IMPRS DOCTORAL DEFENCE: Cecília Hustá

Effective communication requires speakers to plan what to say while simultaneously comprehending incoming speech, enabling rapid turn-taking. Although both speech planning and comprehension demand attentional resources, interlocutors typically manage these processes concurrently. When they occur at the same time, however, an attentional trade-off may arise, potentially affecting the speed or quality of planning, comprehension, or both. It remains unclear when speech planning takes place during comprehension and which linguistic factors influence this process. This thesis used EEG to investigate the attentional trade-off between speech planning and comprehension. Across several experimental chapters, different approaches were used to examine how planning and comprehension interact. The findings show that speakers can efficiently balance these processes under moderate demands, while capacity limitations emerge when both tasks become more demanding. Moreover, the structure of natural dialogue appears to support turn-taking by reducing attentional demands for comprehension near utterance boundaries, facilitating concurrent planning of the next utterance. Methodologically, this work explores novel approaches to studying speech planning during comprehension, with Rapid Invisible Frequency Tagging (RIFT) showing particular promise for tracking dynamic attentional shifts.