Poster A47, Saturday, March 24, 1:30–3:30 pm, Exhibit Hall C
Violations of ASL Sentence Processing: Observed Changes in Neural Oscillations
Tristan Schaefer1, Kristina Backer1, Michael Grosvald2, David P. Corina1; 1Center for Mind and Brain, University of California, Davis, 2Qatar University
There is interest in characterizing neural oscillatory activity associated with language processing. To date, the majority of studies have focused on changes observed during the processing of spoken languages. Here, we describe results from a time-frequency analysis of EEG data from deaf signers processing American Sign Language (ASL). Using data from Grosvald et al., (2012), we examined oscillatory power changes as signers (n = 20) watched videos of ASL sentences that ended in one of four possible conditions; semantically congruent, semantically incongruent, pseudo-signs, or a non-linguistic gesture (e.g. rubbing one’s eye). Thirty-two channel EEG data was analyzed, and power estimates of neural oscillations were computed using the FieldTrip toolbox. In line with previous research on lexical and sentential violations (e.g. Strauss et al 2015; Bastiaansen et al., 2010), we examined changes in power changes in theta (3-7 Hz), alpha (8-12 Hz), and high beta (19-25 Hz) ranges. We observed significant power differences in a temporal window between 400-1000 ms. after the critical sign/gesture in posterior channels (Pz, P3, P4, O1, O2, Oz). Relative to semantically congruent signs, significant increases in theta power were observed for pseudo-signs (p < .03) and self-grooming gestures (p < .04). In contrast, significant decreases in high beta power were observed only for self-grooming gesture relative to semantically congruent signs (p < .006). The data suggest theta enhancement may be related to early stages of lexical ambiguity, while changes in beta frequency may index interruption of the cognitive state by unexpected stimuli (Engel and Fries, 2010).
Topic Area: LANGUAGE: Other