This article is an accurate description of the PPIG work. I attended a couple of PPIG workshops and was active on the ppig mailing list for 16 years (I was booted off for not willing to be politically correct), while working on a book that tried to apply cognitive psychology to language use pdf available here.
“The Psychological Study of Programming” by B. A. Sheil, from 1981, says the same about psychology of programming research in general (cannot find an ungated copy).
The main problem is that few of those involved have ever studied psychology (which has very good experimental practices, at least in cognitive psychology).
The article is nice. The list of 3-sentence summaries of all 530 PsOfPr papers is beyond nice, it is fascinating to read. Many thanks for posting this.