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The electrophysiology of discourse and conversation

What’s happening in the brains of two people having a conversation? One reasonable guess is that in the fMRI scanner we’d see most of their brains light up. Another is that their EEG would be a total mess, refl ecting dozens of interacting neuronal systems. Conversation recruits all of the basic language systems reviewed in this book. It also heavily taxes cognitive systems more likely to be found in handbooks of memory, attention and control, or social cognition (Brownell and Friedman, 2001 ). With most conversations going beyond the single utterance, for instance, they place a heavy load on episodic memory as well as on the systems that allow us to reallocate cognitive resources to meet the demands of a dynamically changing situation. Furthermore, conversation is a deeply social and collaborative enterprise (Clark, 1996 ; this volume ) in which interlocutors have to keep track of each other’s state of mind and coordinate on such things as taking turns, establishing common ground, and the goals of the conversation. For somebody invited to review the neurocognition of discourse and conversation in a handful of pages, this doesn’t sound too good. Fortunately, others have already recently surveyed the implications of patient research (Brownell and Friedman, 2001 ; Marr, 2004 ), as well as those of fMRI and PET (Ferstl, 2007 ; Ferstl et al., 2008 ). Here, I review the EEG research on discourse and conversation to date, to see what electrophysiology tells us about the systems involved. EEG studies on discourse and conversation have thus far practically all focused on the comprehension of multi-sentence text , and as such they provide a convenient operational defi nition of the domain. However, an important theme developed in this review is that for the processes that extract meaning from language, the classic separation between a single sentence and a whole bunch of them may not be all that relevant.