First non-invasive human-to-human BBIs

Two 2014 demonstrations established non-invasive human BBIs. Rao, Stocco and colleagues linked a sender's motor-imagery EEG to TMS over a receiver's motor cortex across a campus network, so that imagining a hand movement caused the receiver's hand to press a fire button in a simple game — a single-bit, reflexive command. Grau et al. sent conscious greetings (the words hola and ciao) by encoding letters as binary strings, transmitting each bit by motor imagery, and delivering it to the receiver as a phosphene / no-phosphene event over a transcontinental link.

These are proofs of principle, not communication tools. Throughput is on the order of a bit or two per minute, error rates require slow and redundant signaling, and the message is a code both parties agreed in advance — the sender is not transmitting free thought. Their real contribution was to show that an end-to-end read-transmit-write loop between two human brains can be closed non-invasively.