This article offers a look at Maslow's Hierarchy of Needs, newer versions of the same, and the flaws inherent in it. It offers an interesting look at how humanity functions. These principals and this outlook can be applied in world building to the peoples you create. Take a look and see which if this might apply to species you have created. Remember that a basic grasp of human psychology and the history of human psychology is very important in world building. While you don't have to be a psychologist, it is recommended that you do at least a bit of reading.