Wadler's Blog

You might also want to check out ICPC: International Conference on Program Comprehension. A lot of their research is on usability of programming languages. They did eye tracking studies on UML to determine what are the fixation points in UML (turns out that the ends of arcs are very important yet too small). Other researchers evaluated the readability of underscores versus camelCase with and without training. Some people evaluated if sonification used for the blind is useful for sighted.
 

Thanks. Here is a link to the ICPC home page.
 

The ICPC proceeding links go to a page with a "please wait" widget that waits forever.
 

ICPC is a nice event, and the UML paper was indeed a really interesting read, but the underscores versus camelCase one ... gosh WTF!? the evaluation consists how fast you can click moving clouds on a computer screen, totally out of the context of source code and its special character soup. Epic fail.