Children start showing a rudimentary sense of moral understanding around four years old, during the preschool years. Their initial sense of right and wrong is quite crude, and based mainly on what adults tell them or what behavior has brought punishment. A few years later, when children are about seven, they begin to grasp the importance of universal rules to govern behavior. Initially, they apply rules in simplistic and rigid ways (“Ooh, you said ‘stupid’! You’re not supposed to say ‘stupid’!”). With time, they develop a better understanding of the purpose that rules serve. Nonetheless, some capacity to respond to the feelings of others is evident as early as infancy, and even four-year-olds can distinguish between prohibitions that serve a true moral purpose, such as protecting people from harm, and those that simply express a preference, such as not sitting on the couch.