20世纪40年代，勒温在生涯晚期实现了学术转型。远离格式塔心理学后，他转向关注社会治理问题的应用心理学研究，并将场论演绎为更具传播视角的“渠道理论”。基于群体动力学与拓扑心理学，勒温借助二战期间所开展的“饮食习惯研究”，观察群体内部的信息传播与资源流动机制，提炼出“把关人”“门区”“渠道”等一系列关键概念，对后来的新闻生产社会学和传播学产生了深远影响。然而，在怀特等人引介勒温学说的过程中，整体性的“渠道理论”框架遭到忽视，仅有“把关人”这一概念被抽取并凸显，勒温原有理论中关于社会冲突、群体心理与物质性要素的复杂思考则被淡化。加之早期把关研究深受信息论范式的影响，其解释力在一定程度上压制了渠道理论所强调的群体结构路径。随着勒温的早逝，该理论未能得到系统完善与广泛传承，最终成为传播学术史中的“灰色地带”。

In the 1940s, Kurt Lewin underwent an academic transformation in the later stage of his career. Moving away from Gestalt psychology, he shifted his focus toward applied psychology research addressing social governance issues and developed his field theory into the more communication-oriented “channel theory”. Based on group dynamics and topological psychology, Lewin drew on his “food habits study” conducted during World War II to observe mechanisms of information dissemination and resource flow within groups. From this, he derived key concepts such as “gatekeeper”, “gate region” and “channel”, which profoundly influenced later sociological studies of news production and communication research. However, when scholars like White introduced Lewin’s ideas, the holistic framework of “channel theory” was largely overlooked. Only the concept of the “gatekeeper” was extracted and emphasized, while the complex considerations in Lewin’s original theory—such as social conflict, group psychology, and material factors—were diluted. Moreover, early gatekeeping studies were heavily influenced by the information theory paradigm, whose explanatory power somewhat suppressed the group structural perspective emphasized by channel theory. With Lewin’s premature death, the theory was never systematically refined or widely inherited, eventually becoming a “gray area” in the history of communication scholarship.