Declarative questions in discourse

Questions in spoken dialogues are often uttered in a declarative form. Since more than 50% of these questions cannot be recognized as such without contextual features, a speaker must, at the risk of misunderstanding, have special reasons for using a declarative form instead of an interrogative one. Two experiments were carried out to determine the contextual features that contribute to the use of a declarative question. Dialogues were presented on paper in both experiments. In the first experiment, subjects had to indicate whether a question in the dialogue was originally used in a declarative or an interrogative form; in the second, the subjects had to estimate the speaker's certainty about the correctness of the propositional content of the questions in the first experiment. The experimental results indicate that declaratives are often used for questioning if the speaker wants to verify information already provided in the dialogue and that the use of declaratives significantly correlates with the speaker's degree of certainty about the propositional content of the question. Moreover, from the experimental results it is hypothesized that abrupt changes of topic may decrease the use of declaratives