A growing body of evidence points to critical vulnerabilities of social media, such as the emergence of partisan echo chambers and the viral spread of misinformation. We show that these vulnerabilities are amplified by abusive behaviors associated with so-called ''follow trains'' on Twitter, in which long lists of like-minded accounts are mentioned for others to follow. This leads to the formation of highly dense and hierarchical echo chambers. We present the first systematic analysis of  U.S. political train networks, which involve many thousands of hyper-partisan accounts. These accounts engage in various suspicious behaviors , including some that violate platform policies: we find evidence of  inauthentic automated accounts , artificial inflation of friends and followers, and abnormal content deletion . The networks are also responsible for amplifying toxic content from low-credibility and conspiratorial sources. Platforms may be reluctant to curb this kind of abuse for fear of being accused of political bias. As a result, the political echo chambers manufactured by follow trains grow denser and train accounts accumulate influence; even political leaders occasionally engage with them .
A growing body of evidence points to critical vulnerabilities of social media, such as the emergence of partisan echo chambers and the viral spread of misinformation. We show that these vulnerabilities are amplified by abusive behaviors associated with so-called "follow trains" on Twitter, in which long lists of like-minded accounts are mentioned for others to follow. We present the first systematic analysis of a large U.S. hyper-partisan train network. We observe an artificial inflation of influence: accounts heavily promoted by follow trains profit from a median six-fold increase in daily follower growth. This catalyzes the formation of highly clustered echo chambers, URLanized around a dense core of active accounts. Train accounts also engage in other behaviors that violate platform policies: we find evidence of activity by inauthentic automated accounts and abnormal content deletion , as well as amplification of toxic content from low-credibility and conspiratorial sources. Some train accounts have been active for years, suggesting that platforms need to pay greater attention to this kind of abuse .
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''follow trains''
"follow trains"
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This leads to the formation of highly dense and hierarchical echo chambers.
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a large
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political train networks, which involve many thousands of hyper-partisan accounts. These accounts engage in various suspicious behaviors , including some
hyper-partisan train network. We observe an artificial inflation of influence: accounts heavily promoted by follow trains profit from a median six-fold increase in daily follower growth. This catalyzes the formation of highly clustered echo chambers, URLanized around a dense core of active accounts. Train accounts also engage in other behaviors
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activity by
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, artificial inflation of friends and followers, and
and
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. The networks are also responsible for amplifying
, as well as amplification of
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Platforms may be reluctant to curb
Some train accounts have been active for years, suggesting that platforms need to pay greater attention to
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for fear of being accused of political bias. As a result, the political echo chambers manufactured by follow trains grow denser and train accounts accumulate influence; even political leaders occasionally engage with them