The late night host is entering his fourth week on the air but still seems reluctant to just be himself.

This is Stephen Colbert’s fourth week as host of The Late Show on CBS and one thing is crystal clear: He’s getting there.

And that’s about the only thing that is clear. But if you reverse engineer how he’s looked so far, maybe the most fascinating part of it is guessing whether the character he played on The Colbert Report was closer to his real personality than anyone thought, or whether it will just take longer than expected for him to revert more naturally back to himself.

Casual fans or new viewers may not notice, but the one nagging element of these early shows, in which his improvement and adaptation is otherwise notable, is that there’s still a muffler on the vulnerability and openness — those little bits of light emanating from a normal soul — that increase his likeability.

Oh, there are other things to praise and to possibly nitpick, but this one area currently is the most bedeviling.

Part of what’s confounding about it is that Colbert seems to be protecting himself from being himself in some way — at least from being too open and, if not vulnerable, then softer or more welcoming than he’s used to. And that makes perfect sense. He’s a comedian and actor who has played mostly with irony and satire, which has kept him at a distance from being himself. Except for more intimate interviews, this is one of the rare times that Colbert’s job — what he’s been hired to do — is to actually be Stephen Colbert.

The strangest thing right now is to realize Colbert is the least open book in late night. You know who Jimmy Kimmel really is. And you know who Jimmy Fallon is. (At least to the extent that we know any of these people.) But from their history, from what they’ve revealed about themselves, viewers get the sense that if they were somehow to be hanging out on a weekend with either Jimmy, they’d probably act pretty much the way they do on TV.

That doesn’t yet seem true for Colbert.

Being comfortable in his own skin seems to be taking some getting used to for a man blessed with razor-sharp wit and intelligence, but has often been most engaging and, yes, most likeable, when we glimpse the real person. What was always interesting on The Colbert Report were the smiles, asides, total laughter breakdowns and other such moments when he fell out of character and became, even just for a few seconds, himself.

The first three weeks and into this fourth have been a very interesting tussle with letting go for Colbert. You can see it. In that first week, it felt as if the host of The Colbert Report had been asked to make it a little more real for The Late Show. It was like he had ratcheted down the full-on shtick but was still wearing a mask. He was still performing.

Each night, he seems to let go a little bit, which, in turn, brings him closer to his guests and to the audience. But just when you think a pattern is emerging, Colbert seems to become keenly focused on being a guy behind a desk asking questions. He reverts to a role that’s less the right-wing blowhard of the Report, for sure, but only slightly less detached. And in that moment you wonder, “Is this Colbert being curious or is this him slipping back into the role of a faux reporter or late-night host being a 'serious' interviewer?"

We might not know the answer for a while. Maybe even Colbert doesn’t know. He’s still learning how to do this. We forget too easily that this is all new territory for him. We expected him to waltz in and nail this, with some bumps, and he definitely will. In fact, the future looks very bright for Colbert and The Late Show, especially as he eases into it. Because that’s the thing that his biggest fans and longest-tenured ones truly glom onto – that person underneath the faux news host who wink-winked periodically but, more important, slipped out of character and into the open where we saw the man behind the mask.

The great unknown is whether or not that’s how Colbert prefers it. There’s definitely an art to being yourself on television, especially when you’re also the host. It took David Letterman a while to get comfortable in his own skin — and, interestingly enough, Letterman also struggled early with interviewing celebrities, just as Colbert has.

Where Colbert is more of a showman to Letterman’s curmudgeon, what people will remember in Letterman’s legacy is first and foremost the moments when he was real — and he piled up a lot of those each week with interviews before more famously being remembered for his post-9/11 shows and his post-heart-surgery shows. Those are legendary memories now. But Letterman had been opening himself up to certain guests (and certainly to Paul Shaffer), for years prior.

Colbert is only just starting his fourth week. He’s not there yet with bandleader Jon Batiste, though they have real chemistry and a seeming affinity for one another.

What’s truly encouraging is that whatever layers Colbert is slowly peeling back each week, other elements of his show are improving at a faster pace.

That’s really what you want to see. You want to see progress and improvement as quickly as possible, and the notable part of this early going is how each show seems to improve upon the last.

