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Neural sensitivity to ASL phonological structure in deaf signers and hearing L2 learners
Poster Session D, Thursday, October 1, 4:30 - 6:30 pm, Wangari Maathai
Sarah Kimbley1, Katherine Midgley1, Gabriela Meade2, Phillip Holcomb1, Karen Emmorey1; 1SDSU, 2Mayo Clinic
Sign languages such as ASL exhibit phonological structure, including sublexical units such as handshape and location. ERP studies show that deaf signers are sensitive to these properties: handshape overlap between prime and target signs produces facilitation (reduced N400), whereas location overlap produces interference (increased negativity), possibly reflecting lateral inhibition among signs sharing a given location (Meade et al., 2021, 2022). Hearing non-signers do not show these effects in the N400 window but exhibit late sensitivity to location, suggesting location is perceptually salient without sign knowledge (Meade et al., 2022). Previous studies used real sign primes, leaving open whether these effects reflect sublexical pre-activation or lexical-level processes, and whether hearing adults develop sensitivity to phonological structure after acquiring a small sign vocabulary. We addressed both questions using pseudosign primes—composed of real sublexical units but not corresponding to existing signs–paired with real sign targets. We recorded ERPs from deaf signers (N = 23) and hearing participants (N = 20) before and after they learned 92 ASL signs across three training sessions. Stimuli were full-length videos; sign onset occurred ~380 ms after video onset. Participants performed a go/no-go item-repetition detection task (~15% of trials). In related pairs, the pseudosign shared either handshape or location with the target; unrelated pairs shared no parameters. Targets were selected from ASL-LEX (Caselli et al., 2017) with low iconicity and transparency. We analyzed mean amplitude with ANOVAs (Priming × Laterality × Anteriority) across four windows (200–400, 400–600, 600–800, 800–1000 ms). Deaf signers exhibited handshape facilitation at 600–1000 ms (600–800: F(1,22) = 6.22, p = .021; 800–1000: F(1,22) = 8.73, p = .007), with unrelated targets eliciting greater negativity over centro-parietal sites, consistent with sublexical pre-activation of established handshape representations. This replicates Meade et al. (2021, 2022) with pseudosign primes, indicating that handshape facilitation operates at the sublexical level. For location, a trend toward interference emerged at 400–600 ms (p = .072), with significant Priming × Anteriority (p < .001) and Priming × Laterality × Anteriority (p = .002) interactions, reflecting posterior positivity and anterior negativity. Because pseudosigns lack lexical representations, the shared location may activate location-based neighborhoods, producing lateral inhibition at the interface between sublexical and lexical processing. Before learning, hearing non-signers showed no sensitivity to handshape. For location, an early interference effect emerged at 200–400 ms (p = .012), consistent with the perceptual salience of location. Following training, this effect shifted to 400–600 ms and increased in magnitude (F(1,19) = 16.08, p < .001), suggesting that learning enhanced perceptual sensitivity to location. For handshape, a Priming × Laterality interaction (p = .006) at 600–800 ms revealed a left-lateralized facilitation effect, suggesting emerging sensitivity to handshape—a distribution differing from the bilateral facilitation in deaf signers. These findings demonstrate that handshape and location are processed differently. Hearing non-signers showed perceptual sensitivity to location before learning, which was enhanced after training. Handshape sensitivity emerged only post-learning with a left-lateralized distribution, suggesting early-stage linguistic processing. These results indicate that limited ASL learning can shape neural sensitivity to phonological structure.
Topic Areas: Signed Language and Gesture, Phonology