Cultural question: Why「本当？」and「んだ？」are so popular?


This style of communication is very different from English.

When saying something to someone, 本当？？ is a common response.

Also, for example if someone said 決めた！, a common response might be 決めたんだ！
できた！できたんだ！ ついた！ついたんだ！ etc.

This is weird when I do it in English. For example, speaking to my partner...

Him: Oh, this is like this...

Me: Oh, really??

Him: Yeah...(I just said that dude wth)

So I have to remind myself not to do this in English.

Any comments on the reason for this style of communication?




Your question is a little bit vague, but I am going to try and answer the
question I think you're asking.

It appears to me that your confusion stems from the fact that
[backchanneling](https://en.wikipedia.org/wiki/Backchannel_\(linguistics\)) is
much more common - and oftentimes more emphatic - in Japanese than in English.
The Japanese term for this is [あいづち](https://en.wikipedia.org/wiki/Aizuchi),
and the discrepancy between its prevalence in Japanese and English is a
reasonably well known pain point for speakers of either language trying to
acquire the other one. Here's a [brief article about
it](https://guidable.co/move_to_japan/back-channeling-in-japanese-aizuchi/).

There is some debate in the comments about how reasonable it is to be confused
about the usage of particular phrases like `本当？`, but I think this misses the
forest for the trees. Different people are going to favor different
expressions, but what is important to remember here is that backchanneling is
a fairly significant part of conversation in Japanese, and that sometimes
things are said primarily just to backchannel and don't mean much of anything
at all. To quote the wiki article I linked:

> Aizuchi are frequently misinterpreted by non-native speakers as the listener
> showing agreement or fully comprehending what is being said.

You should also take a look at [this
question](https://japanese.stackexchange.com/questions/4012/how-can-i-
differentiate-agreement-with-the-person-and-agreement-with-the-idea), which is
very related.

