In 1936 Graham Wallas, co-founder of the London School of Economics, published The Art of Thought, outlining the four stages of the creative process. This pre-dates, by at least a decade, James Webb’s A Technique for Producing Ideas.
Wallas’s model “is still the most common explanation of how insight works. If you do any exploration into the field of insight, you can’t go far without bumping into Wallas, who is the epitome of a British freethinking intellectual,” writes Gary Klein in Seeing What Others Don’t: The Remarkable Ways We Gain Insights.
The Creativity Question, published in 1976, preserves Wallas’s “Stages of Control” and presents his model of insight: (1) preparation; (2) incubation; (3) illumination; and (4) verification.
In Seeing What Others Don’t: The Remarkable Ways We Gain Insights, Klein summarizes:
During the preparation stage we investigate a problem, applying ourselves to an analysis that is hard, conscious, systematic, but fruitless.
Then we shift to the incubation stage, in which we stop consciously thinking about the problem and let our unconscious mind take over. Wallas quoted the German physicist Hermann von Helmholtz, who in 1891 at the end of his career offered some reflections on how this incubation stage feels. After working hard on a project, Helmholtz explained that “happy ideas come unexpectedly without effort, like an inspiration. So far as I am concerned, they have never come to me when my mind was fatigued, or when I was at my working table. They came particularly readily during the slow ascent of wooded hills on a sunny day.”
Wallas advised his readers to take this incubation stage seriously. We should seek out mental relaxation and stop thinking about the problem. We should avoid anything that might interfere with the free working of the unconscious mind, such as reading serious materials.
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Next comes the illumination stage, when insight bursts forth with conciseness, suddenness, and immediate certainty. Wallas believed that the insight, the “happy idea,” was the culmination of a train of unconscious associations. These associations had to mature outside of conscious scrutiny until they were ready to surface. Wallas claimed that people could sometimes sense that an insight was brewing in their minds. The insight starts to make its appearance in fringe consciousness, giving people an intimation that the flash of illumination is nearby. At this point the insight might drift away and not evolve into consciousness. Or it might get interrupted by an intrusion that causes it to miscarry. That’s why if people feel this intimation arising while reading, they often stop and gaze out into space, waiting for the insight to appear. Wallas warned of the danger of trying to put the insight into words too quickly, before it was fully formed.
Finally, during the verification stage we test whether the idea is valid. If the insight is about a topic such as mathematics, we may need to consciously work out the details during this final stage.
Wallas noted that none of these stages exist in isolation.
In the daily stream of thought these four different stages constantly overlap each other as we explore different problems. An economist reading a Blue Book, a physiologist watching an experiment, or a business man going through his morning’s letters, may at the same time be “incubating” on a problem which he proposed to himself a few days ago, be accumulating knowledge in “preparation” for a second problem, and be “verifying” his conclusions on a third problem. Even in exploring the same problem, the mind may be unconsciously incubating on one aspect of it, while it is consciously employed in preparing for or verifying another aspect. And it must always be remembered that much very important thinking, done for instance by a poet exploring his own memories, or by a man trying to see clearly his emotional relation to his country or his party, resembles musical composition in that the stages leading to success are not very easily fitted into a “problem and solution” scheme. Yet, even when success in thought means the creation of something felt to be beautiful and true rather than the solution of a prescribed problem, the four stages of Preparation, Incubation, Illumination, and the Verification of the final result can generally be distinguished from each other. (The Creativity Question)
If you talk to anyone about insight today, most people are familiar with the model Wallas proposed.
“It’s a very satisfying explanation that has a ring of plausibility,” writes Klein, “until we examine it more closely.”
Klein points to many counterexamples where people had insights that came unexpectedly, without a preparation stage. A lot of people aren’t wrestling with a problem when they come up with an accidental insight.
According to Wallas, when we’re stuck and need to find an insight that will get us past an impasse, we should start with deliberate preparation. … One flaw in Wallas’s method is that his sample of cases was skewed. He only studied success stories. He didn’t consider all the cases in which people prepared very hard but got nowhere.(Seeing What Others Don’t: The Remarkable Ways We Gain Insights)
Specific preparation doesn’t always lead to insights. And the people who gain insights may or may not follow the Wallas model, so perhaps it is incomplete.
We need another theory.
Discontinuous Discoveries
Sometimes shifts in thinking are not about making minor adjustments or adding details. Sometimes we fundamentally shift core beliefs. This allows us to see the problem in a new way and may lead to insight. We shift from a poor story to a better one. These are discontinuous discoveries.
