Daily Eastern News: April 30, 1990

https://thekeep.eiu.edu/den_1990_apr/1020/thumbnail.jp

Towards a Computational Model of Actor-Based Language Comprehension

Neurophysiological data from a range of typologically diverse languages provide evidence for a cross-linguistically valid, actor-based strategy of understanding sentence-level meaning. This strategy seeks to identify the participant primarily responsible for the state of affairs (the actor) as quickly and unambiguously as possible, thus resulting in competition for the actor role when there are multiple candidates. Due to its applicability across languages with vastly different characteristics, we have proposed that the actor strategy may derive from more basic cognitive or neurobiological organizational principles, though it is also shaped by distributional properties of the linguistic input (e.g. the morphosyntactic coding strategies for actors in a given language). Here, we describe an initial computational model of the actor strategy and how it interacts with language-specific properties. Specifically, we contrast two distance metrics derived from the output of the computational model (one weighted and one unweighted) as potential measures of the degree of competition for actorhood by testing how well they predict modulations of electrophysiological activity engendered by language processing. To this end, we present an EEG study on word order processing in German and use linear mixed-effects models to assess the effect of the various distance metrics. Our results show that a weighted metric, which takes into account the weighting of an actor-identifying feature in the language under consideration outperforms an unweighted distance measure. We conclude that actor competition effects cannot be reduced to feature overlap between multiple sentence participants and thereby to the notion of similarity-based interference, which is prominent in current memory-based models of language processing. Finally, we argue that, in addition to illuminating the underlying neurocognitive mechanisms of actor competition, the present model can form the basis for a more comprehensive, neurobiologically plausible computational model of constructing sentence-level meaning

Processing linguistic complexity and grammaticality in the left frontal cortex

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Focused-attention meditation increases cognitive control during motor sequence performance: Evidence from the N2 cortical evoked potential

Previous work found that single-session focused attention meditation (FAM) enhanced motor sequence learning through increased cognitive control as a mechanistic action, although electrophysiological correlates of sequence learning performance following FAM were not investigated. We measured the persistent frontal N2 event-related potential (ERP) that is closely related to cognitive control processes and its ability to predict behavioural measures. Twenty-nine participants were randomised to one of three conditions reflecting the level of FAM experienced prior to a serial reaction time task (SRTT): 21 sessions of FAM (FAM21, N = 12), a single FAM session (FAM1, N = 9) or no preceding FAM control (Control, N = 8). Continuous 64-channel EEG were recorded during SRTT and N2 amplitudes for correct trials were extracted. Component amplitude, regions of interests, and behavioural outcomes were compared using mixed effects regression models between groups. FAM21 exhibited faster reaction time performances in majority of the learning blocks compared to FAM1 and Control. FAM21 also demonstrated a significantly more pronounced N2 over majority of anterior and central regions of interests during SRTT compared to the other groups. When N2 amplitudes were modelled against general learning performance, FAM21 showed the greatest rate of amplitude decline over anterior and central regions. The combined results suggest that FAM training provided greater cognitive control enhancement for improved general performance, and less pronounced effects for sequence-specific learning performance compared to the other groups. Importantly, FAM training facilitates dynamic modulation of cognitive control: lower levels of general learning performance was supported by greater levels of activation, whilst higher levels of general learning exhibited less activation

"And yet it moves" or why grammar overrides frequency: A reply to Kempen and Harbusch

We show that Kempen and Harbusch's (Cognition (2003) this issue) arguments against our claims cannot be upheld. On the one hand, their alternative account of our data that is based on the availability of constructions with object-experiencer verbs is not compatible with the literature on the processing of these types of sentences in German. Moreover, their allegation that we failed to conduct an accurate corpus count is simply a misreading of our paper. Insofar, the commentary in no way casts doubt on our claim that grammatical regularities override frequency during online comprehension

Separating syntactic memory costs and syntactic integration costs during parsing: The processing of German WH-questions

Event-related brain potentials (ERPs) were recorded while participants processed case-unambiguous German subject and object WH-questions with either a long or a short distance between the WH-filler and its gap. A sustained left anterior negativity was observed for object questions with long filler-gap distance but not for short object questions. This negativity was modulated by individual differences in working memory capacity. No comparable negativity was elicited by WHETHER-questions which did not contain a filler-gap dependency. A positive-going ERP effect was observed for short and long object WH-questions at the position of the second noun phrase. We interpret the sustained negativity as reflecting working memory processes required for maintaining the dislocated object in memory. Processing costs associated with integrating the stored element into the phrase structure representation are indicated by the local positivity. These results support the notion of separable syntactic working memory and syntactic integration cost components as causes of processing difficulty in complex sentences

Grammar overrides frequency: Evidence from the online processing of flexible word order

We show that online processing difficulties induced by word order variations in German cannot be attributed to the relative infrequency of the constructions in question, but rather appear to reflect the application of grammatical principles during parsing. Event-related brain potentials revealed that dative-marked objects in the initial position of an embedded sentence do not elicit a neurophysiologically distinct response from subjects, whereas accusative-marked objects do. These differences are predictable on the basis of grammatical distinctions (i.e. underlying linguistic properties), but not on the basis of frequency information (i.e. a superficial linguistic property). We therefore conclude that the former, but not the latter, guides syntactic integration during online parsing

Contextual information modulates initial processes of syntactic integration: the role of inter- versus intrasentential predictions

The authors demonstrate that intersentential context may influence syntactic integration processes during online sentence comprehension, although this influence appears to be restricted to cases in which a contextual requirement must be fulfilled. By applying event-related brain potentials to the processing of clause-medial word order variations in German, the authors show that the local processing difficulty (a negativity from 300 to 450 ms) observed for object-initial sentences in a neutral context is also obtained in a (behaviorally) facilitating context in which the object is contextually given. By contrast, the processing pattern for a focused (questioned) initial object does not differ from that for a focused subject: both elicit a parietal positivity (280-480 ms) post-onset of the focused phrase. The authors interpret this early positivity as a general marker of focus integration, a process that appears to briefly supersede sentence-internal requirements

Beyond syntax: Language-related positivities reflect the revision of hierarchies

On the basis of an experiment using event-related brain potentials (EPRs), we argue that a characterisation of language-related positivities as necessarily syntax-related is too restrictive. Our data show that, in verb-final German clauses, the processing of a verb which disconfirms the expectations with regard to the hierarchical thematic structure of a sentence (who is doing what to whom) gives rise to an early (200-600 ms) parietal positivity. Thus, positive ERP components elicited during language processing appear to be related to operations (most often revisions) applying to hierarchically structured linguistic information in general, rather than to syntactic structure in particular