This work contrasts two views of the process of participating in dialogue. One holds that incremental, interactive adjustment to the interlocutor is of primary importance regardless of cost. The other holds that cognitive cost is critcal, with on-line adjustments less favoured than less costly global settings. An experiment using the Map Task, a route communication task (Brown et al, 1983; Anderson et al., 1991) tests these proposals. Speakers produced route descriptions for absent listeners in a factorial design contrasting levels of time pressure (1 minute v unlimited) and feedback (some, none). Time pressure was presented as a single global indication of the time limit. Feedback was available solely via a square moving across the map and purportedly representing the listener's eye fixations, but actually directed by an experimenter toward pre-arranged sequences of correct and incorrect landmarks. Twenty-four subjects produced monologues in all 4 conditions.
The interactionist position predicts strong effects of the feedback,
while the cost-based approach predicts strong effects of time
pressure. Measures of listeners' attention (genuine eye fixations), of
conversational structure (conversational transactions), and length in
words all show the same effects: robust changes with time pressure
(all F-values at p 
.05) and little effect of feedback. We discuss
these effects with respect to a model of the speaker's priorities in
spoken dialogue.