Focus (information structure)


 * "Here we will use focus of a sentence to mean "the information in the sentence that is assumed by the speaker not to be shared by him and the hearer"." (Jackendoff 1972: 16)
 * "Within the framework developed here, the focus of a sentence, or, more precisely, the focus of a proposition expressed by a sentence in a given utterance context, is seen as the element of information whereby the presupposition and the assertion DIFFER from each other. The focus is that portion of a proposition which cannot be taken for granted at the time of speech. It is the UNPREDICTABLE or pragmatically NON-RECOVERABLE element in an utterance. The focus is what makes an utterance into an assertion." (Lambrecht 1994:207)

Subtypes
Two major taxonomies of focus are according to scope and according to the communicative point. The classification of focus according to scope includes the following types:

In cases of argument focus any constituent of a clause, be it subject, object or oblique can be focused. Some authors (e.g. Van Valin and LaPolla 1997) have in their taxonomies narrow focus instead to allow to include verb focus into this taxonomy. The parts of the example sentences in capitals illustrates the narrow focus.
 * argument focus, narrow focus
 * Question: WHERE did you go yesterday?
 * Answer: We went TO THE THEATRE.

In case of predicate focus the whole predicate is in focus. This type is claimed to be a universally unmarked type of focus correlating with the topic-comment structure as the unmarked pragmatic articulation (Lambrecht 1994: 296).
 * predicate focus
 * Question: What has happened to your wife?
 * Answer: She HAS GOT A HEADACHE.

In cases of sentence focus the entire clause is in focus. This type of sentences is also known as thetic sentences or all-focus sentences.
 * sentence focus
 * Question: What has happened?
 * Answer: MY WHIFE HAS GOT A HEADACHE.

The classification of focus according to the communicative point includes the following types:
 * contrastive focus, identificational focus
 * completive focus
 * information focus

Polysemy
Focus is also used in Austronesian languages to refer to a verb-coded system of assigning prominence to arguments; see focus (Austronesian).

Synonyms

 * rheme (in the Prague School tradition)
 * emphasis (in information structure)

Origin
The term focus has been in general use only since c. 1970; it seems that Halliday (1967) and Jackendoff (1972) were particularly influential in spreading the term.