http://en.wikipedia.org/wiki/Maslow%...archy_of_needs
There are many psychological studies which can be connected to socionic given some minor revision of the theory or idea. Maslow hiearchy of needs is one of them.
I look at maslow's hierarchy of need and if you remove self-actualization which is closely related to esteem, it can be explained mental function developed. The first 4 levels of the hierarchy correspond with the functional development that people go thru.
Our base function is the psychological foundation by which we engage the world. Having a sound body is very important to having a sound mind, thus having the proper physiological needs met is important.
Our creative function is the product we produce in order to acquire material and personal security.
Developing the role function is how we achieve love and belonging, by fulling a role in society and in various organizations or our personal lives, it's not something we are naturally confident in but we fulfill this role without ego and the overconfidence of the ego functions.
Developing the vulnerable function is esteem, where we finally overcome our fears and gain the respect and self-respect we need in order to be fully at peace with ourselves.