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Preoperational children exhibit centration, the tendency to focus on one part of a stimulus or situation and exclude all others. For example, a boy may believe that if he wears a dress, he will become a girl. He focuses entirely on the appearance (the dress) rather than the other characteristics that make him a boy.

Centration is illustrated by a classic task that requires the preoperational child to distinguish what something appears to be from what it really is, the appearance–reality distinction. In a classic study illustrating this effect, DeVries (1969) presented 3- to 6-year-old children with a cat named Maynard (see Figure 7.3). The children were permitted to pet Maynard. Then, while his head and shoulders were hidden behind a screen (and his back and tail were still visible), a dog mask was placed onto Maynard’s head. The children were then asked, “What kind of animal is it now?” “Does it bark or meow?” Three-year-old children, despite Maynard’s body and tail being visible during the transformation, replied that he was now a dog. Six-year-old children were able to distinguish Maynard’s appearance from reality and explained that he only looked like a dog.

One reason that 3-year-old children fail appearance–reality tasks is because they are not yet capable of effective dual encoding, the ability to mentally represent an object in more than one way at a time (Flavell, Green, & Flavell, 1986). For example, young children are not able to understand that a scale model (like a doll house) can be both an object (something to play with) and a symbol (of an actual house) (MacConnell & Daehler, 2004).

Figure 7.3 Appearance vs. Reality: Is It a Cat or Dog?

Young children did not understand that Maynard the cat remained a cat despite wearing a dog mask and looking like a dog.

Source: DeVries, R. 1969. Constancy of generic identity in the years three to six. Monographs of the Society for Research in Child Development, 34(3, serial no 127), May. With permission from Blackwell Publishing