If you've read the page on this site about Episodic Memory (EM for short) you may have started to realise that when we think about anything, the first place our mind tends to go to is the dominant Emotional Imprint or EI we have, for that type of experience (memory is state related) . Now we tend to like to put things in boxes by labeling them, after which we often don't bother to re-examine them. This means that quite often our opinions and feelings about things (including our selves) tend to come prepackaged, labelled and often unexamined and at the roots of this information are our (often outdated) EM's.
What's been said above not only applies to our ideas about who and what we think we are, it also applies to what we believe we're capable of.
NLP will often say that our behaviours are driven by different parts of us. I believe a more accurate way of explaining this is episodic memory. If an episodic memory with a strong emotional imprint has not been integrated or updated,, whenever it is triggered a person will be operating out of the identity, resources, and understanding they had at the age the memory was created, despite the fact that they may have learned many better ways of doing things since that time. NLP 'Parts Work' would have us 'negotiate' with that episodic memory as if it were a distinct personality and update an element of its behaviour through that process. However, as that approach doesn't integrate and update the whole EM (including the age regression) it may not be ecological to all the elements within that EM and result in a return to the original behaviours. (see this sites page on Episodic Memory for more information). Because IEMT updates the entire experience and age progresses the sense of self experinced, the whole memory is healed and updated, so that it is no longer a negative power in a persons life.