Error-Driven Retrieval in Agreement Attraction Rarely Leads to Misinterpretation
"The bed by the lamps were undoubtedly quite bright." Does making this mistake in agreement, "were" instead of "was," make you less likely to notice the oddity of describing a bed as bright? This study shows that normally the answer is No.
Antecedent access mechanisms in pronoun processing: Evidence from the N400
Lexical decisions to a word after a pronoun are facilitated when it is semantically related to the pronoun’s antecedent. These priming effects may depend not on automatic spreading activation, but on the extent to which the relevant word is predicted.
The temporal dynamics of structure and content in sentence comprehension: Evidence from fMRI-constrained MEG
fMRI implicates the TPJ, PTL, ATL and IFG regions of the left hemisphere in the processing of linguistic structure. But what are the temporal dynamics of their involvement? This MEG study provides some initial answers.
Advanced second language learners' perception of lexical tone contrasts
Mandarin tones are difficult for advanced L2 learners. But the difficulty comes primarily from the need to process tones lexically, and not from an inability to perceive tones phonetically.
The role of the IFG and pSTS in syntactic prediction: evidence from a parametric study of hierarchical structure in fMRI
Postdoc William Matchin, with Ellen Lau and Baggett Fellow Chris Hammerly, find a role for the anterior temporal lobe in semantic combination, and a role specifically in comprehension of thematic relations for the Angular Gyrus/Temporalparietal junction
A Direct Comparison of N400 Effects of Predictability and Incongruity in Adjective-Noun Combination
The N400 is modulated both by association and by predictability: but independently? Only slightly, show Ellen and her collaborators, suggesting that its senstivity to both does not come just from trouble integrating a word with its prior context.
The role of temporal predictability in semantic expectation: An MEG investigation
Is prediction of an upcoming item improved when its timing is predictable? Maybe yes for vision and audition, but evidently no for language, argue Ellen Lau and Elizabeth Nguyen.
Spatiotemporal signatures of lexical-semantic prediction
Ellen Lau finds evidence that facilitatory effects of lexical–semantic prediction on the electrophysiological response 350–450 ms postonset reflect modulation of activity in left anterior temporal cortex.
Additive effects of repetition and predictability on lexical semantic processing during comprehension
Word repetition and predictability have qualitatively similar and additive effects on the N400 amplitude in ERP.
Automatic semantic facilitation in anterior temporal cortex revealed through multimodal neuroimaging
Bottom-up effects of context on semantic memory, plumbed by a combination of electroencephalography (EEG), magnetoencephalography (MEG), and functional magnetic resonance imaging (fMRI) measurements in the same individuals.
Dissociating N400 effects of prediction from association in single word contexts
The N400 component in ERP is modulated both by the predictability of the stimulus, and by its congruence with the semantic context. Ellen Lau and collaborators show that the effect of the former is much greater.
A lexical basis for N400 context effects: Evidence from MEG
Within-subject MEG studies on the topography of N400 effects suggest that such effects reflect facilitated access to lexical information, and not difficulty integrating a word with its semantic context.
The electrophysiological response to words during the ‘N400’ time window (approximately 300–500 ms post-onset) is affected by the context in which the word is presented, but whether this effect reflects the impact of context on access of the stored lexical information itself or, alternatively, post-access integration processes is still an open question with substantive theoretical consequences. One challenge for integration accounts is that contexts that seem to require different levels of integration for incoming words (i.e., sentence frames vs. prime words) have similar effects on the N400 component measured in ERP. In this study we compare the effects of these different context types directly, in a within-subject design using MEG, which provides a better opportunity for identifying topographical differences between electrophysiological components, due to the minimal spatial distortion of the MEG signal. We find a qualitatively similar contextual effect for both sentence frame and prime-word contexts, although the effect is smaller in magnitude for shorter word prime contexts. Additionally, we observe no difference in response amplitude between sentence endings that are explicitly incongruent and target words that are simply part of an unrelated pair. These results suggest that the N400 effect does not reflect semantic integration difficulty. Rather, the data are consistent with an account in which N400 reduction reflects facilitated access of lexical information.
The Predictive Nature of Language Comprehension
Data from fMRI, MEG and EEG show that predictive processing plays a central role in language comprehension, for instance by facilitating lexical access, as indexed by N400 effects in ERP.
This dissertation explores the hypothesis that predictive processing—the access and construction of internal representations in advance of the external input that supports them—plays a central role in language comprehension. Linguistic input is frequently noisy, variable, and rapid, but it is also subject to numerous constraints. Predictive processing could be a particularly useful approach in language comprehension, as predictions based on the constraints imposed by the prior context could allow computation to be speeded and noisy input to be disambiguated. Decades of previous research have demonstrated that the broader sentence context has an effect on how new input is processed, but less progress has been made in determining the mechanisms underlying such contextual effects. This dissertation is aimed at advancing this second goal, by using both behavioral and neurophysiological methods to motivate predictive or top-down interpretations ofcontextual effects and to test particular hypotheses about the nature of the predictive mechanisms in question. The first part of the dissertation focuses on the lexical-semantic predictions made possible by word and sentence contexts. MEG and fMRI experiments, in conjunction with a meta-analysis of the previous neuroimaging literature, support the claim that an ERP effect classically observed in response to contextual manipulations—the N400 effect—reflects facilitation in processing due to lexical- semantic predictions, and that these predictions are realized at least in part through top-down changes in activity in left posterior middle temporal cortex, the cortical region thought to represent lexical-semantic information in long-term memory. The second part of the dissertation focuses on syntactic predictions. ERP and reaction time data suggest that the syntactic requirements of the prior context impacts processing of the current input very early, and that predicting the syntactic position in which the requirements can be fulfilled may allow the processor to avoid a retrieval mechanism that is prone to similarity-based interference errors. In sum, the results described here are consistent with the hypothesis that a significant amount of language comprehension takes place in advance of the external input, and suggest future avenues of investigation towards understanding the mechanisms that make this possible.
Lingering effects of disfluent material on the comprehension of garden path sentences
Do we experience garden path effects when a disfluent speaker replaces one verb with another (as in "chosen, uh, I mean selected") and only one of the two yields the garden-path ambiguity?
In two experiments, we tested for lingering effects of verb replacement disﬂuencies on the processing of garden path sentences that exhibit the main verb/reduced relative (MV/RR) ambiguity. Participants heard sentences with revisions like "The little girl chosen, uh, selected for the role celebrated with her parents and friends." We found that the syntactic ambiguity associated with the reparandum verb involved in the disﬂuency (here "chosen") had an inﬂuence on later parsing: Garden path sentences that included such revisions were more likely to be judged grammatical if the reparandum verb was structurally unambiguous. Conversely, ambiguous non-garden path sentences were more likely to be judged ungrammatical if the structurally unambiguous disﬂuency verb was inconsistent with the ﬁnal reading. Results support a model of disﬂuency processing in which the syntactic frame associated with the replacement verb ‘‘overlays’’ the previous verb’s structure rather than actively deleting the already-built tree.