Since people on the Internet inform themselves about political events and exchange, but at the latest with the advent of personalization algorithms in search engines and the dissemination of social media platforms, the question arises as to how online communication takes place within isolated bubbles. In isolated bubbles, information and communication process along personal preferences and worldviews. It is possible that own positions within the interaction between like-minded individuals and personalized technology can be exacerbated until political extremism (Sunstein, 2017, Taylor et al., 2018).

Research that addresses this issue using a variety of technologies and platforms shows mixed outcomes and suggests that at least certain groups of users are moving within echo chambers in online networks, although this does not seem to be the case for the majority (Myth 2, #NoFilter). Likewise, we know that even offline and before the usage of the Internet and social media, people have been more likely to be in contact with people who are similar regarding their characteristics such as social status, personal background and political preferences (Myth 1). But what are rationales that our social environment is often dominated by like-minded people? In addition to causes that concern the availability of interaction partners, research on homophily addresses two potential processes: On the one hand, the active selection of like-minded individuals and on the other hand the formation of uniformity through mutual influence processes (McPherson, Smith-Lovin, & Cook, 2001).

Basically, we prefer relationships (both romantic and non-romantic) with people who think similarly (Byrne & Wong, 1962, Huber & Malhotra, 2017). In context of online dating, Huber & Malhotra (2017) found that users were more willing to write a potential romantic partner if they shared similar political views. Also, in social media, political agreement seems to be relevant to the selection of contacts (Cargnino, Neubaum, & Winter, 2019, Rainie & Smitih, 2012). In a separate experiment, we found that people are more likely to send friend requests to users who share similar views on a controversial social issue (Cargnino et al., 2019). This selectivity was more distinct for those who held a very strong opinion and its peculiarity also depended on the theme of the controversy. Besides the active selection of like-minded people, the selective unfriending of dissenting contacts in online networks may be a selection behavior that could influence the network’s political composition (Bode, 2016; Skoric, Zhu, & Lin, 2018). Bode (2016) used a representative US sample to show that some social media users removed contacts from their own network because they held a different political opinion or were over-emphasizing politics. Politically very active and ideologically more extreme people, as well as supporters of the US Democrats, seemed more likely to remove contacts than others. Similar results were reported by Skoric and colleagues (2018) with a sample of Chinese people. They also suggested that people with stronger political interests and large networks were more likely to remove contacts due to political differences. At the same time, a higher level of cultural collectivism seemed to have an (albeit minor) effect in the opposite direction – these people were less likely to unfriend people who hold different political opinions. Overall, there are indications that illustrate the active role of the user in politically selective compilation of their own online network. At the same time, it can be observed that political selectivity in contact selection is more pronounced in certain social contexts (“heated discourse”) and in certain user groups that differ in the structure of their networks or individual personality traits from other users.

The composition of communication environments, however, can be determined not only by the selection of interaction partners, but also by mutual interaction. Even classical social psychological work differentiates diverse forms of social influence between individuals (Deutsch & Gerard, 1955). According to this work, individuals base their opinions on given group norms (e.g. a majority opinion), for example because they perceive the majority opinion as more accurate than their own or since they are afraid of being confronted with negative reactions by the group in answer to expressing their minority opinion. Furthermore, political homogeneity could also develop over time in social networks, because individuals adopt or subordinate to a perceived (social, group-based) norm.

The previous mentioned aspect is the basic principle of the spiral of silence theory (Matthes, Knoll, & von Sikorski, 2018, Neubaum & Krämer, 2018, Noelle-Neumann, 1974), which assumes that people do not speak out politically since they fear negative social consequences when having the impression of representing a minority opinion. For example, Neubaum & Krämer (2018) suggest that people are less willing to express a minority opinion on Facebook than in offline contexts, as people fear that they are more likely to become the target of personal attacks. The findings also indicated that users’ concerns may be due to their impression to have minor control over others’ responses. A recent meta-analysis by Matthes and colleagues (2018), which summarized the results of more than 60 individual studies, found that people tend to conceal their opinions on the one hand on matters of personal relevance discussed with strangers and on the other hand during communication with close friends and relatives. Though it turned out that people online and offline similarly are inclined to conceal a minority opinion. As people browse in their online networks, hiding their opinions, or even adjusting them to a (perceived) majority due to fear of social sanctions, this could trigger a process in which publicly-visible opinion distributions are becoming more one-sided and more homogenous. As with the active selection of like-minded people, this could undermine long-term democratic principles of diverse opinions and controversial social exchanges. The role of the processes of selection and interpersonal interactions in the emergence of political homophily in (and outside of) social media, whether one of the mechanisms is dominated, or whether both equally and interactively appear, needs to be elucidated by future research. From the current state of knowledge, both the selective choice of contacts and the mutual influence between users are factors that can shape the composition of social networks (Bello & Rolfe, 2014). In the mentioned report, Taylor and colleagues (2018), along with a variety of relevant experts, conclude that understanding how opinions form in the digital age and what psychological, technological, and structural factors affect them is an essential goal for future research. We can fully agree with this assessment.


Bello, J., & Rolfe, M. (2014). Is influence mightier than selection? Forging agreement in political discussion networks during a campaign. Social Networks36, 134–146.

Bode, L. (2016). Pruning the news feed: Unfriending and unfollowing political content on social media. Research & Politics3(3), 205316801666187.

Byrne, D., & Wong, T. J. (1962). Racial prejudice, interpersonal attraction, and assumed dissimilarity of attitudes. The Journal of Abnormal and Social Psychology65(4), 246–253.

Cargnino, M., Neubaum, G., & Winter, S. (2019). Opinion Congruence as a Motive of Friending in Social Networking Sites. Presented at the Annual conference of the Audience and Reception Studies Division of the German Communication Association (DGPuK), Mainz, 31 January – 2 February 2019, Mainz, Germany.

Deutsch, M., & Gerard, H. B. (1955). A study of normative and informational social influences upon individual judgment. The Journal of Abnormal and Social Psychology51(3), 629–636.

Huber, G. A., & Malhotra, N. (2017). Political Homophily in Social Relationships: Evidence from Online Dating Behavior. The Journal of Politics, 79(1), 269–283.

Matthes, J., Knoll, J., & von Sikorski, C. (2018). The “Spiral of Silence” Revisited: A Meta-Analysis on the Relationship Between Perceptions of Opinion Support and Political Opinion Expression. Communication Research45(1), 3–33.

McPherson, M., Smith-Lovin, L., & Cook, J. M. (2001). Birds of a Feather: Homophily in Social Networks. Annual Review of Sociology27(1), 415–444.

Neubaum, G., & Krämer, N. C. (2018). What Do We Fear? Expected Sanctions for Expressing Minority Opinions in Offline and Online Communication. Communication Research45(2), 139–164.

Noelle-Neumann, E. (1974). The Spiral of Silence a Theory of Public Opinion. Journal of Communication24(2), 43–51.

Rainie, L., & Smitih, A. (2012). Politics on Social Networking Sites. Washington, DC: Pew Research Center.

Skoric, M. M., Zhu, Q., & Lin, J.-H. T. (2018). What Predicts Selective Avoidance on Social Media? A Study of Political Unfriending in Hong Kong and Taiwan. American Behavioral Scientist62(8), 1097–1115.

Sunstein, C. R. (2017). #Republic: divided democracy in the age of social media. Princeton ; Oxford: Princeton University Press.

Taylor, S., Pickering, B., Grace, P., Boniface, M., Bakir, V., boyd,  danah, … Zubiaga, A. (2018). Opinion Forming in the Digital Age.

The content that echo chambers are made of
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