Looking at a contrast object before speaking boosts referential informativeness, but is not essential.

Variation in referential form has traditionally been accounted for by theoretical frameworks focusing on linguistic and discourse features. Despite the explosion of interest in eye tracking methods in psycholinguistics, the role of visual scanning behaviour in informative reference production is yet to be comprehensively investigated. Here we examine the relationship between speakers' fixations to relevant referents and the form of the referring expressions they produce. Overall, speakers were fully informative across simple and (to a lesser extent) more complex displays, providing appropriately modified referring expressions to enable their addressee to locate the target object. Analysis of contrast fixations revealed that looking at a contrast object boosts but is not essential for full informativeness. Contrast fixations which take place immediately before speaking provide the greatest boost. Informative referring expressions were also associated with later speech onsets than underinformative ones. Based on the finding that fixations during speech planning facilitate but do not fully predict informative referring, direct visual scanning is ruled out as a prerequisite for informativeness. Instead, pragmatic expectations of informativeness may play a more important role. Results are consistent with a goal-based link between eye movements and language processing, here applied for the first time to production processes.