The expression information structure refers to the way in which information is packaged in relation to the context and the previous knowledge of the interlocutors. The status of the information is considered with respect to the addressee’s knowledge and can be codified as new or old. Consider for example the discourse reported below.
wh
A: gianni buy what
B: gianni house buy
‘What did Gianni buy?’ ‘Gianni bought a house.’
The sign house indicates to the addressee that Gianni did not buy a car or a bike, but a house. In this case, house represents the new information which was implicitly selected among a set of other possible entities. These possible entities are called alternatives, and the new information item is considered a focus (PRAGMATICS 4.1).
On the other hand, in the same sentence, the proper name gianni is known both by the speaker and the interlocutor. Since both of them understand which specific individual this name refers to, it is considered a topic (PRAGMATICS 4.2). Topics are generally identified as old or given information since they are shared between the speaker and the addressee.
Another relevant notion related to information structure is contrast. Contrast is a more general notion and it can apply to both the focus and the topic. Contrastive focus (PRAGMATICS 4.1.3) is used to introduce a new piece of information in substitution of a previously given piece of information. Contrast can also apply to two or more topics (PRAGMATICS 4.2), when previously mentioned entities are contrastingly compared.
Information structure concerns the organisation of sentences and the sentence internal organisation of units of information linked to larger pieces of text. This differs from the discourse structure, which concerns the way in which sentences are related in a broader context. These two levels can overlap.
Information structure in LIS can be identified by means of syntactic, morphological, or prosodic cues. The present section provides a description of focus, topic and the non-manual markers involved in their realisation.