Insights shift us toward a new story, a new set of beliefs that are more accurate, more comprehensive, and more useful. Our insights transform us in several ways. They change how we understand, act, see, feel, and desire. They change how we understand. They transform our thinking; our new story gives us a different viewpoint. They change how we act. … Insights transform how we see; we look for different things in keeping with our new story. (Seeing What Others Don’t)
In Wolf Hall, Hilary Mantel makes an important observation, “Insight cannot be taken back. You cannot return to the moment you were in before.” After insight, everything is different.
Insights are unique is some other ways:
When they do appear, they are coherent and unambiguous. They don’t come as part of a set of possible answers. When we have the insight, we think, “Oh yes, that’s it.” We feel a sense of closure. This sense of closure produces a feeling of confidence in the insight. (Seeing What Others Don’t)
The Difference Between Insight and Intuition
Intuition is the use of patterns they’ve already learned, whereas insight is the discovery of new patterns. (Seeing What Others Don’t)
The Role of Stories
Stories are a way we frame and organize the details of a situation. There are other types of frames besides stories, such as maps and even organizational wiring diagrams that show where people stand in a hierarchy. … These kinds of stories organize all kinds of details about a situation and depend on a few core beliefs we can call “anchors,” because they are fairly stable and anchor the way we interpret the other details. (Seeing What Others Don’t)
And anchors can change. They change when we get new information. They change when we shift our beliefs.
What causes us to change our story? Klein proposes five strategies connections, coincidences, curiosities, contradictions, and creative desperation.
In all of these cases we change our story.
When faced with creative desperation, we try to find a weak belief that is trapping us. We want to jettison this belief so that we can escape from fixation and from impasse. In contrast, when using a contradiction strategy, we center on the weak belief. We take it seriously instead of explaining it away or trying to jettison it. We use it to rebuild our story. (Seeing What Others Don’t)
When we’re desperate, we’re more likely to attack a weak anchor and give something a try.
In times of desperation, we actively search for an assumption we can reverse. We don’t seek to imagine the implications if the assumption was valid. Rather, we try to improve the situation by eliminating the assumption. (Seeing What Others Don’t)
But changing our story is not the only way to gain insight. We can also add new anchors.
The Triple Path
In the end, Klein came up with the tripe path model of insight, which tries to capture the similarities between the strategies.

The connection path is different from the desperation path or the contradiction path. We’re not attacking or building on weak anchors. When we make connections or notice coincidences or curiosities, we add a new anchor to our beliefs and then work out the implications. Usually the new anchor comes from a new piece of information we receive.
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I’ve combined the connections, coincidences, and curiosities in the Triple Path Model. They have the same dynamic: to build on a new potential anchor. They have the same trigger: our thinking is stimulated when we notice the new anchor. Coincidences and curiosities aren’t insights in themselves; they start us on the path to identifying a new anchor that we connect to the other beliefs we hold. Connections, coincidences, and curiosities have the same activity: to combine the new anchor with others. This path to insight doesn’t force us to abandon other anchors. It lets us build a new story that shifts our understanding. This path has a different motivation, a different trigger, and a different activity from the contradiction and the creative desperation paths. Nevertheless, like the other two paths, the outcome is the same: an unexpected shift in the story.
Each of the three paths, the contradiction path, the connection path, and the creative desperation path, gets sparked in a different way. And each operates in a different fashion: to embrace an anomaly that seems like a weak anchor in a frame, to overturn that weak anchor, or to add a new anchor. Future work on insight is likely to uncover other paths to insight besides the three shown in the diagram. (Seeing What Others Don’t)
Other people weren’t wrong, they were just following one path.
The Triple Path Model shows why earlier accounts aren’t wrong as much as they are incomplete. They restrict themselves to a single path. Researchers and theorists such as Wallas who describe insight as escaping from fixation and impasses are referring to the creative desperation path. Researchers who emphasize seeing associations and combinations of ideas are referring to the connection path. Researchers who describe insight as reformulating the problem or restructuring how people think have gravitated to the contradiction path. None of them are wrong. The Triple Path Model of insight illustrates why people seem to be talking past each other. It’s because they’re on different paths. (Seeing What Others Don’t)
If you’re interested in learning more about the creative process, you really need to read Seeing What Others Don’t (compliment with A Technique For Producing Ideas.)