One of the authors and his wife were in a small cafe in Italy, where they ordered two glasses of wine. The owner did not have two identical glasses, so he carefully adjusted his pour to compensate for the differing shapes. The photo shows the result and nicely illustrates an adult’s ability to display conservation.

The “wild boy of Aveyron” was a French child who, in the late 1700s, was apparently lost or abandoned by his parents at an early age and had grown up with animals. At about eleven years of age, he was captured by hunters and sent to Paris, where scientists observed and tried to help him. What they saw was a dirty, frightened creature who trotted like a wild animal and spent most of his time silently rocking. Although the scientists worked with the boy for more than ten years, he was never able to live unguarded among other people, and he never learned to speak. In other, more recent cases, children have been rescued after spending their early years isolated from human contact and the sound of adult language. Even after years of therapy and language training, these individuals are not able to combine ideas into sentences (Rymer, 1993). Such cases suggest that there is a “critical period” for learning language and that in order to do so, we must be exposed to speech before a certain age.

[Reference: Rymer, R. (1993). Genie: A scientific tragedy. New York: HarperCollins.]

[Source: Adapted from Bernstein, D.A. (2019). Essentials of Psychology (7th ed.). Belmont, CA: Wadsworth Cengage Learning.]