Severance

TL;DR: I think the design of the room, combined with the activity in it based on previous experience is exactly what you'd expect Cold Harbor to be. It is the ultimate test to see if the barriers are holding after taming the tempers.

I think you're right on the money - I just have a slight point to add. Remember how Mark bought this crib at some point. He had something to prove when he said that he was pretty handy. Back then, it was sort of funny to Gemma as she dismissed his statement by calling him 'handsy'.

When Gemma had her miscarriage and Mark started actually building the thing, failing miserably, it was very painful for Gemma.

So when Jame keeps asking if the barriers are holding, he wants to know if the tempers are tamed enough to not even have the most painful moments awaken something in this Cold Harbor Gemma. Considering the bad situations we've seen, where the barriers did hold (dentist, thank-you note writing), this one is much more emotional, much deeper rooted than the others.

They take the single most excruciating moment of her life, find some reference to it that is not too overt, and see if it generates any kind of reaction. When it doesn't, and she complies, even without questioning a why, Jame knows he's created a severance barrier so strong, it's pretty much perfect.

What I'm getting from the final episode is that they have a rudimentary severance process in place. Let's call it the Mark One (ha). Now Gemma is sort of like a test subject for a better severance, which will not only make the innie more compliant, but it will also make it possible to create new innies for any situation an outie does not want to experience.

The most important pro of this: Your innie will not have a complete life, i.e. their social interactions will be limited, therefore they will not develop any kind of social intelligence. This creates a situation wherein the innie will feel like they have no choice to accept their hellish life. Remember: for an innie, there is no time between activation and deactivation. They are continuously going to the dentist. But as there is no possibility to discuss this with others who have a shared experience, there is no option of questioning, no road to rebel.

The first iteration of Cold Harbor illustrates this perfectly. Gemma's tempers have been tamed enough for her to accept her situation and be compliant. The emptiness of that innie Gemma's life (the pristine white room with just a crib in it) is designed for nothing to alter her situation, and thus, her tempers, to make her less compliant over time.

It leads one to wonder if what the Eagans are doing is not, in basis, a good thing. They will create the perfect life for their constituents: no pain, no sadness, for any situation you don't want to experience, you will just create an innie and you'll have no memory of the ordeal. Like the senator's wife in childbirth. Of course the question is whether this is ethical, it negates any right the innies might have as pilots of the outies vessel. And of course, the balance between good things and bad things are what makes us human, that's a fact of life.

I'm definitely in the 2nd camp. They were trying to prove the effectiveness of the segmentation of the brain.

I also think being able to prove that the 25th segmentation of Gemma's brain can still split off solidly enough to overcome that individual's most painful moment says something beyond iMark.

Being able to prove that the chip can provide 25 different "personalities" could be useful in many contexts, and the potential marketing for Lumon would be strong.

It was the perfect test, testing the limits of being severed.

My questions: Why wasn't Mark turned into an Innie when going into CH? Technology upgrade for Gemma?

Is Gemma the only one being tested? If iMark is working on Gemma, what are the other innies working on?