I should have posted these a while ago...
Alan Blackwell works on the cognitive
dimensions framework as part of his larger research program on the psychology of programming
and has many useful links to papers etc on his page.
Thomas Green originally
developed the framework and has been the inspiration for a lot of the recent work
on the psychology of programming.
Lastly, I've already mentioned this in a previous posting, but the Psychology
of Programming Interest Group meets once a year to present and discuss some of
the latest research in this field.