Poster C25, Friday, August 17, 10:30 am – 12:15 pm, Room 2000AB
Lower Beta Suppression during Early Verb Learning
Emma K. Tharp1, Yvonne Ralph1, Julie M. Schneider1, Mandy J. Maguire1;1University of Texas at Dallas
Introduction: Processing language requires activation and integration of sensorimotor and semantic features. For example, reading text that contains action sentences (Elk, M. Van, et al., 2010) and/or action verbs (Maguire et al. 2015; Middleton, Schneider & Maguire, 2017) often results in suppression of the beta band activity. This suppression is similar to what is observed when performing or viewing others perform actions (Weiss & Mueller, 2012.) The role of semantic embodiment varies between word classes, but little has been done to investigate this within the context of word learning. Specifically, when learning new verbs using only the surrounding linguistic context, do we observe decreases in beta band activity? To address this question, we compared the changes in neural oscillations that occur when learning new nouns and verbs from linguistic contexts. Methods: Thirty-six right-handed, English speaking college aged adults had their EEG and behavioral responses recorded while performing a word learning task. Stimuli were sentence triplets where the final word of each sentence was a pseudoword that represented a real noun or verb. Each sentence was presented one word at a time on a computer monitor. After the presentation of all sentences within the triplet, participants were asked to name the final word they felt best fit all three sentences. Although this is different from creating a new semantic concept when learning an entirely novel idea, new words are often learned as a nuanced meaning for a concept one already has a name for, anchoring the unknown word’s meaning to a known word, then identifying differences between the known and unknown words’ meanings across exposures (Waxman & Senghas, 1992). This study addresses this first step in word learning. Further, this design ensures that none of the participants knew the words prior to the study. Analysis: EEG data was epoched from 500 msec before to 1500 msec after the target word onset. Only trials in which participants responded to correctly were included in the analysis. Time-Frequency analysis was utilized. The mean ERSP for the lower beta frequency (13-19 Hz) was computed for all data channels and a morlet wavelet was applied to each epoch. The mean baseline power at each electrode and frequency was subtracted. Statistical significance was determined using a monte-carlo permutation analysis similar to that used by Maris and Oostenveld (2007). Results: There was a significant interaction in lower beta between word class and presentation over the posterior region (all p’s < 0.05). Specifically, when learning verbs, compared with nouns, participants exhibited a significant decrease in lower beta between 0-200 msec only on the last (third) presentation. This was not observed in nouns. Conclusion: These findings add to current theories of semantic embodiment by revealing that beta suppression is evident in the early stages of word learning and even when the learners use only linguistic (not visual or motor) cues to learn the word’s meaning. These results have implications for understanding the role of semantic embodiment in word learning.
Topic Area: Meaning: Lexical Semantics