Parametric effects of syntactic-semantic conflict in Broca's area during sentence processing

The hypothesized role of Broca’s area in sentence processing ranges from domain-general executive function to domain-specific computation that is specific to certain syntactic structures. We examined this issue by manipulating syntactic structure and conflict between syntactic and semantic cues in a sentence processing task. Functional neuroimaging revealed that activation within several Broca’s area regions of interest reflected the parametric variation in syntactic-semantic conflict. These results suggest that Broca’s area supports sentence processing by mediating between multiple incompatible constraints on sentence interpretation, consistent with this area’s well-known role in conflict resolution in other linguistic and non-linguistic tasks.     

BOLD response to semantic and syntactic processing during hypoglycemia is load-dependent

This study investigates how syntactic and semantic load factors impact sentence comprehension and BOLD signal under moderate hypoglycemia. A dual session, whole brain fMRI study was conducted on 16 healthy participants using the glucose clamp technique. In one session, they experienced insulin-induced hypoglycemia (plasma glucose at ∼50 mg/dL); in the other, plasma glucose was maintained at euglycemic levels (∼100 mg/dL). During scans subjects were presented with sentences of contrasting syntactic (embedding vs. conjunction) and semantic (reversibility vs. irreversibility) load. Semantic factors dominated the overall load effects on both performance (p < 0.001) and BOLD response (p < 0.01, corrected). Differential BOLD signal was observed in frontal, temporal, temporo-parietal and medio-temporal regions. Hypoglycemia and syntactic factors significantly impacted performance (p = 0.002) and BOLD response (p < 0.01, corrected) in the reversible clause conditions, more extensively in reversible-embedded than in reversible-conjoined clauses. Hypoglycemia resulted in a robust decrease in performance on reversible clauses and exerted attenuating effects on BOLD unselectively across cortical circuits.The dominance of reversibility in all measures underscores the distinction between the syntactic and semantic contrasts. The syntactic is based in a quantitative difference in algorithms interpreting embedded and conjoined structures. We suggest that the semantic is based in a qualitative difference between algorithmic mapping of arguments in reversible clauses and heuristic linking in irreversible clauses. Because heuristics drastically reduce resource demand, the operations they support would resist the load-dependent cognitive consequences of hypoglycemia.     

Big brown dog or brown big dog? An electrophysiological study of semantic constraints on prenominal adjective order

Event-related brain potentials (ERPs) were recorded while participants read and made acceptability judgments about sentences containing three types of adjective sequences: (1) normal sequences--e.g., Jennifer rode a huge gray elephant; (2) reversed sequences that violate grammatical-semantic constraints on linear order--e.g., *Jennifer rode a gray huge elephant; and (3) contradictory sequences that violate lexical-semantic constraints on compositionality--e.g., *Jennifer rode a small huge elephant. Relative to the control condition, the second adjective elicited a reduced N400 and an enhanced P600 in both the reversal condition and the contradiction condition. We present several alternative accounts of these two effects, but favor an interpretation which treats them as reflecting semantic and syntactic aspects of a temporary reanalysis of the adjective order construction. Furthermore, relative to the control condition, the final noun elicited a robust N400 in the contradiction condition but not in the reversal condition. We suggest that this effect indexes the full registration of the lexical-semantic incompatibility of the two adjectives in the contradiction condition. Finally, we discuss how all of these findings fit into the broader context of recent ERP studies that have reported atypical N400s and robust P600s in response to certain types of semantic anomalies.     

A probabilistic model of semantic plausibility in sentence processing

Experimental research shows that human sentence processing uses information from different levels of linguistic analysis, for example, lexical and syntactic preferences as well as semantic plausibility. Existing computational models of human sentence processing, however, have focused primarily on lexico-syntactic factors. Those models that do account for semantic plausibility effects lack a general model of human plausibility intuitions at the sentence level. Within a probabilistic framework, we propose a wide-coverage model that both assigns thematic roles to verb–argument pairs and determines a preferred interpretation by evaluating the plausibility of the resulting ( verb , role , argument ) triples. The model is trained on a corpus of role-annotated language data. We also present a transparent integration of the semantic model with an incremental probabilistic parser. We demonstrate that both the semantic plausibility model and the combined syntax/semantics model predict judgment and reading time data from the experimental literature.     

