Accounting for Personalization in Personalization Algorithms: YouTube's Treatment of Conspiracy Content

This article investigates under which video watch conditions YouTube's recommender system tends to develop a preference for conspiracy-classified videos. Whereas existing research on so-called filter bubbles and rabbit holes tends to rely on non-personalized recommendations and on standard watch patterns, this study puts personalization and diversified user strategies at the center of its design. 20 authenticated bots have been instructed to watch YouTube content based on four distinct watch strategies. In a baseline strategy, bots watched non-conspiracy videos only. Treatment strategies involved watching conspiracy-classified content, selected based on either non-personalized, partly-personalized, or fully-personalized input. Bots watched a total of 15 videos, and after each video their top 20 homepage recommendations were collected and classified as either conspiracy-related or not. This allowed us to measure the impact of each video watched and of each watch strategy on the proportion of conspiracy-classified content recommended at each step. The same experiment has been reverted, exposing the treatment groups to non-conspiracy videos only, to assess the persistence of this pattern. Our results show that users primed with conspiracy-classified content tend to quickly receive a much larger proportion of conspiracy-classified recommendations. Inverting this pattern proves significantly more difficult than generating it. There are also indications that watch strategies relying on personalized content as input might produce stronger effects. This article contributes evidence to the argument that YouTube's recommendation system is prone to generating strong, potentially pernicious recommendation patterns. Moreover, it contributes a replicable methodology that puts personalization at the center of the stage in the study of content personalization algorithms.