Americans seem to have wildly wrong ideas about who makes up political parties.

When you survey Americans, they estimate that a staggering 38 percent of Republican Party supporters earn more than $250,000 a year.

This is impossible, because only 1.5 percent of Americans live in households that have incomes that high. It's even more off base when you consider that rich people are actually much more likely to be Democrats than Republicans. So overall, the total share of Republicans who earn more than $250,000 a year is quite small.

Conversely, Americans also say they believe that nearly a third of the Democratic Party's supporters are gay or lesbian, and that something like 40 percent are African-American.

Again, this is another wild overestimate, because fewer than 4 percent of Americans identify as gay, lesbian, or transgender, and only about 20 percent of Democrats are African-American.

People misperceive the composition of their own party somewhat less than the composition of the opposite party, which is about what you would expect. But the really important — and somewhat frightening — conclusion of this survey is that these misperceptions get worse, not better, among people who pay more attention to politics.

It's yet another example, in other words, of a case where more information about politics leads to less actual knowledge and simply more familiarity with self-justifying stereotypes.

Highly informed Democrats "know" that Republicans are just a bunch of old, rich, Southern evangelicals, while highly informed Republicans "know" that Democrats are gay, black union members. The banal reality that the median member of both parties is a middle-aged, middle-class heterosexual white person gets obscured not by ignorance but by knowledge.

People wildly misperceive the other party

All this comes from a new study by Douglas J. Ahler and Gaurav Sood, who took the simple measure of asking people to estimate the share of supporters of one party or another who belonged to one group or another.

They then made these neat charts (including 95 percent confidence intervals) to show how wildly wrong everyone is. Here's what people think Democrats look like versus what they really look like:

Independents and Democrats have a pretty similar, albeit inaccurate, picture of what the Democratic Party looks like. Republicans have even more misperceptions, but note that the difference between Republicans' perceptions and Democrats' perceptions is small compared with the gap between Democrats' perceptions and reality.

Here's how it looks for Republicans:

Most of these are not quite as wildly off base as they were for the Democratic side, if only because old people, Southerners, and evangelicals are genuinely large groups of people in the US.

But when it came to the one stereotypically Republican group that is genuinely small — very rich people — everyone turned out to guess wildly wrong.

The more you know, the more wrong you are

In general, people are wrong about lots of things — especially when you ask them to guess in situations where nothing is at stake.

That's why what's particularly striking here is that the errors get worse among people who say they follow political news more closely.

This shows that the finding isn't simply general ignorance. It's specifically that paying attention to political news "teaches" people more about party stereotypes and leads them to less accurate guesses — increasing their sense of social distance from the opposition.

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