Children's knowledge of contagion and contamination as causes of illness.

Children's knowledge of contagion and contamination as causes of illness was examined in 3 experiments. In Experiment 1, preschoolers and children in grades 1 and 3 were shown videotaped segments of puppets with colds and toothaches who explained their ailments in terms of contagion and immanent justice. The children were instructed to evaluate and correct the puppets' explanations and, in addition, to indicate the possible effects on health of drinking milk that had come into contact with objects such as a cockroach, used comb, and spoon. Even preschoolers displayed some knowledge of contagion and contamination. However, compared to the third graders, younger children were less likely to reject proximity to a sick person and naughty behavior as causes of toothaches. They were also more likely to indicate that to drink milk that had come into contact with a spoon was unhealthy. In Experiment 2, preschoolers rejected the proposition that an ailment caused by accident (i.e., a scraped knee) is contagious and, in Experiment 3, they generally accepted that contamination through contact with a dirty spoon can be prevented by washing. Altogether, preschoolers have a more substantial knowledge of contagion and contamination than has been estimated previously. The results are discussed in terms of children's ability to understand causal relations.