His celebrity interviews have gotten dramatically better — Kerry Washington is a good example — but can still be better. Not surprisingly, they improved when he approached his subjects just like a guy — say a guy named Stephen Colbert — who was curious about things. The moment when he gets too detached is when it seems like a bit like an anchor or newsman grilling a star.

A good example of when a more human or personal side emerged recently is when he interviewed Malala Yousafzai, the teenaged Nobel Prize laureate from Pakistan. Now, in some ways she’s closer to the "political" interviews he’s far more comfortable doing than show biz stuff, but she’s also only 18 and wholly outside the slick late-show vibe, which forced Colbert to recalibrate his approach.

Of course, the perfect interview was with Vice President Joe Biden — perfect because it was smart and fearlessly intimate and revealing, as both men talked about loss, family, religion and feelings. That side of Colbert was perfect in that he couldn’t totally withdraw into his tough news guy role which, at this point, even he seems to periodically forget is an act. Colbert had to be himself with Biden; he had to be a person, not play a role.

Of course, he also shouldn’t (and doesn’t seem inclined) to ditch the political interviews. They are the defining element of his show and approach as a host so far. There might be too many eat-your-vegetables moments for some viewers, but it’s a welcome relief in the late-night landscape.

The real improvement has come from branching out ever so slowly into more taped bits and to honing his on-stage comedy skills as well — spoofing the Pope’s visit, his continued lambasting of political candidates, etc. Not everything works — and a lot of stuff seems to go a couple of minutes too long (the Hillary Clinton "Heightghazi" riff being a perfect example).

You can feel it, show by show, coming together and feeling more natural. Along with that loosening up, you also get more glimpses of what we at least imagine to be the real Colbert. Early on it was hard to tell if Colbert’s dancing at the beginning of the show and singing with lots of his musical acts was him spoofing the whole idea of a nerdy-looking guy getting funky (this is the kind of second-guessing that happens when a satirist takes over a late night talk show). But now we can probably safely assume that Colbert likes to be a showman, that he likes to be the center of attention and that it might just be an honest attempt to have fun and risk whatever embarrassment might come.

That kind of boldness should be encouraged. It’s what makes Fallon seem appropriately goofy when he does musical bits. It’s the kind of thing that Kimmel did with taped segments and celebrities to really bring out his own personality. And yet, with Colbert we just don’t know yet — that’s part of the deal when you get a guy used to playing characters.

But there was something a little oddly on-the-nose when, this week, he started a new feature called "Stephen Colbert: Who Am Me?" which almost too deliberately nods at the notion that nobody knows the real Colbert yet.

"It’s the first time that I, the real Stephen Colbert, have been on television," he said earnestly to set up the segment.

While it starts off as yet another Stephen-centric bit (which still harkens a little too uncomfortably back to the Report antics), it is simultaneously funny and real as he takes the Myers-Briggs Type Indicator test. Colbert was hilarious and loose, and it was nice to see him continue to try more taped segments. But what stood out was his reaction to the fact that he was an INFP, one of the 16 personality types the test uncovers, focusing on predominant elements — introversion, intuition, feeling, perceiving — that are hallmarks, according to Julie Raynor Gross, the woman administering the test, of "the most brilliant, creative, intellectual minds." Colbert seemed honestly pleased about this (yes, the mask fell off), but Gross added that "sometimes, some people may not see that warm aspect of your personality."

Though Colbert rallied to joke about this, he did seem taken aback and then wondered — a wink at ratings potential — if lots and lots of people could actually love an INFP. Here’s what Gross said: "If you become so attuned to who you truly are, and feel comfortable acting authentically, then you will receive that love."

Colbert: "So, I have to be myself for people to love me?"

It was one of those moments that perfectly encapsulated what some people — including your friendly neighborhood TV critic — are thinking, and it just happened to come in a fun, breakthrough segment on a show that’s trying out new things. Kismet, right?

Well, maybe. But it’s unlikely this happened by accident. The guess here is that the very self-aware Colbert is honestly struggling with the challenge of unwrapping himself, and the best way he knew how to deal with it was a fully taped segment that could at once mock the notion and honestly address it.

The bottom line? It was a good sign. The Late Show is getting better each night, but more importantly, Colbert is slowly getting closer to truly introducing himself.

Email: Tim.Goodman@THR.com

Twitter: @BastardMachine