Affect in science communication: A data-driven analysis of TED talks on YouTube

Science communication is evolving as it is increasingly directed at the public rather than at academic peers. Understanding the circumstances under which the public engages with scientific content is therefore crucial to improving science communication. In this article, we investigate the role of affect on audience engagement with a modern form of science communication: TED talks on the social media platform YouTube. We examined how affect valence---a net positive or negative affect---and density---the proportion of affective words---are associated with a talk's popularity---reflecting views and likes---and polarity---reflecting dislikes and comments. We found that the valence of TED talks was associated with both popularity and polarity, with positive valence being linked to higher talk popularity and lower talk polarity. Density, on the other hand, was only associated with popularity, with higher affective density being linked to higher popularity---even more so than valence---but not polarity. Moreover, we observed that the association between affect and engagement was moderated by talk topic, but not whether the talk included scientific content or not. We discuss possible mechanisms and implications of our findings for increasing the effectiveness of science communication.