Thesis defense Arjen Stolk (Donders Series 166)

2 September 2014

Promotor: Prof.dr. I. Toni, co-promotors: dr.ir. R. Oostenveld, dr. L. Verhagen

On the generation of shared symbols

Our everyday conversations appear to revolve around our linguistic abilities. But creating mutual understanding involves more than formulating grammatically correct sentences. If a person on the street comes to you and asks directions for a supermarket, the presence of a foreign accent, a car, or the time of the day are just a few contextual elements that will influence your reply. You may decide to speak particularly clearly, give directions on how to drive there by car, or consider convenience stores. Yet, it remains a mystery how we manage to rapidly integrate those contextual elements into a conversation, and produce an utterance that evokes the intended meaning in the mind of our communicative partner.
 
Building on the notion that we select a communicative action on the basis of predictions of the intentions that another might attribute to that communicative action, I investigated how this predictive mechanism is implemented in the brain, and how contextual knowledge can be rapidly integrated into that mechanism. Pairs of participants played a challenging computer game requiring them to jointly solve a series of novel communicative problems, while I investigated the underlying brain processes through various but convergent methods, including magnetoencephalography (MEG), functional magnetic resonance imaging (fMRI), and transcranial magnetic stimulation (TMS).
 
Members of a pair engaged in communication had very similar patterns of neural activity, coming from the same brain regions. This finding suggests that we use our own intention-recognition system to predict how our communicative actions will be interpreted. Moreover, those regions were already active before a new communicative problem was presented. This finding suggests that we can make sensible communicative predictions because we continuously infer and update the knowledge shared with our communicative partner.