Introduction
For creating a personality knowledge base, you should believe, understand, what you are. ,how you mingle with other humans, what makes & broke a relationship etc. some knowledge in psychology is good, but not at all important, because you in your current situation (without knowledge of psychology) is almost feeded with infos on psychology(the difference is that you are not able to distinguish between it), since someone has put a name(psychology) into that particular subject people thinks that they need to study that, it's not like that, you know what you are, but you don't get time to think about that you are busy with your life (Human Psychology has also got so much advanced studies, like cognitive science, mind, dream influences, learning, consciousness and the unconscious etc) but lets leave the advanced thing there,) if someone ever put these subjects wisely in a KB, then we are sure that, we can see Artificial Intelligence
How to Create?
The best way to create a personality knowledge base is to use your conversational skills, begin by making simple rules like, hi, how are you , what is your name etc. See this is the first or basic conversation which we humans do when we meet someone(a friend, a relative, a stranger etc.) and then proceed with more and more conversational subject, also make it your own personality,(without feeding any personal details)
Motivation
You can not build one, if your aim is to enjoy or test verbot, there should be a motivation, like "i can do this", "i know how to give intelligence to a program", "i understands a what is called human beings, how that thing work etc) (no need to know programming languages) just use your conscious brain , the aim should be to share your creation with others(with this world), otherwise if you are just creating a personality KB for your own use, then you will never finish it)
So kick start your imagination, good luck :)