Abstract
Social media feeds expose users to rapidly changing streams of content, but relatively little is known about how long individual posts remain available for processing during user-controlled scrolling. We analyzed high-resolution behavioural logs from a fully interactive, simulated Instagram-like platform, to characterize dwell time and identify factors associated with variation in exposure duration. Preregistered analyses included 43,921 post-viewing episodes from 1,102 participants. Exposure was typically brief and highly variable, with the median dwell time lasting only 0.93 seconds. Mixed-effects models showed little evidence that visual complexity, valence, arousal, thematic content, presence of a face, social reinforcement, or measured individual characteristics were associated with dwell time. Instead, dwell time declined substantially across the browsing sequence and was considerably longer for posts encountered on profile and explore pages than in the main feed. These findings characterize social media browsing as a sequence of heterogeneous, often momentary exposures and demonstrate the value of simulated platforms for studying scrolling behavior at high temporal resolution.