We played it when I was in high school, but we called it Egyptian Ratscrew.
(Egyptian Ratscrew, or "ERS" in the company of adults, is a card game that, depending on variant, can include 1-back, 2-back, or 3-back, among other simultaneous pattern recognition tasks. With a nonstandard deck of cards with more features, e.g. Set cards, it would be trivial to adjust it to multi-feature n-back.)
Sorry if replying to an old post is frowned upon but, I have been doing N-Back for a while now and have seen drastic improvements in my learning ability (problem solving?) at school. I'm in my late 30's and was born with learning disabilities (most people are). I know that at least 2 back has helped me.
The reason I'm replying to this post is that I did searches on youtube for Egyptian Ratscrew and the explanations of how to play the game didn't sound or look anything like Dual N Back.
N-Back involves recalling sounds and the position of a visual stimuli. Egyptian Ratscrew does not.
Following up on the 2010 study, Jaeggi and University of Michigan people have run a Single N-back study on 60 or so children.
The abstract is confident and the mainstream coverage unquestioning of the basic claim. But reading it, the data did not seem very solid at all - I will forbear from describing my reservations exactly; I have been accused of being biased against n-backing, however, and I'd appreciate outside opinions, especially from people with expertise in the area.
(Background: Jaeggi 2011 in my DNB FAQ. Don't read it unless you can't render the above requested opinion, since it includes my criticisms.)