How many of you can play chords to a song that you've never heard before? What kind of music can you do that with, and what kind of music is difficult? I would offer that someone who can do this well knows theory well, regardless of whether or not he/she knows the names, spellings, and functions of the chords. Is anyone here in that category, of being able to predict chord changes, but not being adept at chord spelling and chord/key relationships? There are a couple of factors at play, of course. For example, some songs have standard 12-bar blues and other types of chord changes. Also, playing through the song once might be dicier at first, but once the progression as cycled through, then you are just repeating what you have just heard. But some songs have non-standard progressions and some people can play them the first time through. I think someone has written a book of common rhythmic patterns for melodies, but is there anything like that for chords? There certainly should be.