In what ways do Japanese children overgeneralize conjugation patterns?


(Preface: I'm not well-versed in language acquisition, so the context I've
provided here will be dumbed-down, or perhaps just dumb.)

**Context:** When children acquire their first language, they typically go
through a phase where they take grammatical rules (e.g. "form past tense by
adding -ed to a verb") and apply them in situations where they aren't
applicable (e.g. using * _goed_ as the past tense of _go_ ). This is called
**overgeneralization**. Children acquiring English as a first language
overgeneralize verb conjugations all over the place - "I ated the candy", "She
telled me to do it", etc.

Since Japanese has fewer irregular conjugations than English, I expect
overgeneralization (in the context of conjugation) to be less visible, but I
doubt that it is absent altogether. I have, for example, heard * _iikunai_ as
the overgeneralized negative of _ii_ "good" in place of _yokunai_. (Albeit
this was a child character in an anime, not a real child, so this may not be
representative.)

**Question:** Do children make similar errors with irregular verbs and other
conjugatable words? For example, might they use * _shiru_ as the 終止形 of _suru_
"to do" or * _kinai_ as the negative of _kuru_ "to come"? What about with
irregular honorifics like _irassharu_ , _gozaru_? (I guess children wouldn't
use these as much, since keigo is mastered relatively late...)

I would also be interested in cases where children incorrectly treat non-
conjugatable words as conjugatable, e.g. (to use some examples from the
comments), * _ippakunai_ as the negative of _ippai_ "a lot; much" or *
_kireikunai_ as the negative of _kirei_ "pretty".




There are a lot of ways that these over-generalizations occur doing child
language acquisition. They do in fact occur -- often -- in Japanese. In fact,
I think it is safe to say that they occur in every language.

There's a rather in depth list of examples of some of these over-
generalizations available in the papers referenced below. I will describe one
example here: the over-generalization of ～らせて (e.g. as seen in 遅【おく】らせて) and
～させて (e.g. 食べさせて). Thus many children will say things like:

> おきらせて and おきさせて (＝おこして).

Even earlier than that, Japanese children will often simply use 自動詞 to express
the meaning of a 他動詞, as seen in:

> かあさん、でんしゃ、うごいてくれ。(＝かあさん、でんしゃを **うごかして** くれ)

There are many more papers and likely books written on this subject, but any
Japanese-language introductory book on language acquisition should have a
bunch more examples.

* * *

### References

  * [荒井文雄(2003)日本語における起因他動詞の習得段階－起因他動詞をめぐる誤用のもつ意味－『京都産業大学論集』、人文科学系列第30号、pp.1-38](http://www.cc.kyoto-su.ac.jp/~arai/acquisition%20causative.html)
  * [荒井文雄(2006)日本語における可能表現の習得過程『京都産業大学論集』、人文科学系列第34号、pp.1-23](http://www.cc.kyoto-su.ac.jp/~arai/acquisition%20potential.html)

