# Brain-Computer Interfaces: State of the Field (October 2026)

Research dossier · v1 · updated 2026-10-30 · 3,721 words · 44 sources · 29 claims · verification: verified

Covers intracortical and cortical-surface speech neuroprostheses, electrode-density and stability work, noninvasive EEG and fNIRS interfaces, stroke-rehabilitation trials, and the open debates on decoder design and imagined-speech validity as of October 2026. The most important takeaway: intracortical speech decoding has reached 62 words per minute with a 9.1% word error rate on a 50-word vocabulary, but error rises sharply with vocabulary size and calibration burden and regulatory status remain unsettled.

## Contents

- Executive summary
- Background and core concepts
- Timeline of key milestones
- State of the art
  - Intracortical speech neuroprostheses
  - Cortical-surface (ECoG) systems
  - Intracortical communication and control
  - Calibration, stability and transfer
  - Noninvasive BCIs and imagined speech
  - Rehabilitation trials
  - Electrode materials, safety and robustness
  - Quantitative benchmarks
- Open problems and active debates
- Major programs and players
- Outlook: what to watch
- Key papers
- Glossary

## Sample findings

- Willett et al. (2023) reported attempted speech decoded into text at 62 words per minute with an intracortical speech neuroprosthesis.
- The same 2023 system had a 9.1% word error rate on a 50-word vocabulary.

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