Is the Myer Briggs Type indicator (MBTI) a reasonable scientific theory? Background:
MBTI stands for Myers-Briggs Type Indicator. It's a theory that suggests that people can be divided into 16 types, based on the way they percieve and analyse information (whether they make decisions based on logic or their feel, rely more on intuition or direct sensoric perception, and whether they are more on judging or percieving approach to things happen).

All of these "preferences" are fit into the "consciousness model" in the way, in which you can understand the appearance or behavior of a certain "type" by looking what are the dominating preferences (feeling against thinking, sensoric perception against intuition, judging vs percieving).

For a comprehensive overview, see the wikipedia article on the MBTI.
Go here for another discussion of the MBTI.

Questions


Does the MBTI have a fundamental background? 
Were there any scientific experiments conducted?
Are there any "type" theories that are based on actual brain research?
From what I remember, the MBTI has been compared in some studies to the Big Five (or OCEAN) model of personality. If you've not heard of it, the Big Five is the primary theory of personality that is accepted by researchers who do this sort of thing. Here are some papers comparing the two approaches:

Recent comparison and another.

The main point is that a number of the MBTI traits are correlated with the Big Five traits, though the MBTI can be criticised for various reasons (e.g., it's binary approach to personality). I think from what I remember is that the main criticism revolves around the fact that the MBTI has no place for neuroticism whereas the Big Five does.

That should be enough to get you started (e.g., reading their intro and seeing where this has been cited). There's also a somewhat useful infographic available here.