Pattern V-더니 Past Observation of the Speaker

V-더니 is used to describe an observation of the speaker about people or things, or a change that came to be known through personal experience, and always precedes a statement resulting from that observation. A good example in English/Korean of how this pattern would be used: "my friend used to eat a lot of ice cream before더니 these days he even hates the sight of ice cream." V-더니 can therefore only be used in the middle of a sentence and can never end a sentence.

The clause before V-더니 can only be in the second or third person, so this pattern is therefore not appropriate to describe things the speaker has done. It is used to describe what the speaker has noticed about the external environment. Warning: while V-더니 cannot be used in the first person, V-았/었더니 can, and will be the object of a different lesson.

Other points about the pattern V-더니

  • the subjects in the clause preceding V-더니 and after it must be the same.
  • the clause after V-더니 must be logically connected to the observation preceding it; i.e. both should be about the same topic.
  • Korean sentences with V-더니 are challenging to translate in English without adding more context to the translations. If you look at the examples below, V-더니 can be translated into different ways to fit the original sentence better.

Examples

예전에 친구가 아이스크림를 많이 먹더니 요즘에 아이스크림을 보기도 싫어해요.
(I noticed before that) My friend ate a lot of ice cream in the past but now he hates even the sight of ice cream.
아침에 구름이 많더니 오후에는 없어졌어요. 
(I noticed) there were a lot of clouds in the morning, but they have all disappeared in the afternoon.
친구가 직장을 다니기 시작하더니 이제는 바빠서 못만나요.
Now that my friend has started working, we cannot meet a lot because he is busy (implies that the speaker and the friend used to meet a lot before).
너희 어릴때는 술집에 못가더니 이제는 갈 수 있구나!
When you were young you couldn't go to bars but I see that you can now!
너는 공부를 안하더니 시험을 망쳤구나.
(I noticed that) You didn't study and so I see you failed your test!
친구가 돈을 많이 아끼더니 부자가 됐어요.
(I noticed that) Because My friend saved a lot of money, he became rich.
친구가 사랑에 빠지더니 많이 달라졌어요.
(I noticed that) My friend has changed a lot after he fell in love.