Understanding the impact of digital platforms on user behavior presents foundational challenges, including issues related to polarization, misinformation dynamics, and variation in news consumption. Comparative analyses across platforms and over different years can provide critical insights into these phenomena. This study investigates the linguistic characteristics of user comments over 34 years, focusing on their complexity and temporal shifts. Utilizing a dataset of approximately 300 million English comments from eight diverse platforms and topics, we examine the vocabulary size and linguistic richness of user communications and their evolution over time. Our findings reveal consistent patterns of complexity across social media platforms and topics, characterized by a nearly universal reduction in text length, diminished lexical richness, but decreased repetitiveness. Despite these trends, users consistently introduce new words into their comments at a nearly constant rate. This analysis underscores that platforms only partially influence the complexity of user comments. Instead, it reflects a broader, universal pattern of human behaviour, suggesting intrinsic linguistic tendencies of users when interacting online.

翻译：理解数字平台对用户行为的影响面临基础性挑战，包括与极化现象、虚假信息传播动态及新闻消费差异相关的问题。跨平台及跨年度的比较分析能为这些现象提供关键洞见。本研究考察了34年间用户评论的语言特征，重点关注其复杂性与时序变化。通过使用来自八个不同平台和主题的约3亿条英文评论数据集，我们分析了用户交流的词汇量、语言丰富度及其随时间演变的情况。研究结果显示，社交媒体平台和主题间存在一致的复杂性模式，其特征表现为文本长度几乎普遍缩短、词汇丰富度降低，但重复性有所下降。尽管存在这些趋势，用户仍以近乎恒定的速率持续在评论中引入新词汇。本分析表明，平台仅部分影响用户评论的复杂性，这实则反映了更广泛、普适的人类行为模式，暗示了用户在线互动时内在的语言倾向性。