Depends on the context of the conversation.

If it’s a casual conversation and they are enthusiastic I’ll let them talk.

If someone is trying to tell me how something is done while they quote the manual I wrote, I’ll cut them off.

I get excited and finish their sentences, then try to take the convo past the basic stuff, but try to share in their interest.

Assuming they are not doing some kind of smug petty explaining they know I already know and there is plenty of time available, I will listen to see if there is something I don’t know about or whether they have any gaps that I could fill in. I mean, talking about things one already knows about is really common.

If they are smugsplaining something I will just cut them off and move the conversation along. If there isn’t time I will say that I am familiar with the topic and ask if they could focus on the relevant parts.

I listen very carefully for any mistakes they make so I can correct them.

depends on the person.

If they really think you don’t know then interrupt and say that you know. If they just want to be listened to, which happens a lot, then listen if that’s ok for the situation.

Honestly, it kind of depends how well you know this person and what kind of relationship you have, but I think it’s best to take the “Yes, and…” approach.

If you like or care about this person, then definitely don’t rudely interrupt them to shut them down by telling them that you already know what they’re saying. Obviously you don’t have to pretend like you don’t know… But people want to feel like what they’re saying matters, so give them the small win of hearing them out, and then affirm them and add something to what they’re saying of you can.

So, here’s an example of what you probably shouldn’t do:

A: “So the other day I was watching a video on painting and I found out that if you mix blue and yellow you–”

B: “Green. You get green. I know that. I know everything about mixing colors. Everybody knows that.”

What would be better in most cases, would probably be something like.

A: “So the other day I was watching a video on painting and I found out that if you mix blue and yellow you get green. And mixing blue with red will give you purple.”

B: “Yeah, totally! And red and yellow gives your orange, right? And I’ve heard it’s also a good idea to have warm and cool versions of all of the primaries, so that you can get more mixing varieties.”

So, you’re both listening and affirming what the other person is saying, and then demonstrating that you know a bit about this too by adding to it. You’re not making A feel useless, stupid or unappreciated. You’re not making yourself look like a rude jerk or a know-it-all.

Obviously it depends heavily on who you’re talking to and what your relationship is. (Some people who are friends love to talk shit to each other for fun, and in that kind of relationship you probably don’t need to be as careful about hurting the other person’s feelings.)

Generally speaking, though, it’s good to remember that a conversation isn’t just about you exchanging information with another person, and so it’s important to consider how other people feel when you talk to them, in my opinion.

D) Excitedly finish their sentence to create a moment of shared understanding

“So you have xyz and then–”

“Oh yeah! B! It’s so cool, isn’t it? And then C and D!”

“Yeah!”

Fist bump

Or at least this is what I would want to happen if I ever actually talked to people. >.>

Totally depends on the scenario, I use all 3. If we’re talking about music, hobbies, personal interest type stuff, it’s usually C, without the “tell them you already know”. I try to show that I know instead of telling. Like if someone’s telling me about a band I already know about, I’ll let them finish and then say something that requires deep understanding of the source. If the discussion is academic, B, but like in a respectful way? Not ‘cutting off’ the other person, more so ‘jumping in’. And that’s so we can both establish what we both know and move on to the more interesting stuff. A is used for authority figures that I have no respect for. I have nothing to say to marching orders.

I normally pretend to not know anything about it, I either don’t correct them. Just listen and use what’s useful to my benefit and ignore what’s incorrect. No one wants to talk with someone who knows everything about a topic.

I would only interrupt to ask clarifying questions to see how far their knowledge goes. There’s many ways to come to know about a thing. Then I might learn something new!

How long are they going?

In my opinion: kind of option B)

The situation you describe is one of those moments where it’s actually appropriate to finish their sentence - so listen to the other person and find an opportunity to do so, or comment (usually somewhat enthusiastically) “Yes, I’m familiar with that!” Possibly adding a short anecdote of how you became familiar with the topic.

They’re still going to want to discuss it regardless, but this way it’s a more productive experience because they now understand that you’re more up to their level of knowledge. So they can move on to higher ideas about the topic rather than get bogged down in exposition.

It is not rude, because you’re showing enthusiasm for a topic they’re sharing with you. People prefer this to spending the time telling someone something they already know.

I would argue that waiting for them to finish can be ruder because it might make it seem like you were focusing on something else while they spoke to a brick wall.

I rarely find myself in this scenario, but depending on the situation I’ll either nod along and wait to add any points I have or will cut them off with a question.

I’d lean towards C.