Collaborative (shared) BCI

A collaborative BCI combines brain signals from several users to produce a single command or decision, on the premise that fusing multiple noisy brains beats any one of them — a neural wisdom of crowds. Unlike a BBI, no brain is written to; the users share only an output. Classic demonstrations fuse multiple P300 or SSVEP responses to speed a speller or a group choice, or aggregate single-trial detections so that a group detects a target more reliably than the best individual.

The gains are real for detection-style tasks where errors are roughly independent across people, so fusion cancels noise; they shrink when users share the same bias or the same stimulus artifact, which correlates their errors. Collaborative BCIs are the read-only, output-sharing cousin of multi-brain interfaces, and are far closer to practical use because they avoid the hard, unsolved write problem entirely.