Shadows of music-language interaction on low frequency brain oscillatory patterns

Electrophysiological studies investigating similarities between music and language perception have relied exclusively on the signal averaging technique, which does not adequately represent oscillatory aspects of electrical brain activity that are relevant for higher cognition. The current study investigated the patterns of brain oscillations during simultaneous processing of music and language using visually presented sentences and auditorily presented chord sequences. Music-syntactically regular or irregular chord functions were presented in sync with syntactically or semantically correct or incorrect words. Irregular chord functions (presented simultaneously with a syntactically correct word) produced an early (150-250 ms) spectral power decrease over anterior frontal regions in the theta band (5-7 Hz) and a late (350-700 ms) power increase in both the delta and the theta band (2-7 Hz) over parietal regions. Syntactically incorrect words (presented simultaneously with a regular chord) elicited a similar late power increase in delta-theta band over parietal sites, but no early effect. Interestingly, the late effect was significantly diminished when the language-syntactic and music-syntactic irregularities occurred at the same time. Further, the presence of a semantic violation occurring simultaneously with regular chords produced a significant increase in later delta-theta power at posterior regions; this effect was marginally decreased when the identical semantic violation occurred simultaneously with a music syntactical violation. Altogether, these results show that low frequency oscillatory networks get activated during the syntactic processing of both music and language, and further, these networks may possibly be shared.     

Syntactic structure building in the anterior temporal lobe during natural story listening

The neural basis of syntax is a matter of substantial debate. In particular, the inferior frontal gyrus (IFG), or Broca’s area, has been prominently linked to syntactic processing, but the anterior temporal lobe has been reported to be activated instead of IFG when manipulating the presence of syntactic structure. These findings are difficult to reconcile because they rely on different laboratory tasks which tap into distinct computations, and may only indirectly relate to natural sentence processing. Here we assessed neural correlates of syntactic structure building in natural language comprehension, free from artificial task demands. Subjects passively listened to Alice in Wonderland during functional magnetic resonance imaging and we correlated brain activity with a word-by-word measure of the amount syntactic structure analyzed. Syntactic structure building correlated with activity in the left anterior temporal lobe, but there was no evidence for a correlation between syntactic structure building and activity in inferior frontal areas. Our results suggest that the anterior temporal lobe computes syntactic structure under natural conditions.     

Poverty of the stimulus revisited

A central goal of modern generative grammar has been to discover invariant properties of human languages that reflect "the innate schematism of mind that is applied to the data of experience" and that "might reasonably be attributed to the organism itself as its contribution to the task of the acquisition of knowledge" (Chomsky, 1971). Candidates for such invariances include the structure dependence of grammatical rules, and in particular, certain constraints on question formation. Various "poverty of stimulus" (POS) arguments suggest that these invariances reflect an innate human endowment, as opposed to common experience: Such experience warrants selection of the grammars acquired only if humans assume, a priori, that selectable grammars respect substantive constraints. Recently, several researchers have tried to rebut these POS arguments. In response, we illustrate why POS arguments remain an important source of support for appeal to a priori structure-dependent constraints on the grammars that humans naturally acquire.     

Learning harmony: the role of serial statistics

How do listeners learn about the statistical regularities underlying musical harmony? In traditional Western music, certain chords predict the occurrence of other chords: Given a particular chord, not all chords are equally likely to follow. In Experiments 1 and 2, we investigated whether adults make use of statistical information when learning new musical structures. Listeners were exposed to a novel musical system containing phrases generated using an artificial grammar. This new system contained statistical structure quite different from Western tonal music. Our results suggest that learners take advantage of the statistical patterning of chords to acquire new musical structures, similar to learning processes previously observed for language learning.     

