From "I dance" to "she danced" with a flick of the hands: Audiovisual stress perception in Spanish

When talking, speakers naturally produce hand movements (co-speech gestures) that contribute to communication. Evidence in Dutch suggests that the timing of simple up-and-down, non-referential "beat" gestures influences spoken word recognition: the same auditory stimulus was perceived as CONtent (noun, capitalized letters indicate stressed syllables) when a beat gesture occurred on the first syllable, but as conTENT (adjective) when the gesture occurred on the second syllable. However, these findings were based on a small number of minimal pairs in Dutch, limiting the generalizability of the findings. We therefore tested this effect in Spanish, where lexical stress is highly relevant in the verb conjugation system, distinguishing bailo, "I dance" with word-initial stress from bailó, "she danced" with word-final stress. Testing a larger sample (N = 100), we also assessed whether individual differences in working memory capacity modulated how much individuals relied on the gestures in spoken word recognition. The results showed that, similar to Dutch, Spanish participants were biased to perceive lexical stress on the syllable that visually co-occurred with a beat gesture, with the effect being strongest when the acoustic stress cues were most ambiguous. No evidence was found for by-participant effect sizes to be influenced by individual differences in phonological or visuospatial working memory. These findings reveal gestural-speech coordination impacts lexical stress perception in a language where listeners are regularly confronted with such lexical stress contrasts, highlighting the impact of gestures' timing on prominence perception and spoken word recognition.