Multimedia, engagement, and diffusion in alternative online communities: evidence from Spanish telegram channels

Multimedia content has become increasingly prominent in online communication, yet its role in shaping information diffusion in non-algorithmic platforms remains insufficiently understood. This study investigates how content format relates to message visibility and cross-channel diffusion within Spanish alternative Telegram channels. Using a longitudinal dataset of over 1.7 million messages (2019–2025), we analyze engagement through within-channel performance metrics and propagation through inter-channel forwarding networks. Building on theories of cognitive fluency, heuristic processing, and network-based diffusion, we examine the role of multimedia content in driving visibility and information spread. Our results show that multimedia messages are systematically more likely to achieve above-average visibility and to enter cross-channel diffusion circuits, even when controlling for channel-level heterogeneity. Moreover, multimedia diffusion occurs within denser and more centralized forwarding networks, suggesting that content format is associated with distinct structural pathways of amplification. These findings indicate that, in the absence of algorithmic curation, content format functions as a primary driver of both attention and diffusion. Rather than representing a purely stylistic feature, multimedia emerges as a structural component of information dynamics within alternative Telegram ecosystems.