What role does mass media play, as described in the excerpt, in relation to public opinion?

In the struggle for civil rights, the mass media has served as a powerful instrument to reveal both the injustices and the aspirations of our people. It is not merely a collection of channels broadcasting news, but a dynamic force capable of stirring emotions and mobilizing communities. Through television, radio, and the printed word, the truth of our experiences has been transmitted far and wide. However, it must be recognized that media coverage is not uniformly influential and may be subject to various biases. The diverse array of sources and platforms reflects the multifaceted nature of public discourse, even as it sometimes oversimplifies complex realities. Ultimately, the media’s influence is measured by its capacity to frame narratives and direct public attention.

Martin Luther King Jr., A Vision for Justice, 1963