Abstract
Studying sustained anxiety requires tracing how unpleasant arousal develops, persists and subsides over an unfolding experience. We characterised a 13.5-min first-person film of people undertaking dangerous activities at height as an induction for this purpose. Using an open-source browser-based platform developed for this study, online participants continuously rated their own valence and arousal and completed the somatic subscale of the State-Trait Inventory for Cognitive and Somatic Anxiety before and after viewing. In the confirmatory sample (N = 124), arousal was elevated during the film's rising and sustained phases and declined towards the end, while valence was more unpleasant during the sustained phase than during the opening. Group-mean trajectories closely reproduced the temporal shape observed in an exploratory sample (n = 21; arousal r = .99; valence r = .94). Somatic anxiety increased after viewing (dz = 1.03). Participants reporting larger increases rated the film as more arousing (ρ = .24) and more unpleasant (ρ = −.38). The open-source platform and reference trajectories provide a reusable resource for studying the temporal course of affect during a sustained anxiety induction.