Lazarsfeld's debunking of these models of communication provided the way for new ideas regarding the media's effects on the public. Lazarsfeld introduced the idea of the two-step flow of communication in 1944. Elihu Katz contributed to the model in 1955 through studies and publications. The model of the two-step flow of communication assumes that ideas flow from the mass media to opinion leaders and then to the greater public. They believed the message of the media to be transferred to the masses via this opinion leadership. Opinion leaders are categorized as individuals with the best understanding of media content and the most accessibility to the media as well. These leaders essentially take in the media's information, and explain and spread the media's messages to others.