A four-year-old watches as a monkey hand puppet approaches a vase containing a red and a blue plastic flower. The monkey sneezes. The monkey backs away, returns to sniff again, and again sneezes. An adult then removes the red flower and replaces it with a yellow one. The monkey comes up to smell the yellow and blue flowers twice and each time sneezes. The adult next replaces the blue flower with the red one. The monkey comes up to smell the red and yellow flowers and this time does not sneeze.
The child is then asked, "Can you give me the flower that makes Monkey sneeze?" When psychologists Laura E. Schulz and Alison Gopnik, both then at the University of California, Berkeley, did this experiment, 79 percent of four-year-olds correctly chose the blue flower. As their research makes clear, even very young children have begun to understand cause and effect. This process is critical to their ability to make sense of their world and to make their way in it.