Can you teach yourself synaesthesia?

"A form of synaesthesia in which people experience letters or numbers in colour may be trainable. The discovery could shed new light on how such traits develop.

Synaesthesia is thought to have a genetic component, but some people have reported synaesthetic experiences following hypnosis, so Olympia Colizoli at the University of Amsterdam in the Netherlands, and colleagues, wondered if it might also be possible to acquire synaesthesia through training.

To test the idea, they gave seven...