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"Waves of learning new words": The neural dynamics of cross-situational word learning
Poster Session B, Friday, October 25, 10:00 - 11:30 am, Great Hall 3 and 4
Samuel Armstrong1, Paola Escudero2, Anthony Angwin1; 1University of Queensland, 2Western Sydney University
Cross-situational word learning describes the process by which individuals learn new words by tracking and integrating statistical co-occurrences between words and their potential referents across various contexts and time points. In this study, we investigated the neural oscillatory mechanisms underlying the acquisition of written word meanings via cross-situational learning of novel names for familiar objects. Continuous scalp-EEG was recorded from healthy young adult participants (N=19) as they completed a cross-situational word learning task (encoding phase) followed by a semantic relatedness judgment task (recognition phase). During the encoding phase, participants learned meanings of novel written words from repeated encounters with different word-referent correspondences, presented across multiple contexts and timepoints. Repeated encoding encounters led to a build-up in statistical regularities and the gradual disambiguation of correct word-referent co-pairings, subsequently facilitating the formation of new word-object meaning associations. Importantly, participants received no explicit learning instructions nor were they informed of the word learning nature of the experiment; they were simply asked to maintain their gaze on the computer screen. After learning associations between novel written words (e.g., shope) and familiar object pictures (e.g., apple), participants completed a semantic judgment task where learned novel words were paired with familiar written words belonging to either the same (e.g., pear) or a different (e.g., sword) semantic category. For comparison, related and unrelated familiar word pairs were also included in the semantic judgment task. To measure changes in oscillatory responses, we conducted time-frequency analysis to obtain event-related spectral perturbations for novel written words, separately for encoding and recognition tasks. We observed modulations in oscillatory power across multiple frequency bands from 3-50 Hz during both tasks. Notably, there was greater enhancement of theta and low-gamma responses during cross-situational word learning, with gamma showing greater synchronization over left-hemisphere language regions. During the recognition task, theta oscillations exhibited greater power for semantic judgments of related versus unrelated word meanings, with more pronounced enhancements over the left hemisphere. Additionally, greater alpha and beta desynchronization was observed during both encoding and recognition tasks. Our findings are the first to report the oscillatory dynamics underlying cross-situational learning. More interestingly, these oscillatory responses reflect the neural mechanisms involved in the incremental and statistical nature of word learning, providing insight into the temporal and spatial characteristics of neural processes that support the formation and retrieval of novel word meanings.
Topic Areas: Language Development/Acquisition, Meaning: Lexical Semantics