Asymmetric effects of semantic compatibility and structural bridging on content propagation: evidence from community vernacular combinations on social media platforms

The rapid expansion of social media platforms and the fragmentation of interest communities have created new theoretical demands for understanding content propagation. Users routinely combine community-specific semantic vernaculars in their content, yet combination-level propagation patterns remain invisible within single-vernacular frameworks. This study constructs a color vernacular co-occurrence network from ACG-related posts on Xiaohongshu (January 2024 to March 2025) and examines how cognitive hierarchy compatibility and network structural position jointly associate with combination propagation outcomes. Three findings emerge. First, semantic hierarchy compatibility positively associates with propagation synergy: within-level compatible combinations correspond to higher propagation gains and cross-level incompatible combinations correspond to negative synergy. Second, cognitive distance associates with propagation outcomes in a monotonically accelerating declining pattern, which does not support the inverted-U hypothesis, because the cognitive gains from semantic novelty cannot offset the decoding burden that accelerates as hierarchical distance increases. Third, semantic hierarchy and community structure show opposite directional associations: cross-level semantics correspond to a negative association while cross-community bridging corresponds to a positive association, and cognitively compatible cross-community combinations consistently outperform incompatible ones. Maintaining semantic hierarchy compatibility while pursuing structural bridging, and incorporating cognitive compatibility into platform recommendation mechanisms, are productive directions for future research.