In many languages, starting a sentence or an utterance with something other than the subject is a marked option which has to be licensed by some discourse function, as in the case of questions (1) or so-called topicalization (2).
(1) What did she say? (2) That/*it I don’t like. (I’d rather have some …)
In English, topicalized constituents are normally stressed and invoke a notion of contrast; an unstressed personal pronoun is not felicitous, as shown in (2). In the mainland Scandinavian languages, Danish, Norwegian and Swedish, preposing of unstressed pronouns is quite common as a way to connect an utterance to the preceding context, as illustrated by the Swedish example in (3).
(3) A: Var är cykeln? [where is bike-DEF] B: Den ställde jag i garaget. [it put I in garage-DEF.]
In order to find out when this type of preposing is used in dialogue, Filippa Lindahl and I carried out a search in the Nordic Dialect Corpus, a 2.5 million word corpus of spontaneous conversations (Johannesen et al 2009). In my talk I will show that the strategies used are in line with the three types of thematic progression, proposed by i.a. Daneš (1974).