Presentations

Abstract

Differences in native and nonnative sentence processing may surface most clearly around parameters that are not shared between L1 and L2. We investigated whether differences between Spanish-Basque bilinguals exist in processing related to the particular constraints of the ergative-absolutive case system of Basque, which is not present in Spanish, but not in processing related to number agreement which occurs in both languages. In an event-related FMRI experiment, we tested this hypothesis by examining the cortical networks recruited for reading in Spanish-Basque bilinguals. Highly proficient nonnative and native speakers of Basque read sentences containing violations of ergative case assignment or violations of number agreement as well as correct sentences (e.g., “Gizonak lehiatilan jaso ditu sarrerek/sarrera/sarrerak goizean”, respectively, approximate translation: “The man at the box office has received the tickets-erg/ticket/tickets in the morning”) while performing an acceptability judgment task. Preliminary results (6 nonnative and 16 native speakers) showed that ergative case violations and number violations similarly elicited activation increases compared to correct sentences in the right inferior parietal lobule and the precuneus while number violations elicited additional activation increases in middle and inferior frontal cortex, consistent with reports for morphosyntactic agreement errors. Compared to native speakers, nonnative speakers engaged the medial prefrontal cortex more strongly while processing ergative case violations and number violations, suggesting that they engaged additional cognitive resources to arrive at the same behavioral outcome. These latter effects, however, did not seem to differ between the ergative case and number violations. Thus, our preliminary results support the hypothesis that while morphosyntactic processing is quantitatively different in the two groups, native and nonnative speakers do not show qualitatively different responses when processing morphosyntactic features that are specific of the L2.

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