Psychology Today, Feb 1988 v22 n2 p12(1)
Anatomy of analogy. (experiment on analogy perception ) John Rubin.
Full Text: COPYRIGHT 1988 Sussex Publishers, Inc.
Anatomy of Analogy
The atom is like a miniature solar system: Electrons revolve around a nucleus the way planets orbit the sun.
Analogies such as this one, though imprecise, help us see things in a different light. Often they provide solutions to a problem by allowing us to take knowledge gained in one context and apply it in another. Curiously, however, we don’t always know a good analogy when we see one.
A few years ago, psychologists Mary Gick and Keith Holyoak had students read a story about a patient with an inoperable stomach tumor. A certain kind of ray could destroy the tumor, but if beamed at sufficiently high intensity to be effective, it would also destroy healthy tissue on its way to the tumor. A lower-intensity beam would spare the healthy tissue but would be ineffective. How can the tumor be wiped out without destroying healthy tissue?
Before trying to solve this problem, the students read an analogous story about a general’s planned takeover of a dictator’s fortress. An all-out attack would succeed, but at high cost: A large column of soldiers would detonate mines planted along the roads leading to the fortress, destroying many neighboring villages. Small platoons, however, could pass through safely. The general’s solution: He divided his troops into small groups, sent each to the head of a different road and had them march simultaneously on the fortress. The groups converged, and with their combined force defeated the dictator.
Even though the stories were presented back to back, only 30 percent of the students solved the radiation problem. The rest did not realize that they could recast the general’s solution in medical terms: A number of low-intensity beams could be aimed at the tumor from different directions, passing safely through healthy tissue; the combined force of the beams would destroy the tumor.
A recent series of follow-up studies suggests why most students failed to see the analogy (Memory and Cognition, Vol. 15, pp. 332-340).
Holyoak and researcher Kyunghee Koh asked students to solve the radiation problem after reading a story about a physics lab that used a very expensive light bulb in some of its experiments. The filament in the bulb was broken, but could be mended with a high-intensity laser beam. However, a beam of that intensity would shatter the glass. A lab assistant decided to try aiming several weaker laser beams at the filament and successfully fused the pieces together. After reading this story nearly 70 percent of the students were able to solve the radiation problem.
Why did students do better by first reading the bulb story? Holyoak and Koh suggest that two factors are at work in discovering the analogy. One is the similarity of the structure of the two stories. The other is the similarity of the stories’ surface details. The bulb story not only matches the radiation problem structurally but also in detail: Rays are similar to laser beams, for example. In contrast, the general’s story, though structurally similar, diverges from the radiation problem in surface detail: Troops are not easily thought of as rays, and a dictator in a fortress is not much like a tumor.
Using different versions of the bulb story, Holyoak and Koh have confirmed that whether people can see an analogy between two situations depends on a combination of the structural and surface similarities between them. This is a curious finding, though, since what we usually mean by analogy is a connection at an abstract level. Indeed, what makes an analogy powerful is its freedom from irrelevant surface details.