So I'm no expert in this stuff so just keep that in mind. But yeah, the loops are more when you're trapped in either the extroverted or introverted worlds. You need both to function, and when you're cutting off use of one, it causes problems with the other because there needs to be a flow.

I haven't been able to see where dominant-tertiary loops come from… but in my experience, grip experiences seem to come from stress. That's where mine came from. That's where my ESFP brother's came from.

Oh! I just remembered: my INFP brother experienced an introverted loop for quite some time. He basically did the same nostalgic stuff with his girlfriend everyday. He would re-watch favorite movies and tv shows. He would eat comfort food. He never wanted to do anything new. The desire for nostalgia came from his Si and Fi alienating Ne and Te, so he just desired to experience the same stuff that provided similar feelings. I knew this was a loop because he's normally learning new things, taking up new hobbies, or just curious to experience new things.

I'm thinking as I write so bare with me because I had never really thought much about it. It seems, though, that grip experiences come from prolonged stress. I would say that loops come from a constant failure to solve a problem. I have found that when I'm stumped on a CS problem. My INFP brother ran into this when he was trying to figure of a career for himself—but wasn't having any success for months.

But basically, I am no expert. That's mostly just my experiences. And it's true, as someone pointed out, that there isn't much evidence backing up these two concepts being discussed: they were more or less developed on the Internet. I probably wouldn't type someone by going off of grip experiences and loops… it's more just to analyze after knowing their type.