I have this subject called Human Factors, which is something like a sociology and psychology class. There is an interesting topic in it called the Maslow's Hierarchy of Needs. Take a look:
Maslow's hierarchy of needs is often depicted as a pyramid consisting of five levels: the first lower level is being associated with Physiological needs, while the top levels are termed growth needs associated with psychological needs. Deficiency needs must be met first. Once these are met, seeking to satisfy growth needs drives personal growth. The higher needs in this hierarchy only come into focus when the lower needs in the pyramid are satisfied. Once an individual has moved upwards to the next level, needs in the lower level will no longer be prioritized. If a lower set of needs is no longer being met, the individual will temporarily re-prioritize those needs by focusing attention on the unfulfilled needs, but will not permanently regress to the lower level.
From the Wikipedia Article [4 November 2008, 14:55]