Media messages often reach people second-hand, through friends they trust

Studying how voters in Erie County, Ohio made up their minds during the 1940 US election, Paul Lazarsfeld and colleagues expected radio and newspapers to sway people directly. Instead, ideas often passed through 'opinion leaders' who followed the media closely and then influenced friends, family and co-workers. Their 'two-step flow' model is a forerunner of today's interest in influencers.

— Paul Lazarsfeld, Bernard Berelson and Hazel Gaudet, The People's Choice — 1944
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