The idea is that a human mind is a collection of intelligent agents, acting in committee. We call someone well-integrated if their committee works well, hands off to each other as appropriate, and generally gets the job of operating the body done properly. If someone has a quarrelsome committee, we call them a multiple personality because we're never sure which agent is going to be in charge or whether they will hand off authority correctly when it's the turn of a different agent. (An orderly transition involved briefing your relief on what is going on and what they should be doing.)
This is probably too dense a description and I'll need to unpack it further, but it's an okay first pass. Thoughts, opinions, rebuttals?