The privileging of ‘Support-From-Below’ in early spatial language acquisition

Spatial terms that encode support (e.g., “on”, in English) are among the first to be understood by children across languages (e.g., Bloom, 1973; Johnston & Slobin, 1979). Such terms apply to a wide variety of support configurations, including Support-From-Below (SFB; cup on table) and Mechanical Support, such as stamps on envelopes, coats on hooks, etc. Research has yet to delineate infants’ semantic space for the term “on” when considering its full range of usage. Do infants initially map “on” to a very broad, highly abstract category – one including cups on tables, stamps on envelopes, etc.? Or do infants begin with a much more restricted interpretation - mapping “on” to certain configurations over others? Much infant cognition research suggests that SFB is an event category that infants learn about early - by five months of age (Baillargeon & DeJong, 2017) - raising the possibility that they may also begin by interpreting the word “on” as referring to configurations like cups on tables, rather than stamps on envelopes. Further, studies examining language production suggests that children and adults map the basic locative expression (BE on, in English) to SFB over Mechanical Support (Landau et al., 2016). We tested the hypothesis that this ‘privileging’ of SFB in early infant cognition and child and adult language also characterizes infants’ language comprehension. Using the Intermodal-Preferential-Looking-Paradigm in combination with infant eye-tracking, 20-month-olds were presented with two support configurations: SFB and Mechanical, Support-Via-Adhesion (henceforth, SVA). Infants preferentially mapped “is on” to SFB (rather than SVA) suggesting that infants differentiate between two quite different kinds of support configurations when mapping spatial language to these two configurations and more so, that SFB is privileged in early language understanding of the English spatial term “on”.     

Language, thought, and real nouns

We test the claim that acquiring a mass-count language, like English, causes speakers to think differently about entities in the world, relative to speakers of classifier languages like Japanese. We use three tasks to assess this claim: object-substance rating, quantity judgment, and word extension. Using the first two tasks, we present evidence that learning mass-count syntax has little effect on the interpretation of familiar nouns between Japanese and English, and that speakers of these languages do not divide up referents differently along an individuation continuum, as claimed in some previous reports [Gentner, D., & Boroditsky, L. (2001). Individuation, relativity, and early word learning. In M. Bowerman, & S. Levinson (Eds.), Language acquisition and conceptual development (pp. 215-256). Cambridge University Press]. Instead, we argue that previous cross-linguistic differences [Imai, M., & Gentner, D. (1997). A cross-linguistic study of early word meaning: Universal ontology and linguistic influence. Cognition, 62, 169-200] are attributable to “lexical statistics” [Gleitman, L., & Papafragou, A. (2005). Language and thought. In K. Holyoak, & R. Morrison (Eds.), Cambridge handbook of thinking and reasoning (pp. 633-661). Cambridge University Press]. Speakers of English are more likely to think that a novel ambiguous expression like “the blicket” refers to a kind of object (relative to speakers of Japanese) because speakers of English are likely to assume that “blicket” is a count noun rather than a mass noun, based on the relative frequency of each kind of word in English. This is confirmed by testing Mandarin-English bilinguals with a word extension task. We find that bilinguals tested in English with mass-count ambiguous syntax extend novel words like English monolinguals (and assume that a word like “blicket” refers to a kind of object). In contrast, bilinguals tested in Mandarin are significantly more likely to extend novel words by material. Thus, online lexical statistics, rather than non-linguistic thought, mediate cross-linguistic differences in word extension. We suggest that speakers of Mandarin, English, and Japanese draw on a universal set of lexical meanings, and that mass-count syntax allows speakers of English to select among these meanings.     

Syntax and serial recall: How language supports short-term memory for order

The extent to which familiar syntax supports short-term serial recall of visually presented six-item sequences was shown by the superior recall of lists in which item pairs appeared in the order of “adjective–noun” (items 1–2, 3–4, 5–6)—congruent with English syntax—compared to when the order of items within pairs was reversed. The findings complement other evidence suggesting that short-term memory is an assemblage of language processing and production processes more than it is a bespoke short-term memory storage system.     

The P600 as an indicator of syntactic ambiguity

In a study using event-related brain potentials, we show that the current characterization of the P600 component as an indicator of revision processes (reanalysis and repair) in sentence comprehension must be extended to include the recognition of syntactic ambiguity. By comparing the processing of ambiguous and unambiguous sentence constituents in German, we show that the P600 is elicited when our language processing system has syntactic alternatives at a certain item given in the input string. That the P600 is sensitive to syntactic ambiguity adds crucial evidence to current debates in psycholinguistic modelling, as the results clearly favour parallel models of syntactic processing which assume that ambiguity is recognized and costly.