The correct answer to this open question is the following.
The Cold War narrowed postwar popular culture in that by the end of the 1940s, there were people inside the film industry that accused some film workers and producers of having ties with Communists or Communists' ideas. Historian Stephen Whitfield said it undermined challenges to the status quo when the House Un-American Activities Committee exposed Communist infiltration in Hollywood in March 1947. Popular actors of the time voluntarily testified. We are talking about Ronald Reagan and Gary Cooper. Congressman Parmel Thomas was the chairman of the committee.