Handwriting decoding as a challenging motor task for EEG Foundation Models

Fuente: arXiv
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Main Authors: Ravishankar, Srinivas, Ghosh, Ishayu, Zajzon, Nora, Fei, Teng, de Sa, Virginia
Format: Preprint
Published: 2026
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author Ravishankar, Srinivas
Ghosh, Ishayu
Zajzon, Nora
Fei, Teng
de Sa, Virginia
author_facet Ravishankar, Srinivas
Ghosh, Ishayu
Zajzon, Nora
Fei, Teng
de Sa, Virginia
contents Recent attempts at creating Foundation Models (FMs) for Electroencephalography (EEG) have achieved state-of-the-art performance on multiple tasks including Motor Imagery (MI). These MI tasks have typically involved coarse classification between imagined limb movements. However, the development of foundation models necessitates diverse datasets, both for pretraining and evaluating the progress of these models. In this work, we propose handwriting decoding as a challenging motor task for FMs. We show that several existing datasets are potentially confounded, and introduce a dataset that more rigorously evaluates models. On this dataset, we find that current FMs, despite showing SOTA performance in multiple MI datasets are outperformed by smaller task-specific models. We also highlight challenges specific to EEG-based handwriting decoding to inform future work. In our 4-letter classification task, we show that (a) Knowledge of movement-onset is crucial to reported decoding performance in prior works, with average performance across subjects dropping from $41.3\%$ to $32.4\%$. (b) Increasing test-time signal quality provides significant performance improvements ($45\%$ to $78\%$ in our best subject) compared to scaling training data with single-trial EEG. (c) While scaling training data steadily improves decoding performance, existing FMs do not outperform specialist models in handwriting decoding. We make our code available at https://anonymous.4open.science/r/EEG-Handwriting-BCI-DFCD/
format Preprint
id arxiv_https___arxiv_org_abs_2605_15698
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Handwriting decoding as a challenging motor task for EEG Foundation Models
Ravishankar, Srinivas
Ghosh, Ishayu
Zajzon, Nora
Fei, Teng
de Sa, Virginia
Human-Computer Interaction
Recent attempts at creating Foundation Models (FMs) for Electroencephalography (EEG) have achieved state-of-the-art performance on multiple tasks including Motor Imagery (MI). These MI tasks have typically involved coarse classification between imagined limb movements. However, the development of foundation models necessitates diverse datasets, both for pretraining and evaluating the progress of these models. In this work, we propose handwriting decoding as a challenging motor task for FMs. We show that several existing datasets are potentially confounded, and introduce a dataset that more rigorously evaluates models. On this dataset, we find that current FMs, despite showing SOTA performance in multiple MI datasets are outperformed by smaller task-specific models. We also highlight challenges specific to EEG-based handwriting decoding to inform future work. In our 4-letter classification task, we show that (a) Knowledge of movement-onset is crucial to reported decoding performance in prior works, with average performance across subjects dropping from $41.3\%$ to $32.4\%$. (b) Increasing test-time signal quality provides significant performance improvements ($45\%$ to $78\%$ in our best subject) compared to scaling training data with single-trial EEG. (c) While scaling training data steadily improves decoding performance, existing FMs do not outperform specialist models in handwriting decoding. We make our code available at https://anonymous.4open.science/r/EEG-Handwriting-BCI-DFCD/
title Handwriting decoding as a challenging motor task for EEG Foundation Models
topic Human-Computer Interaction
url https://arxiv.org/abs/2605.15698