Alignment in Dialogue: Effects of Visual versus Verbal-feedback

It has been shown that restrictions on feedback in communicative tasks have an important impact on how speakers ground their communicative acts and the effectiveness of their communication. Generally speaking, the more interlocutors are allowed to interact, the quicker they solve communicative tasks, and the quicker they converge at a linguistic level on referring expressions for objects under discussion. Whereas the effects of verbal feedback have so far been mainly investigated with respect to linguistic measures, the effects of nonverbal feedback have been thought of as mainly influencing a more affective component or the outcome (efficiency) of communication. However, recent research has shown that visual-feedback (in terms of a shared work space) also has an effect on the smoothness and effectiveness of linguistic communication. In our study we investigated the different effects of visual and verbal-feedback on alignment in a communicative task. In addition to commonly used measurements like the number of words of referring expressions, we also computed the lexical overlap of subsequent descriptions. We found that visual feedback also has effects on linguistic measures, and that differences in communication related to visual and verbal feedback do not necessarily show up in relatively superficial measurements such as number of words per turn.