Hyperfocus on character traits

Some players seem to put so much emphasis on portraying their character's personality that they struggle to do so while also keeping the objective of a given interaction in mind.

If their character is jaded or gruff, they might end up being constantly guarded, curt or suspicious. If the PC is lighthearted and silly, they might have a hard time dialing it back when things get serious. This makes their character flat and less compelling than one with depth, because they don't seem capable of growth.

But (I think) more importantly, it can make social interactions in sessions difficult.

Like, maybe a PC approaches an NPC who has information the party needs. The PC is a calloused veteran who's seen a lot, the NPC is frightened that spilling the beans could land them in trouble.

The GM telegraphs the NPC's whole deal, says things like "it seems like they want to tell you, but they're clearly nervous about something," but the PC misses the opportunity to change up their approach or maybe just misses the cues entirely, because they're so focused on being a tough guy.

It's like some players are so determined to be "in character" that they forget people are complicated. Which is unfortunate, because those moments when the tough guy softens up a bit or when the jokester gets serious--those can be really compelling moments in the game.

I've seen this a bunch of times; in one instance, I had two PCs who got into an argument because one was stubborn and the other was proud and the players felt like they had to act a certain way. The conversation didn't go anywhere interesting; just very circular and frustrating to listen to. Things got heated, so I hit the breaks and talked with each of them. They both admitted to wanting out of that situation, but feeling like they couldn't find a way. Like they were stuck, because their character was defined by these traits. I kind of ended up conducting a sort of acting/improv workshop where we all talked about how to stay true to our characters while allowing for growth, especially in the name of moving the game forward and letting other players portray their characters.

I think players with more thespian leanings avoid this without thinking about it, and having some kind of game/narrative awareness helps, too.