From the short story and other convos with Carpenter, the Thing doesn't need to "act" to hide inside someone.
It discovers that unlike itself, humans have a central intelligence organ (it mistook the brain for a giant tumor), and it described its conciousness as a "search light".
When assimilating humans slowly, it just switched on "autopilot". Ie, the man was stilling thinking/acting, the Thing let the brain carry on, none the wiser, even when the neurones of the human were secretly Thing cells, they still operated the same way. The Thing could even destroy memories (of the man being attacked) with static shock in the brain tissue.
Thats the most terrifying part. You're still you in terms of mind, but the substance you're made of is alien.

In the comics The Thing does exactly what you said. It makes it's way to Argentina, and slowly assimilated the US military that was stationed there. It gets really bad.

We need more Monster VS movies, the idea that Calvin(Life) gets a sequel & the plan to use a captured Thing(John Carpenter) to fight it would be monstrously & cataclysmic but amazing if done right and violent.

I've got all 3 movies in my collection. The original "Thing from another world" from the 1951 was actually a sanitized version of the book, while the Carpenter remake is closer to the creature in the original book.
The producers of the 1951 version felt that if they made it in accordance to the way it was described in the book it would be too scary for a 1950s audience.
The remake, in my opinion, was much more plausible in that it's a creature that reproduces by assimilation and conversion of other lifeforms. This means it functions with a form of highly evolved instinct rather than sentient intelligence.

I agree with another commenter about the Thing not assimilating the brain of the animal or human right away because it knows instinctually that the copy must behave normally to avoid detection. That would mean leaving the host's brain and personality intact, at least during the early stages of assimilation if the host was exposed to only a few cellular particles of the Thing.
The character named Fuchs explains this when he recommended that everyone prepare their own meals and eat only canned foods because it was theoretically possible for a person to be taken over by just a few particles of the creature.

This is supported in a scene of the Carpenter remake when Norris is looking out a window but then doubles over in pain, as if he's having a heart attack. That could have been the thing cells in the process of taking him over, but he thought he was experiencing chest pains. It was only when he was knocked out that the thing inside finally revealed itself.
I think it's possible that the thing slowly assimilates a human so that the human feels only slight discomfort during the process. Just like when cancer is slowly growing in a human body. The person doesn't know it's there until it reaches a critical point of growth and affects the other organs.

There is precedence in nature for this. There's a fungus that infects ants that slowly takes over their bodies while they are going about their normal ant routines. Only when the fungus is ready to reproduce does it take over the ant's brain causing it to leave the colony and climb high enough for spores to be released.
Perhaps the Thing is similar in that it takes over the animal or human slowly enough to not cause suspicion but when it's ready to spread itself, or is discovered, it finally takes over the brain and reveals its true self.

Just my opinion as a sci-fi writer, and avid collector of these kind of sci-fi stories.

In my opinion, the Thing is the most horrifying alien creature in science fiction, second only to "The Blob".
The Blob is my all time favorite because it's like a giant amoeba that consumes all lifeforms, cannot be burned, and cannot be killed conventionally. The only way the Blob was stopped was by freezing it solid, but it was still alive.
And like the Thing, the Blob could theoretically be spread by cutting pieces off and each piece would become a new Blob.

In WGT the Thing had psychic powers, which explains the organism's ability to communicate between assimilated bodies.

I love how in the comics they show they can copy plants if they wanted to, but only seems to copy animal species.

Dude--- has anyone ever considered how insanely well everyone is taking this situation in the movie? If I witnessed any of these events in real life, i'd be too disturbed to function.

At least they didn't run into the X Parasite from Metroid Fusion and Metroid Dread.

Here's a prequel (of sorts) to John W. Campbell's "Who Goes There?" >> "In Amundsen's Tent" by John Martin Leahy. To my mind, "Norris Spider Thing" is the most nightmarish incarnation of the alien entity. Thanks, Lore Lockdown.

My favorite movie of all time. And it's "ok but could've used less executive meddling by the studio and a less-rushed schedule" companion piece. And this is one of the few videos I've seen that really seems to do it justice. Excellent work.
How about a look into the mutated Tardigrades from Harbinger Down? That movie was made because of said executive meddling that replaced the special effects company's practical effects from the 2011 The Thing prequel...

How many memories can it absorb before it becomes confused, or even develops different sentiments and goals. That may be the thing that prevents it from taking over the hole world.

Thing Norris did a good job of extracting blood.

I always thought the Palmer Thing was the most disturbing one

You should read The Things by Peter Watts. It is like John Carpenter's The Thing but told from the alien's perspective. The "things" in the title are the humans and dogs. it is free at Clarkes World Magazine website.

Brian Aldiss, the British sf author, wrote a novel about a Thing-like alien threat that attacks a human galactic civilization, and how humans counterattack. The "things" learned to become insect sized, like flies, to infect the populations of entire planets. But advanced bioscanners, and nearly countless small hunter drones, over time eradicated them. When the things took over a planet and had no more opposition to conspire against, and had no way to get off-planet to infect others, they tended to "get stupid" and take the form of dinosaur like creatures, to fight with each other. The book came out long before the Carpenter film.

I think its possible for people to be assimilated until "activated". The thing mimics the body perfectly but it can be advantageous for it to let the original intelligence  to continue until its not required and the person simply vanishes as the thing takes over the remaining person.

The Blob if not done already

Fantastic video 😈👍

Generator wasn't destroyed it was taken, Blair needed a power source  "it's gone"

esa entidad es tan monstruosa que da miedo.