Bill D., that's interesting - I knew what synesthesia was, but never connected it with that childhood experience. As described, it differs from my experience in that I 'saw' coloured forms, not just colours, and the effect faded away by the time I was six or seven. I remember missing it. There are a lot of changes in the brain (or at least in behaviours) around age six: as childcare workers, we were taught that many odd behaviours might resolve around that age, and for the most part that proved true, whether for social or neurological reasons.