Rational behavior is considered to be a decision-making process based on making choices that result in an optimal level of benefit to the individual. The assumption of rational behavior implies that people would rather take actions that are beneficial to them than actions that are neutral or detrimental to them. Economic theories are based on the assumption that all economic entities behave rationally. This paper defines economic, as people or organizations entities involved in any of the four basic economic activities: production, distribution, consumption and resource management. Economic actors can be individuals, male groups (such as a family or a group of roommates) or large organizations such as government agencies or multinational corporations. Economics talks about how these actors behave and interact while participating in economic activities. This paper investigates the behavior of individual economic entities - people. Both historical perspectives and contemporary research on this topic are observed and their implications for economic theory(s) of rationality are discussed. Economics is a social science - it talks about people and how to organize in order to meet their needs and improve welfare. Ultimately, economic behavior is human behavior. Sometimes institutional forces seem to take over (witnessing the tendency of some bureaucracies to expand over time), but if we look closely at economic results, we see that they are ultimately determined by certain human decisions. Therefore, economists have traditionally used, as a starting point, a kind of statement of motivation behind economic actions.