Watching the eyes when talking about size: An investigation of message formulation and utterance planning

In two experiments, naïve participants took turns telling each other to click on a target picture while gaze was monitored. Critical trials included a contrast picture that differed from the target only in size. In both experiments, the timing of speakers' fixations on the contrast predicted whether the contrast was encoded in a phrase with a pre-nominal adjective (the small triangle) or a post-noun repair (the triangle...small one). In Experiment 1, fixations to the contrast were delayed for adjectives in post-nominal phrases (the square with small triangles). In Experiment 2, which used a more complex display, delayed gaze at the contrast was correlated with use of a pre-nominal modifier in disfluent productions (thee uh small horse). The results provide insight into the interface between message formulation and utterance planning. They also support the hypothesis that one role of disfluency is to provide speakers with time to reformulate messages and utterances.