Collective behaviour in video viewing

Videos and commercials produced for large audiences can elicit mixed opinions. We wondered whether this diversity is also reflected in the way individuals watch the videos. To answer this question, we presented 65 commercials with high production value to 25 individuals while recording their eye movements, and asked them to provide preference ratings for each video. We find that gaze positions for the most popular videos are highly correlated. To explain the correlations of eye movements, we model them as ”interactions” between individuals. A thermodynamic analysis of these interactions shows that they approach a ”critical” point such that any stronger interaction would put all viewers into lock-step and any weaker interaction would fully randomise patterns. At this critical point, groups with similar collective behaviour in viewing patterns emerge while maintaining diversity between groups. Our results suggest that popularity of videos is already evident in the way we look at them, and that we maintain diversity in viewing behaviour even as distinct patterns of groups emerge. Our results can be used to predict popularity of videos and commercials at the population level from the collective behaviour of the eye movements of a few viewers. It is often said that our preferences and biases influence the way we see the world. This is literally true when viewing static images, where prior preferences influence our gaze, and inversely, our point of gaze can affect our subsequent judgments of what we see [1, 2]. Thus, it is conceivable that our differing preexisting preferences are only reinforced by a biased view of the world, even during such simple behaviours as looking at images. On the other hand, viewers seem to have a remarkably similar way of looking at dynamic visual stimuli. Well-produced movies, in particular, effectively synchronize eye-movement trajectories across viewers [3, 4]. Perhaps more importantly, movies elicit quite similar brain responses across viewers [5], especially when the audience is engaged and attentive [6, 7]. Interestingly, this similarity of brain responses can predict various preferences of large audiences [8]. Perhaps then, well-produced video material also synchronises judgments, and so we asked whether similarity of eye movements is predictive of collective preference ratings. To answer this question, we selected videos with high production value that have been viewed by large audiences. We used commercials aired during the 2014 Super Bowl championship game of the National Football League (American football), watched by over one hundred million people [9] and for which population-level preferences ratings are readily available. The quantitative analysis of these data is based on homophily and inter-subject correlation (ISC). In sociology, the study of homophily has gained considerable attention by showing that