Why is it that sometimes the light between the ears flashes brightly, providing that insightful "aha!" moment of discovery, and sometimes it doesn't come on at all?
Why can we be creative one moment, and dull as a fencepost the next? Scientists have sought the answers to questions like those for centuries, because human creativity is as mysterious as it is important.
But a few answers have trickled in, along with a lot more questions, and experts are beginning to get a grasp on what it is that makes us creative. They're even trying to figure out if there is anything we can do to enhance it.
The latest research shows that "aha" moments come more easily to the mind that is prepared to be creative, even before presented with a problem.
Cognitive scientists at Drexel and Northwestern Universities have been studying creativity for years now, trying to sort out why we are sometimes creative, reaching a conclusion in a flash of light, and why we are sometimes methodical, plodding along until we finally put all the pieces together.
Putting aside the fact that some people are obviously more creative than others, we all approach problems two ways -- sometimes analytically and sometimes waiting for that "aha" moment.
So John Kounios of Drexel, and Mark Jung-Beeman of Northwestern, along with a team of researchers have been looking inside the noggins of volunteers to see if there's any difference in how their brains are working just before an "aha" moment, and just before a bit of plodding. And the results suggest there certainly is a difference.
"If you are going to solve a problem with insight (creativity), there's a characteristic pattern of brain activity even before the problem is presented," says Kounios, a professor of psychology at Drexel. "When it's going to be solved by a more methodical, analytical approach, there's a separate characteristic of brain activity that is different.
"That suggests that a person's brain state, or frame of mind, determines which strategy he or she is going to use to solve a problem when it finally does appear."
The researchers, who are publishing their latest findings in a forthcoming issue of Psychological Science, have used two brain-scanning techniques -- electroencephalograms (EEG) and functional magnetic resonance imaging -- to study the brains of people who were presented with a series of problems.
Some of the problems were best solved methodically, but some were more suited to insightful, creative solutions. Some, of course, could go either way.
The problems included puzzles consisting of three words -- such as tank, hill, secret -- and each participant was asked to think of a single word that could form a compound or common phrase with each of the three words.
Some came up with the right word in a flash -- a true "aha" moment. Others tried many words as they searched methodically for the right one, which is top (tank top, hilltop, top secret).
The brain scans revealed that insightful thinking was marked by increased brain activity in temporal lobe areas associated with conceptual processing, and with frontal lobe areas associated with cognitive control. The methodical approach involved increased activity in the visual cortex at the back of the brain.
Since those conditions showed up before the problem was even presented, the researchers concluded that it is likely that the human brain may be pre-programmed to be either creative or analytical at any given moment.
But if that's so, is there anything we can do to make our brains more creative, or more methodical?
Kounios says their research doesn't completely answer that, but "we have some good reason to believe that some of these aspects are under a person's control."
The work "suggests," he adds, that such things as cognitive exercises, like yoga, might help make a person more creative, since they direct the attention inward, which appears to be tightly linked to creativity. But much more research is necessary to fully answer that, he says.
But how much tinkering do we want to do with the human brain? Kounios points out that some problems are better solved with methodical, analytical reasoning, and some lend themselves better to waiting for the "aha" moment.
"If you are balancing your checkbook, you don't want to be creative," he says. "You want to be methodical and analytical."
So sometimes, it isn't desirable to be creative.
"You don't want a surgeon who improvises," Kounios says. "You want a surgeon who operates according to established procedures that are known to work."
Creativity can sometimes be a bit of a drag, he points out, because "people who tend to be creative tend not to be very focused on their day-to-day business. Their attention seems to be more diffused, spread out. And they tend to be easily distracted.
"People who are more analytical seem to have more focused attention," he says.
But those "aha" moments can be a blast, even if they come rarely.
One of the first characters to recognize that was Archimedes, who is said to have shouted "Eureka" just as he stepped into his bath. Not because the water was too cold, but because he had suddenly solved a problem that he really needed to solve.
Archimedes had been ordered to find out if his king's crown was really pure gold. As he stepped into the tub, so the legend goes, he noticed the water rising as it was displaced by his foot. "Aha," he undoubtedly thought, water displacement could be used to calculate density.
Thus in a flash he solved a problem that more methodical types might not have been able to resolve.
By the way, neither the creative types, nor the methodical types, scored better in the Drexel-Northwestern project.
"For certain types of problems it's likely that using an insight strategy may give you an advantage," Kounios says. "For other types of problems, using an analytical method may be beneficial."
So Archimedes, if you're reading this, don't feel too smug.