I once read that colour-blind synaesthetes (or color-blind synesthetes, for you furriners) were able to perceive colours through synaesthesia that they were phy

I once read that colour-blind synaesthetes (or color-blind synesthetes, for you furriners) were able to perceive colours through synaesthesia that they were physiologically incapable of perceiving with their eyes. Thus they abnormally associated concepts with normal colours that were abnormal to them.