Introverted iNtuition is a personality function that constantly gathers information, and sees everything from many different perspectives. As the dominant player in a personality, it has the effect of constantly bombarding the psyche with new information to consider. Introverted iNtuition is sort of like a framework for understanding that exists in the mind. As something is perceived, it is melded into the existing intuitive framework. If an entirely new piece of information is perceived by the Introverted iNtuitive, that person must redefine their entire framework of reference. So, Introverted iNtuitives are constantly taking in information about the world that needs to be processed in a relatively lengthy manner in order to be understood. That presents quite a challenge to the INFJ. It's not unusual for an INFJ to feel overwhelmed with all of the things that he or she needs to consider in order to fully understand an idea or situation.
When Introverted iNtuition dominates the INFJ such that the other functions cannot serve their own purposes, we find the INFJ cutting off information that it needs to consider. If the psyche is presented with information that looks anything like something that Introverted iNtuition has processed in the past, it uses Extraverted Feeling to quickly reject that information. The psyche uses Extraverted Feeling to reject the ideas, rather than taking the information into its intuitive framework, and therefore potentially causing that framework to be reshaped and redefined.