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Comparing novel visual words learning methods and the impact of consolidation with an original FPVS-EEG approach
Poster D2 in Poster Session D, Saturday, October 26, 10:30 am - 12:00 pm, Great Hall 4
Amaury Barillon1, Christine Schiltz1, Aliette Lochy1,2; 1University of Luxembourg, 2Université catholique de Louvain
Throughout adulthood, we continually learn novel written words that are integrated in neural circuits of our brain. But the impact of phonology, orthography, and semantics in creating the corresponding new neural representations is still unclear. Furthermore, the mandatory role of sleep consolidation is debated. Here, we investigate the emergence of novel neural representations for written words using fast periodic visual stimulation (FPVS) with EEG recordings and lexical decision tasks. We tested 30 adults (19 females; age mean=23.25; range=18-34 years old) before, immediately after and two days after learning 32 rare French words. In the first learning stage, words were learnt with phonological information only (PH), or with additional explicit semantic information (SEM). In the second stage, orthographic information was provided regardless of the method. Novel words were taught by blocs of 8, through different learning tasks (repetition, sentence making, matching, etc…), and were counterbalanced so that they were either learned with PH or SEM method. Each testing session (pre, post, and consolidation) included lexical decision tasks and frequency-tagging (FPVS) with EEG recordings. A written free recall was added in the consolidation session. The FPVS-oddball paradigm measures neural word-selective responses by displaying pseudowords at 10 Hz, with deviant words every 5 stimuli (2Hz). Responses to deviant stimuli at 2Hz indicate that words have been automatically discriminated from pseudowords and hence, lexical discrimination. We contrasted 4 sequence types displaying words (learned words with PH, learned words with SEM, unknown words, and known words) among respectively matched pseudowords. Every condition was repeated 4 times for a total of 16 sequences of 60 seconds. EEG results show a significant learning effect, with increased amplitudes at post-test for word-selective responses over the left occipital-temporal cortex with both learning methods, while no response was observed at pre-test. Moreover, this effect persists over time, showing no difference between post and consolidation sessions, while a significant difference is observed between pre and consolidation sessions with both methods. Lexical decision tasks show better recognition (accuracy) of the novel words at post and consolidation sessions, and an increase in reaction times for novel words’ orthographic neighbors, and for 1-letter close pseudo-words with both methods at post and consolidation testing, suggesting immediate competition with new lexicalizations. No differences between methods were found in neural responses assessed with FPVS-EEG, or in behavioral lexical decision results. However, the free recall task indicated a clear advantage for words learned with the semantic method (50% vs 38% recall). In conclusion, our findings provide new evidence for the emergence of immediate new lexicalization for novel words after a short learning period, that persists over time. Also, when comparing methods, our study highlights a divergence between results as a function of the task as we demonstrated a clear semantic advantage only when the task was sufficiently challenging. In other words, novel words are well encoded with both methods, but their retrieval is facilitated when novel words are learnt with a semantic method.
Topic Areas: Reading, Meaning: Lexical Semantics