Furthermore, in the field of social psychology, the roles of norms are emphasized which can guide behavior in a certain situation or environment as "mental representations of appropriate behavior".[6] For example, it has been shown that normative messages can promote pro-social behavior, including decreasing alcohol use[7] and increasing voter turnout.[8] According to the psychological definition of social norms' behavioral component, norms have two dimensions: how much a behaviour is exhibited, and how much the group approves of that behavior.[4] Both of these dimensions can be used in normative messages to alter norms and subsequently alter behaviors; for example, a message can target the former dimension by describing high levels of voter turnout in order to encourage more turnout. At the same time, norms also can be changed contingent on the observed behavior of others (how much behavior is exhibited). In fact, in Sherif (1936), one confederate was able to affect the development of a group norm related to the autokinetic effect.[clarification needed]