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Not surprisingly, a new poll suggesting that Americans think Obama is the worst president since World War II is getting a fair amount of attention, particularly among gleeful conservatives. Thirty-three percent of the respondents, who were offered a list of the 12 U.S. presidents since the war, picked Obama. George W. Bush wasn’t far behind, at 28 percent.

In addition to the obvious reason not to take this too seriously — the predictably sharp partisan divide in how people answered, which leads to the unsurprising conclusion that Republicans don’t particularly care for Obama — there’s another, slightly nerdier one: the availability heuristic.

That sounds fancy, but it simply means that we are biased by how easy it is to summon an example of something in our heads. So when a right-leaning person is asked to think of a bad president, the shadow of Obama looms large over them. To a certain extent, many people who picked Obama weren’t carefully weighing how they viewed him versus other presidents — do you remember how crazy Bill Clinton drove conservatives? — but were swayed by how quickly and loudly Barry O seized their brains once the question was asked.

A few Democratic presidents from now, their anger will be distributed differently, with more of it going toward more recent, salient presidents. (In all of this, of course, the same goes for liberals — W was the only Republican president since his father left office more than two decades ago, so it’s no wonder he topped the list among Democrats.)

Now, surely some of the respondents can build erudite-sounding cases for their choices, and obviously Obama’s presidency has been a bruising one, popularity-wise. But a long-standing finding of political science is that because people don’t follow politics that closely (not owing to any failing on their part — they’re busy!), they often rely on cognitive shortcuts rather than informed opinions when voting of answering polling questions.

That can partly explain how Americans, who apparently think Obama is the worst president in 70 years or so, reelected him a year and a half ago.