Beat gestures facilitate lexical access in constraining sentence contexts

Even though we can have successful conversations without seeing each other (e.g., in phone conversations), visual cues can further support speech comprehension. For example, speech is often produced together with co-speech hand gestures. Beat gestures specifically tend to co-occur with prominent words in a sentence, typically aligning to the stressed syllable. Hence, the alignment of beat gestures with specific syllables can affect spoken word recognition. For example, a beat gesture produced and aligned to a given syllable biases participants to perceive stress on this syllable. However, previous studies have primarily tested words in isolation and words with lexical stress competitors (e.g., CONtent vs. conTENT), where the beat gesture was crucial to disambiguate the word. Hence, it is unclear if beat gestures also support lexical access in more naturalistic conditions, such as when hearing words without a lexical stress competitor (e.g., Dutch LEger; English ARmy) in semantically constraining sentences. To answer this question, we presented participants with videos of a talker producing semantically constraining sentences containing a critical disyllabic sentence-final target in a lexical decision task. The target was either produced without a gesture or accompanied by a beat gesture aligned to the first or second syllable. Response times showed that participants were generally faster when the target was presented together with a beat gesture, regardless of its within-word alignment. Moreover, we found that this facilitatory effect was larger for words than pseudowords. These results provide evidence that beat gestures – even when they are not essential for successful speech comprehension – affect lexical access in highly constraining contexts.