruency online? Examining selective exposure to four controversial science issues. Science Communication, 36(2), 143–167. In terms of distribution, algorithmic selection by digital platforms such as search engines and social media that make personalised display decisions for countless users using automated systems might, some fear, generate filter bubbles by reducing the diversity of information people come across, serving them more attitude- consistent news and resulting in less cross-cutting exposure. I enjoyed writing the character of Beverley Cleverley, the romantic novelist who hires a ghost-writer to write her books for her. Beverley has little or no interest in literature but takes herself incredibly seriously. Over more than twenty years of publishing novels, I’ve met so many different writers at literary festivals and it’s easy to tell the difference between those who are real books people and those who just like the idea of being a writer and are more engaged with the attention that comes their way than with the writing itself. To her credit, however, Beverley hates the divisive terms ‘literary fiction’ and ‘popular fiction’. Her books are squarely part of the latter, but she definitely considers herself to be part of the former.

Prior, M. (2013). Media and political polarization. Annual Review of Political Science, 16(1), 101–127. When it comes to media, there is limited research outside the US and this work does not always find the same patterns as those identified in the US but, at least in the specific context of the United States, it seems that exposure to like-minded political content can potentially polarise people or strengthen the attitudes of people with existing partisan attitudes, and that cross-cutting exposure can potentially do the same for political partisans. Digital media and public discussions around science ↑ Webster, J. G., & Ksiazek, T. B. (2012). The dynamics of audience fragmentation: Public attention in an age of digital media. Journal of Communication, 62(1), 39–56. The Cleverley family live a gilded life, little realising how precarious their privilege is, just one tweet away from disaster. George, the patriarch, is a stalwart of television interviewing, a ‘national treasure’ (his words), his wife Beverley, a celebrated novelist (although not as celebrated as she would like), and their children, Nelson, Elizabeth, Achilles, various degrees of catastrophe waiting to happen. What a thing of wonder a mobile phone is. Six ounces of metal, glass and plastic, fashioned into a sleek, shiny, precious object. At once, a gateway to other worlds – and a treacherous weapon in the hands of the unwary, the unwitting, the inept.Garrett, R. K., Carnahan, D., & Lynch, E. K. (2013). A turn toward avoidance? Selective exposure to online political information, 2004–2008. Political Behavior, 35(1), 113–134. Much of the existing research is focused on the United States, which is in many ways an extreme outlier among high income democracies, as political elites, the media system, and public opinion is more polarised there than in otherwise similar countries. Scheufele, D. A., & Krause, N. M. (2019). Science audiences, misinformation, and fake news. Proceedings of the National Academy of Sciences, 116(16), 7662.