Neural Basis of Semantic Constraints on Adjective Order

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DESCRIPTION (provided by applicant): People have strong intuitions about the grammaticality of adjective sequences that precede nouns - e.g., pretty brown bird sounds natural, but *brown pretty bird sounds odd. These intuitions reflect semantic constraints on adjective order that apply not just in English but in many diverse languages around the world. Specifically, adjectives that denote objective, absolute, inherent properties of entities (like brown) usually occur closer to the noun than adjectives that denote subjective, relativistic, context-sensitive properties (like pretty). Adjective order is one manifestation of 'grammatical semantics,' the technical term for a small set of semantic features that tend to interact closely with the morphosyntax of languages. Linguists have proposed that grammatically relevant and grammatically irrelevant components of meaning are mentally represented independently of each other, and this psychological hypothesis has a neurobiological corollary, which is that the two components of meaning also have distinct neural substrates. However, very little work in cognitive neuroscience has addressed this topic. The goal of this project is to explore the neural basis of grammatical semantics by investigating adjective order from the perspectives of neuropsychology, neuroanatomy, and electrophysiology. There are three specific aims. Aim 1 is to test the hypothesis that focal brain damage can cause the following type of dissociation: impaired knowledge of the semantic constraints on adjective order, but intact knowledge of the unique, idiosyncratic meanings of adjectives. Patients with this dissociation would no longer be able to judge pretty brown bird as sounding more natural than *brown pretty bird, but would still be able to match pretty and brown with appropriate pictures showing the meanings of the adjectives. Aim 2 is to determine whether there is a brain area that is lesioned in patients with impaired knowledge of the semantic constraints on adjective order, and preserved in patients with normal knowledge of these constraints. Finally, Aim 3 is to identify the kind of electrophysiological response that is triggered by perceived violations of the semantic constraints on adjective order. This will be done by recording event-related potentials in normal adults while they read examples of natural and unnatural adjective orders.