I've always been fascinated by the failures of genius. Consider Bob Dylan. How did the same songwriter who produced Blood on the Tracks and Blonde on Blonde also conclude that Down in the Groove was worthy of release? Or what about Steve Jobs: What did he possibly see in the hockey puck mouse? How could Bono not realize that Spiderman was a disaster? And why have so many of my favorite novelists produced so many middling works?

The inconsistency of genius is a consistent theme of creativity: Even those blessed with ridiculous talent still produce works of startling mediocrity. (The Beatles are the exception that proves the rule, although their subsequent solo careers prove that even Lennon and McCartney were fallible artists.) The larger point is that mere imagination is not enough, for even those with prodigious gifts must still be able to sort their best from their worst, sifting through the clutter to find what's actually worthwhile.

Nietzsche stressed this point. As he observed in his 1878 book Human, All Too Human:

Artists have a vested interest in our believing in the flash of revelation, the so-called inspiration ... shining down from heavens as a ray of grace. In reality, the imagination of the good artist or thinker produces continuously good, mediocre or bad things, but his judgment, trained and sharpened to a fine point, rejects, selects, connects.... All great artists and thinkers are great workers, indefatigable not only in inventing, but also in rejecting, sifting, transforming, ordering.

Notice the emphasis on rejection. Nietzsche eloquently describes the importance of not just creating but recognizing the value of what has been created.

But this raises the obvious question: How can we sort our genius from our rubbish? The bookshelves groan with how-to guides for bolstering the powers of the imagination. But how can we become better at self-criticism? How can we get excel at the rejection process? Because nobody wants to release Self-Portrait.

A new study led by Simone Ritter of the Radboud University in the Netherlands sheds some light on this mystery. In the first experiment, 112 university students were given two minutes to come up with creative ideas that might alleviate a mundane problem: improving the experience of waiting in line at a cash register. The subjects were then divided into two groups: Half of them went straight to work, while the others were first instructed to perform an unrelated task for two minutes. (They played a silly little videogame.) The purpose of this delay was to give the unconscious a chance to percolate, to let that subterranean supercomputer invent new concepts for the supermarket queue.

There was no difference between the groups in terms of creative output – both the conscious and unconscious/distracted subjects came up with the same number of new ideas. Although previous studies have found an impressive link between unconscious incubation and the imagination – it really is better to sleep on it – that result was not replicated here, perhaps because two minutes of distraction wasn't long enough. (True creativity takes time.)

Here's where things get interesting. After writing down as many ideas as they could think of, both groups were asked to choose which of their ideas were the most creative. Although there was no difference in idea generation, giving the unconscious a few minutes now proved to be a big advantage, as those who had been distracted were much better at identifying their best ideas. (An independent panel of experts scored all of the ideas.) While those in the conscious condition only picked their most innovative concepts about 20 percent of the time – they confused their genius with their mediocrity – those who had been distracted located their best ideas about 55 percent of the time. In other words, they were twice as good at figuring out which concepts deserved more attention.

How can the rest of us get better at identifiying our best ideas? One key lesson from this research is that distraction and dilettantism come with real benefits, as they give the unconscious a chance to assess its new ideas. This reminds me of a wise piece of advice from Zadie Smith, which she dished out to aspiring novelists:

When you finish your novel, if money is not a desperate priority, if you do not need to sell it at once or be published that very second — put it in a drawer. For as long as you can manage. A year or more is ideal — but even three months will do.... You need a certain head on your shoulders to edit a novel, and it’s not the head of a writer in the thick of it, nor the head of a professional editor who’s read it in twelve different versions.

Smith, in other words, is telling writers to forget about their work, to give the mind some time to weigh the worth of all those words. And that's because we have no idea which ideas are worthwhile, at least at first. So the next time you invent something new, don't immediately file a patent, or hit the "publish" button, or race to share the draft with your editor. Instead, take a few days off: Play a stupid videogame, or go for a long walk, or sleep on it. Unless you take a brief break, you won't be able to accurately assess what you've done.

But waiting isn't the only approach. A few years ago, a team of German researchers gave several dozen subjects a variety of word puzzles known as remote associate problems. The puzzles feature three words (such as "pine," "crab" and "sauce") that share a common compound word. (In this case, the answer is "apple.") Here's the clever part: Only some of these remote associate problems had an actual answer. The rest were impossible. Interestingly, the scientists found that subjects in a positive mood were far better at figuring out which remote associate problems could be solved and which were a waste of effort. In fact, even when they didn't end up finding the solution, those who were happy were much better at figuring out which problems had solutions. As a result, they wasted much less time searching for epiphanies that didn't exist, or chasing down possibilities that didn't pan out.

So yes: Taking a break is important. But make sure you do something that makes you happy, as positive moods make us even better at diagnosing the value of our creative work. After a few relaxing days of vacation, you'll suddenly know which new ideas deserve more time and which need to be abandoned. Because even Bob Dylan wrote a few songs he probably shouldn't have sung.

P.S. For more, check out this excellent Tom Jacobs summary of the research.

Image: Greg Westfall/Flickr