Fig. 1

The overall procedure of the three-stage user studies. \(S_1\): Participants browsed videos featuring positive or negative polarity on 10 personages. Their behavior signals, brain signals, and explicit responses are collected during the video browsing process or the post-experiment questionnaire. \(S_2\): Participants browsed short videos about these personages posted by the Platform in a field study lasting 6 days. For each personage, the Platform only recommended videos with either positive or negative polarity, which acts as a manifestation of CP. \(S_3\): The last stage resembles the procedures in stage \(S_1\). However, it diverges in the selected videos and the timing of the questionnaire.