Beyond simply indicating past tense, what specific nuance does '-았/었었-' add when used in a Korean sentence, and how does this alter the interpretation of the event?

Beyond simple past tense, '-았/었었-' (double past tense) in Korean adds a nuance of anteriority, meaning the action or state occurred even further in the past than a single '-았/었-' implies. It indicates that the action is completed, and the state resulting from that action is also in the past, no longer relevant or continuing in the present. This often conveys a sense of distance, either temporal or emotional, from the event. The use of '-았/었었-' also emphasizes that the speaker's experience or knowledge of the event is from a time even prior to a more recent past event. For example, '어렸을 때 살았었어요' (I used to live there when I was young) implies that the speaker not only lived there in the past, but the period of living there is also long finished and distant from the present. If it were '어렸을 때 살았어요', it would simply mean the person lived there when they were young, without necessarily emphasizing the remoteness of that past. The double past ending communicates that a past state or action is not only over but also has limited current relevance. The interpretation of the event is altered by adding a layer of remoteness, completedness, and a sense that the effects of the past event are no longer ongoing.