Helpful thought: medical lab technicians don't know if they have poor skills.
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The average American probably believes all these statements, according to David Dunning, a professor of psychology at Cornell University. Dunning asks subjects to estimate their abilities in English grammar, logic and humor, and finds that Americans are surprisingly bad at estimating their own skills, knowledge and experience.

And each time, the most inaccurate estimates came from the most inept people.

The biggest idiots, in other words, have a great deal of self-esteem, just as the self-help treatises in popular magazines would have it. "In the United States, you are supposed have high self esteem, supposed to be in control, it's deemed pathological if that's not the self-image you have," says Dunning.

But he thinks exaggerating abilities may be harmful or helpful, depending on the situation. "Everybody is wildly overoptimistic about their ability to pull off a successful marriage. Most marriages fail, but people don't say, 'Yeah, I'm going to make a go of it, but it probably won't work.'" Because of unbridled optimism, "a lot of people get married, and there are demonstrable benefits to that."

Blue line indicates subjects' assessment of their problem-solving ability. Red line indicates performance on a test of problem-solving. Self-assessments of ability had essentially nothing to do with actual ability.
Data from "Assessing..." in the bibliography.

But overestimating your abilities can be dangerous. A recent study of medical lab technicians found the familiar pattern of inaccuracy on the ability to solve problems, and knowledge of laboratory tests and medical lingo. "In all three areas of objective testing, those employees in the bottom percentiles judged their performance as average or even above average compared with coworkers," the researchers wrote (see "Assessing..." in the bibliography).

To Dunning, it just proves the old adage: A little knowledge is a dangerous thing. "It suggests that as you gain experience, you gain explanatory power, you come up with stories that explain events in the world."

Medical menace?
And this, Dunning says, is where we return to our April Fool's theme. If you think you're doing a good job, you won't check your work, so how will you know you're bungling?

It reminds us of the story of "Batesian" mimicry -- the viceroy butterflies that supposedly evolved to resemble toxic monarchs. Dunning says he was surprised anybody bothered checking whether viceroy butterflies might be toxic. "Once something is explained, you don't feel the need to test it anymore. If you have a story, it's already settled, why bother testing it?"

Mythical bibliography? No, way. It's real.