Schedule of Events | Symposia

Time-resolved EEG decoding of neural text representations during naturalistic braille reading

Poster Session F - Tuesday, April 1, 2025, 8:00 – 10:00 am EDT, Back Bay Ballroom/Republic Ballroom

Pushpita Bhattacharyya¹ (pushpita@ski.org), Ryan Tam, Peter Orsmond, Sadie Hicks, Santani Teng; ¹Smith-Kettlewell Eye Research Institute

Braille is a tactile writing system using raised dots to represent text. Blind and visually impaired people read braille by sweeping their fingers across the page, dynamically assembling dot patterns into meaningful text. Understanding braille sensorimotor dynamics has been limited in part by the difficulty of recording time-resolved neural signals during active braille reading, where stimulus onsets are participant-driven. To address this challenge, we implemented a novel approach integrating electromagnetic finger-tracking with EEG to capture dynamic neural representations during naturalistic braille reading. Blind braille readers read a randomized grid of alphabetic letters with one finger, responding verbally to vowels; sighted participants simply moved their finger along the letters. We estimated letter contact timestamps from the position tracker and synced them to the EEG recording to extract stimulus-onset epochs. These were decoded between letters using SVM classification to produce decoding accuracy curves between -200 ms and 1000 ms of stimulus onset. In the blind group, we found a sustained average decoding signal starting ~200 ms after letter onset, peaking ~400 ms (~59% accuracy), and ~280 ms when excluding vowel response conditions (~56% accuracy). Sighted controls showed a similar, weaker average signal, peaking at ~300 ms (~55% accuracy), suggesting shared low-level sensory representations across groups regardless of braille literacy or visual ability, with stronger decoding signals in braille-literate individuals possibly reflecting additionally encoded graphemic representations. Corroborating recent work decoding statically presented braille letters, these results establish the promise of our approach to capture multiplexed linguistic representations during naturalistic, continuous braille processing.

Topic Area: PERCEPTION & ACTION: Other