With the explosion of news sources over the past two decades, you might think Americans would have greater knowledge about national and international affairs. Not so, says the Pew Research Center, which asked a representative sample of adults a series of nine questions about public figures and news events, which were either identical or comparable to questions asked in surveys conducted in the late ‘80s and early ‘90s.

According to the study, “changing news formats are not having a great deal of impact on how much the public knows.” While how much people know does correlate to how avidly they consume news, Pew found “no clear connection between news formats and what audiences know.” Well-informed Americans are likely to watch The Daily Show, The O’Reilly Factor or NewsHour with Jim Lehrer, listen to NPR or Rush Limbaugh, and look at major newspaper Web sites. Similarly, less-informed audiences also use a mix of news formats, including network morning news shows, local TV news, Fox News Channel and online news blogs.

Other results from the survey include:

• While college graduates still know more than Americans with less education, “scores declined significantly among college graduates, those with some college, as well as for those with a high school education or less,” since 1989.

• People who know more about politics and world events also tend to correctly identify popular celebrities. For example, nearly 80 percent of respondents in the high-knowledge group could identify football star Peyton Manning, compared with only 45 percent of low-knowledge respondents. The same pattern was also found with singer/actress Beyonce Knowles.

• Young people (18-29) know the least, while 50-64 year-olds know the most.

• People who use more news sources know more than those who use fewer sources. About half of the respondents who regularly use at least seven news sources scored in the high-knowledge group by answering correctly an average of 18 questions out of 23,

• Internet news sources, National Public Radio, news magazines and Rush Limbaugh have the best educated audiences; the Internet sources and comedy news shows like The Daily Show and The Colbert Report have younger audiences; the audience for morning network news shows is heavily female, and Limbaugh heavily male, with greater-than-average numbers of men also frequenting major newspaper Web sites, comedy news, O’Reilly, news magazines, and TV news Web sites; conservatives and Republicans favor Limbaugh the most, while more Democrats make up the audience for NewsHour, the comedy news shows, news magazines and major newspaper Web sites.

For a complete list of the questions, go here.