Computational Psycholinguistics

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Event-related Brain Potentials in Language Processing

Event-related Brain Potentials (ERP) are commonly regarded to be tiny impulse responses in the electroencephalogram (EEG) generated by neural networks that are time-locked to the perception or processing of stimuli and blended by the spontaneous EEG that reflects the ongoing, continuous activity of the brain. In language processing, unexpected sentence continuations, such as semantic anomalies or syntactic garden paths, elicit characteristic ERP responses, such as the N400 and P600 for semantic and syntactic processing problems, respectively (REFREFREFREFREF).

The plot shows ERP waves obtained from the Symbolic Resonance Analysis (SRA) at a posterior electode site for processing unlicensed negative polarity items. The SRA reveals an early and a late subcomponent of the reanalysis P600 that are not observable by means of voltage averages (REF). Computational Psycholinguistics

Nonlinear Dynamical Automata

Transients in symbolic dynamics represent computational processes. We have utilized this finding for the construction of (context-free) grammar recognizers as Nonlinear Dynamical Automata (REFREF). The corresponding phase space representation allows for determining processing costs such as parsing entropy which has been related to language processing ERPs. We have described processes of diagnosis and reanalysis by a bifurcation-like tuning of the system’s control parameter. Additionally, the autonomous parsing dynamics has been augmented by an interactive counterpart (REFREF).

The Figure shows the temporal evolution of parsing states (from top to bottom) for an interactive NDA with diagnosis and repair steps (indicated by “*”). One  interaction where a new input is scanned from the environment into working memory is indicated by “o” (REF).

You may see an NDA animation by clicking at the image.Computational Psycholinguistics

Pragmatic Information Theory

The concept of “pragmatic information” has been introduced by stating three desiderata: i) Pragmatic information assesses the impact of a message upon its receiver. ii) In the limits of non-interpretable “novelty” and complete “confirmation”, the pragmatic information vanishes. iii) Novelty and confirmation behave as Fourier-pairs of complementary operators in quantum mechanics; pragmatic information should hence exhibit some non-classical properties. We have shown how these requirements can be naturally fulfilled within the framework of the dynamic semantics of Bayesian belief models (REF).

The Figure illustrates the property ii) above, the non-monotonic dependence of pragmatic information on novelty (randomness) and confirmation. This is also characteristic for measures of complexity (REF).Pragmatic Information Theory

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