From Kathryn Bell, London, UK
Your article about synaesthesia didn’t really get into everyday uses for it. I have one: all those PINs and passwords we are expected to remember without writing them down. I write the names of the colours associated with the letters and numbers. It works perfectly for me and is a code that would be hard to break. Also missing from the article are other printed or written marks like brackets and punctuation marks. These are all colourless to me, but perhaps not to everyone. By the way, A is definitely not red and K is dark navy blue, nobody’s favourite (10 June, p 40).
