IMPRS DOCTORAL DEFENCE: Ronny Bujok

Speech is often accompanied by hand gestures. One of the most frequently used gestures are so-called beat gestures. Beat gestures are rhythmic mostly up-and-down gestures of the hand which do not carry meaning on their own. However, they are generally aligned with important words and stressed syllables. Therefore, the temporal alignment of beat gestures with speech can significantly affect how we perceive someone. In this dissertation I conducted a series of studies testing the effects of beat gestures on speech perception. I found that beat gestures can serve as visual cues to lexical stress. Hence the timing of beat gestures can help disambiguate lexical stress pairs such as CONtent and conTENT. Moreover, beat gestures can also drive speech adaptation: When beat gestures are aligned to specific syllables, listeners learn to perceive lexical stress on these syllables, which persists even in subsequent audio only testing. Finally, beat gestures can generally speed up lexical access of words in a sentence, even when the beat gestures are not strictly necessary. These findings highlight the multimodal character of speech and how even the simplest gestures can have significant and lasting effects on how we perceive speech.