Implicit Acquisition of Grammars With Crossed and Nested Non-Adjacent Dependencies: Investigating the Push-Down Stack Model

Authors

  • Julia Uddén,

    1. Max Planck Institute for Psycholinguistics, Nijmegen, The Netherlands
    2. Cognitive Neurophysiology Research Group, Stockholm Brain Institute, Department of Clinical Neuroscience, Karolinska Institute
    3. Donders Institute for Brain, Cognition and Behaviour, Centre for Cognitive Neuroimaging, Radboud University Nijmegen
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  • Martin Ingvar,

    1. Cognitive Neurophysiology Research Group, Stockholm Brain Institute, Department of Clinical Neuroscience, Karolinska Institute
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  • Peter Hagoort,

    1. Max Planck Institute for Psycholinguistics, Nijmegen, The Netherlands
    2. Donders Institute for Brain, Cognition and Behaviour, Centre for Cognitive Neuroimaging, Radboud University Nijmegen
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  • Karl M. Petersson

    1. Max Planck Institute for Psycholinguistics, Nijmegen, The Netherlands
    2. Cognitive Neurophysiology Research Group, Stockholm Brain Institute, Department of Clinical Neuroscience, Karolinska Institute
    3. Donders Institute for Brain, Cognition and Behaviour, Centre for Cognitive Neuroimaging, Radboud University Nijmegen
    4. Cognitive Neuroscience Research Group, Institute of Biotechnology & Bioengineering, Centre for Molecular and Structural Biomedicine, University of the Algarve
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should be sent to Julia Uddén, Stockholm Brain Institute, A2:3, Retzius väg 8, 171 72 Stockholm, Sweden. E-mail: julia.udden@ki.se

Abstract

A recent hypothesis in empirical brain research on language is that the fundamental difference between animal and human communication systems is captured by the distinction between finite-state and more complex phrase-structure grammars, such as context-free and context-sensitive grammars. However, the relevance of this distinction for the study of language as a neurobiological system has been questioned and it has been suggested that a more relevant and partly analogous distinction is that between non-adjacent and adjacent dependencies. Online memory resources are central to the processing of non-adjacent dependencies as information has to be maintained across intervening material. One proposal is that an external memory device in the form of a limited push-down stack is used to process non-adjacent dependencies. We tested this hypothesis in an artificial grammar learning paradigm where subjects acquired non-adjacent dependencies implicitly. Generally, we found no qualitative differences between the acquisition of non-adjacent dependencies and adjacent dependencies. This suggests that although the acquisition of non-adjacent dependencies requires more exposure to the acquisition material, it utilizes the same mechanisms used for acquiring adjacent dependencies. We challenge the push-down stack model further by testing its processing predictions for nested and crossed multiple non-adjacent dependencies. The push-down stack model is partly supported by the results, and we suggest that stack-like properties are some among many natural properties characterizing the underlying neurophysiological mechanisms that implement the online memory resources used in language and structured sequence processing.

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