Presentations

Abstract

In an event-related fMRI study, we investigated to what extent semantic and
referential aspects of language comprehension recruit common or dis-
tinct neural ensembles. We compared BOLD responses to sentences containing semantically anomalous or coherent words, and to sentences containing referentially ambiguous pronouns (e.g., “Ronald told Frank that he...”), referentially failing pronouns (e.g., “Rose told Emily that he...”) or coherent pronouns. Semantic anomaly elicited activation increases in lateral prefrontal brain regions associated with semantic pro-
cessing. Referential failure elicited
activation increases in brain regions
associated with morphosyntactic processing, and additional activations
associated with elaborative inferenc
ing if readers took failing pronouns
to refer to unmentioned entities. Referential ambiguity selectively
recruited medial prefrontal regions,
suggesting that readers engaged in
problem-solving to select a unique
referent from the discourse model.
Furthermore, our results showed that semantic anomaly and referential
ambiguity recruit overlapping neural ensembles in opposite directions,
possibly reflecting the dynamic re
cruitment of semantic and episodic
processing to resolve semantically or referentially problematic situations.
These findings suggest that neurocogni
tive accounts of language compre-
hension will have to address not just how we parse a sentence and com-
bine individual word meanings, bu
t also how we determine who’s who
and what’s what during sentence and discourse comprehension

Abstract

In this event-related brain potentials (E RP) study, we explored the possibility to selectively track referential ambiguity during spoken discourse comprehension. Earlier ERP research has shown that referentially am biguous nouns (e.g., “the girl” in a two-girl context) elicit a frontal, sustained negative sh ift relative to unambiguous control words. In the current study, we examined whether this ERP effect reflec ts ‘deep’ situation model ambiguity or ‘superficial’ textbase am biguity. We contrast ed these different interpretations by investigating whether a discourse-level semantic manipulation that prevents referential ambiguity also averts t he elicitation of a referentially induced ERP effect. We compared ERPs el icited by nouns that were re ferentially non-ambiguous but were associated with two discourse entities (e .g., “the girl” with two girls introduced in the context, but one of which has died or le ft the scene), with referentially ambiguous and non-ambiguous control words. While temporally referentially ambiguous nouns elicited a frontal negative shift compared to control words, the ‘double bo und’ but referentially non-ambiguous nouns did not. These results suggest that it is possible to selectively track referential ambiguity with ERPs at the level that is most relev ant to discourse comprehension, the situation model