When was your last Aha! moment? The other day I referred to an “Aha! moment,” which depending on the context can also be called a Eureka Moment, a flash of insight, or even a brainstorm. Writing about it reminded me of a class I took in college called Insight in the Brain, where we studied the psychology of Aha/Eureka Moments, and the contrasts between “incremental” and “intuitive” problem solving.

Incremental problem-solving is long division, or checking every drawer until you find that sock. Insight problems are different. They usually can’t be solved little by little, by process of elimination, or with brute force. With insight problems, you’re sitting there with no answer and no progress, and then a solution comes to you, all at once, as if out of thin air. This can happen with hard problems that you’ve looked at from every angle but haven’t figured out; or with easy problems that require little effort. Either way, the answer comes suddenly, in a flash. If you know the problem space well, you may have an intuitive sense that there is a solution before you solve it; you just don’t see it yet.

In that class we learned the characteristics of insight problems, and the conditions under which insights usually occur. We also learned a clever way of studying them, a type of puzzled called a compound-remote-associates problem, where a subject is presented with three “problem words” and asked to find one “solution word.” For example, a problem triad could be crab / pine / sauce, and the solution could be apple (“crab apple,” “pineapple,” “applesauce”). Solutions to these problems tend to come all at once rather than incrementally or through trial and error, so they are good proxies for insight problems. And because they are easy to write and quick to solve, compound-remote-associates are convenient for testing various conditions under which insight can be boosted or blocked.

So how can we promote insight? First, do all the things you’d expect: get good sleep, hydrate, eat healthy foods, reduce stress, be in a good mood, etc. But for me the most important lesson from this class was simply to embrace subconscious processing. Give your subconscious some time and space to work.

Next time you have some problem you can’t quite crack, step away and think about something else. Or sleep on it for one or more nights. It really does work. Revisit the problem when and how you feel like it. Otherwise, relax and occupy yourself with other things. Eventually, the answer will hit you like a jolt from nowhere. It may happen on a walk, in a dream, or in the shower. Or even more poetically, in the bath, like the canonical (and still most famous) Eureka moment.

Ever since taking this class, I’ve been a huge proponent of allowing the subconscious to do its thing. Whatever the question, I am always encouraging people to “sleep on it.” And I mean literally. I sleep on things all the time. Most of the time I wake up with an answer. Even better, it feels like the solution has come “for free,” with none of the mental effort that would come with consciously working to an answer. There is no strain, it’s just there.

Try it out. Maybe you’ll engineer your own Aha! moment.