Poster C32, Wednesday, August 21, 2019, 10:45 am – 12:30 pm, Restaurant Hall
Neural Correlates of Semantic Processing for Abstract Verbs
Emiko Muraki1, Alison Doyle1, Andrea B. Protzner1, Penny M. Pexman1;1University of Calgary
Introduction: It has been well documented that different types of nouns are associated with behavioural and neural differences. In contrast, studies of verbs are less common and have tended to focus on concrete verbs that refer to specific physical actions (e.g., kick, run, etc.) The neural correlates of, and potential distinctions between, abstract verbs (verbs not associated with sensorimotor experience, e.g. think, dissolve, etc.) have yet to be systematically addressed. Although abstract verbs tend to be treated as a homogeneous category, there may be distinct types of abstract verbs. We used EEG recording during a syntactic classification task (SCT) to determine whether modality-based distinctions amongst abstract verb types correspond to different dimensions of underlying semantic representation in their associated brain responses. Methods: We analyzed the data for 36 participants who completed a go/no-go SCT (is it a verb?) during EEG recording. Stimuli for the SCT consisted of four verb types; those that represent 1) abstract mental states, 2) abstract emotional states, 3) abstract, external, non-bodily states, and 4) concrete verbs, in addition to a large set of nouns. A multivariate, data-driven analysis technique, partial least squares (PLS) analysis, was employed to investigate differences in neural activity between the four different verb types. Results: The PLS analysis identified one significant latent variable (p = .009), which highlighted a distinction between the external, non-bodily state verbs compared to the mental state and concrete verbs (emotional words did not contribute to this pattern). Bilateral frontocentral electrodes showed sustained negativity at 400 – 600 ms post-stimulus onset, with larger negative amplitudes for the external, non-bodily state verbs relative to concrete and mental state verbs. This same effect appeared bilaterally as sustained positivity at parietal and occipital electrodes, suggesting centrally located sources. Lastly, the non-bodily state/concrete and mental state verb differentiation was more dominant in anterior electrodes on the left, and posterior electrodes on the right. Discussion: Verbs differ in the modalities referenced by their meanings, and our results suggest that these differences are evident in their neural correlates. The abstract, external state verbs appear most different from concrete and mental state abstract verbs in terms of neural source generators. These findings underscore the idea that abstract verbs are not a homogenous category and that different types of abstract verbs may be associated with representational differences.
Themes: Meaning: Lexical Semantics, Multisensory or Sensorimotor Integration
Method: Electrophysiology (MEG/EEG/ECOG)