Observers use gesture to disambiguate contrastive expressions of preference.

We present two studies exploring how participants respond when a speaker contrasts two ideas, then expresses an ambiguous preference towards one of them. Study 1 showed that, when reading a speaker's preference as text, participants tended to choose whatever was said last as matching the speaker's preference, reflecting the recent-mention bias of anaphora resolution. In Study 2, we asked whether this pattern changed for audio versions of our stimuli. We found that it did not. We then asked whether observers used gesture to disambiguate the speaker's preference. Participants watched videos in which two statements were spoken. Co-speech gestures were produced during each statement, in two different locations. Next, an ambiguous preference for one option was spoken. In 'gesture disambiguating' trials, this statement was accompanied by a gesture in the same spatial location as the gesture accompanying the first statement. In 'gesture non-disambiguating' trials, no third gesture occurred. Participants chose the first statement as matching the speaker's preference more often for gesture disambiguating compared to non-disambiguating trials. Our findings add to the literature on resolution of ambiguous anaphoric reference involving concrete entities and discourse deixis, and we extend this literature to show that gestures indexing abstract ideas are also used during discourse comprehension. [ABSTRACT FROM AUTHOR]