The Ranking Effect: How Algorithmic Rank Influences Attention on Social Media

Social media feeds have become central to the Internet. Among the most visible are trending feeds, which rank content deemed timely and relevant. To examine how feed signals influence behaviors and perceptions, we conducted a randomized experiment (n = 585) simulating Reddit's r/popular feed. By having participants view identical sets of posts in different orders, we isolate the effects of rank and social proof on engagement and perceived relevance, trustworthiness, and quality. We found that lower-ranked posts received about 40% less engagement, despite participants rarely reporting rank as a factor in their choices. In contrast, neither rank nor social proof shifted perceptions across the three dimensions. We also observed demographic patterns: older participants were more skeptical of trending content, while those with less formal education expressed greater trust. Overall, our findings show that algorithmic curation implicitly steers attention, with implications for platform design, research on algorithmic influence, and policy.