T08 Homophone processing during speech-in-speech situation and cognitive control implication
Lexical ambiguity is ubiquitous in oral language and sometimes induces comprehension difficulties. Moreover, in ecological situations language is rarely processed without any surrounding noise and one of the more frequent situations of language comprehension is speech-in-speech situations. In the present study we evaluated the cognitive process at work during online sentences comprehension in which comprehension difficulties were manipulated by linguistic ambiguity (using French homophones) and the presence or absence of babble noise (multi-talker situations). Eye movements on a visual scene including four different images (correct target, an incorrect target, a semantic distractor and a phonological distractor) were measured to assess online effects of lexical ambiguity and noise processing during language comprehension. We hypothesized that looks to the incorrect target would increase with ambiguity and that this increase would be amplified with babble noise. Also, looks to the phonological and semantic distractors should be higher in the speech-in-speech situation than in silence. Furthermore, we hypothesize that in more difficult linguistic situations comprehension will be related with the better cognitive control of participants. Consequently, we also evaluated cognitive control performances during three cognitive control tasks (evaluating: attentional control, inhibitory control and updating in working memory abilities). Results showed significant effects of lexical ambiguity and multi-talker situations on behavioral performances and eye movement measures, suggesting that additional difficulty in language comprehension increased cognitive effort and processing. Combination of both difficult conditions induced the lowest performances but the interaction effect suggests a smaller impact of ambiguity in a speech-in-speech situation than in silence. Results also showed that the bigger the interference or difficulty cost in cognitive control tasks the bigger the ambiguity effect in the language comprehension task. Results are discussed in light of the literature linking cognitive control and language processing.