I have just read Raymond’s User interface design for interior door locks which reminded me of a curiousity.


Take a look at your telephone’s numeric keypad. The top row of buttons on mine is 1,2,3. Now look at your computer keyboard numeric keypad or a calculator keypad. For mine, the top row is 7,8,9.


A mnemonic to remember a phone number is to visualize the physical path traveled as your finger pushes consecutive digits. It’s inverted when dialing from the keyboard.


Go figure