Processing of verbal aspect in Croatian Sign Language: an EEG study with native bimodal bilingual signers

Sign languages, as natural languages in the visual modality, offer unique insights into the neurocognitive mechanisms of language processing, particularly in prediction and event representation. This study investigates the neural processing of perceptual and linguistic features of event marking in Croatian Sign Language (HZJ) among bimodal bilingual users. Verbal aspect, a key component of event structure, is encoded in HZJ through systematic phonological alternations that differentiate perfective and imperfective forms (Malaia et al., 2013). These alternations are further constrained by adverbs (e.g., "already" for perfective, "still" for imperfective). While ERP studies have identified the N400 and P600 components in response to semantic and morphosyntactic violations in sign languages, the impact of aspectual congruence at the syntax-semantics interface remains unexplored (Radošević et al., 2022). This study hypothesizes that congruence between adverbs and verbs in HZJ will elicit differential ERP responses. Specifically, semantic mismatches are expected to evoke an N400 effect, while morphosyntactic incongruence will trigger a P600 effect, reflecting reanalysis processes.
Twenty native hearing bimodal bilinguals participated in the study. EEG data were recorded using a 32-channel system while participants viewed sentences containing aspectual adverbs followed by perfective or imperfective verbs. This 2x2 design manipulated adverb-verb congruence. Participants judged whether the described event was ongoing or completed, providing behavioral data on aspectual processing. The analysis will focus on ERP components commonly associated with linguistic prediction and integration: the N400, reflecting semantic processing, and the P600, indicative of morphosyntactic reanalysis. Congruent sentences are expected to produce smaller amplitudes in these components compared to incongruent ones, reflecting easier integration and reduced processing costs.
This study aims to uncover how aspectual congruence is processed in real time and to what extent predictive mechanisms operate at the syntax-semantics interface in HZJ. The findings will contribute to our understanding of temporal processing in sign languages and the broader neurocognitive mechanisms underlying language comprehension across modalities.

References:

Malaia, E., Wilbur, R. B., & Milković, M. (2013). Kinematic parameters of signed verbs. Journal of Speech Language and Hearing Research, 56(5), 1677–1688. https://doi.org/10.1044/1092-4388(2013/12-0257

Radošević, T., Malaia, E. A., & Milković, M. (2022). Predictive processing in sign languages: A systematic review. Frontiers in psychology, 13, 805792.