Preschoolers' understanding of mental and bodily reactions to contamination: what you don't know can hurt you, but cannot sadden you.

Evidence of the operation of a biological theory might be found in children's distinction between mental (emotional) and bodily (illness) reactions to contamination. Study 1 explored whether children see emotions as voluntary but illness as outside of intentional control. Three- and 5-year-olds judged that simple volitions were insufficient to alter either outcome. Study 2 suggested that children distinguish reactions mediated by representations from those mediated by physical interactions. Children indicated that knowledge determines mental reactions to contamination, but physical contact determines bodily reactions. Study 3 explored knowledge about particulars of emotional and illness reactions. Most preschoolers did not realize that illness takes time to develop. These data suggest that preschoolers do distinguish between physical and mental reactions to contamination but have a poor understanding of the actual bodily processes involved.