Why has the number of voters who think President Obama is a Muslim increased? John Sides looks at the data and finds that the increase has come mostly among Republicans with a college degree or some college:
I divide the sample into Democrats and Republicans. Independents who lean toward a party are counted as partisans (see here for why), so this analysis includes about 90 percent of the sample. I then divide the sample into the education categories that Pew provided: those with a high school degree or less, those with some college education, and those with a college degree or more.
The growth in this perception among Democrats is small and is consistent across education levels: a 2-4 increase within each level. By contrast, the growth in this perception among Republicans is more notable among those with some college education (a 19-point increase) or a college degree (15 points) than among those with a high school degree or less (9 points). In other words, better educated Republicans have changed more than the less educated Republicans. This flies in the face of the "dumb Americans" idea and provides some support for Nyhan's hypothesis. The people most likely to hear the "Obama is a Muslim" meme are the ones whose beliefs changed most dramatically in the past 17 months.
Now, why would this be happening? Why would people with higher levels of education be disproportionately embracing a myth?
This actually comports with an established phenomenon in American politics. Partisans are more likely to consume news sources that confirm their ideological beliefs. People with more education are more likely to follow political news. Therefore, people with more education can actually become mis-educated. As Larry Bartels has written:
Voters’ perceptions may be seriously skewed by partisan biases. For example, in a 1988 survey a majority of respondents who described themselves as strong Democrats said that inflation had “gotten worse” over the eight years of the Reagan administration; in fact, it had fallen from 13.5 percent in 1980 to 4.1 percent in 1988. Conversely, a majority of Republicans in a 1996 survey said that the federal budget deficit had increased under Bill Clinton; in fact, the deficit had shrunk from $255 billion to $22 billion. Surprisingly, misperceptions of this sort are often most prevalent among people who should know better—those who are generally well informed about politics, at least as evidenced by their answers to factual questions about political figures, issues, and textbook civics.
Why are Republicans with a college degree or some college embracing the view that Obama is Muslim? They're probably more tuned into right-wing blogs or other sources of alternative news and misinformation.