Switch - Chip Heath [134]
Psychologists define schema as a collection of generic properties of a concept or category. Schemas consist of lots of prerecorded information stored in our memories. If someone tells you that she saw a great new sports car, a picture immediately springs to mind, filled with generic properties. You know what “sports cars” are like. You picture something small and two-door, with a convertible top perhaps. If the car in your picture moves, it moves fast. Its color is almost certainly red. Similarly, your schema of “grapefruit” also contains a cluster of generic properties: yellow-pink color, tart flavor, softball-sized, and so on.
By calling up your grapefruit schema, we were able to teach you the concept of pomelo much faster than if we had mechanically listed all the attributes of a pomelo. Note, too, that it’s easier to answer the question about the blend of pomelo and orange juice. You know that grapefruit juice blends well with OJ, so the pomelo schema inherits this property from the grapefruit schema. (By the way, to be complete, Explanation 1 is itself full of schemas. “Citrus fruit” is a schema, “rind” is a schema, and “tangy” is a schema. Explanation 2 is easier to parse only because “grapefruit” is a higher-level schema— a schema composed of other schemas.)
By using schemas, Explanation 2 improves both our comprehension and our memory. Let’s think about the two definitions of “pomelo” in terms of the inverted pyramid structure. What’s the lead? Well, with Explanation 1 the lead is: citrus fruit. After the lead, there is no clear hierarchy; depending on what catches people’s attention, they might remember the rind info (“very thick but soft and easy to peel away”) or the color info (“light yellow to coral pink”) or the juiciness info or the taste info.
With Explanation 2, the lead is: grapefruit-like. The second paragraph is: supersized. The third paragraph is: very thick and soft rind.
Six months from now, people will remember—at best!—the lead of our story. That means that with one story they’d remember “fruit” or “citrus fruit.” With the other story they’d remember “grapefruit.” The second story is clearly better—it isn’t a judgment call.
This concludes what will probably be the last psychological discussion of citrus fruit you’ll ever encounter. But though the concept of “pomelo” may not be worth the neurons you just burned on it, the underlying concept—that schemas enable profound simplicity—is critical.
Good teachers intuitively use lots of schemas. Economics teachers, for instance, start with compact, stripped-down examples that can be understood by students who have no preexisting economics schemas. “Let’s say that you grow apples and I grow oranges. We’re the only two people around. Let’s also say that we’d prefer to eat some of both fruits rather than all of either. Should we trade? If so, how do we go about doing it?”
Students are initially taught how trade works in this simplified context. This knowledge, in turn, becomes a basic trade schema for them. Once learned, this schema can be called up and stretched along some dimension. For example, what happens if you suddenly get better at growing apples? Do we still trade the same way we did before? To solve this problem, we’re calling up a schema and adapting it, just as we did in making a pomelo out of our grapefruit schema.
Complexity from Simplicity
Schemas help us create complex messages from simple materials. In school, lots of science courses are taught by clever uses of schemas. Introductory physics deals with simple, idealized situations: pulleys, inclines, objects moving at constant rates along frictionless paths. As students become familiar with the “pulley” schema, it can be stretched in some way or merged with other schemas to solve more complicated problems.
Another nice use of a schema is the solar system model of the atom, which many of us were taught as kids. This model posits that electrons orbit the nucleus, much as planets orbit the sun. This analogy gives students a quick,