It was Mike who coined the acronym some three years ago, in the midst
of a discussion on whether it is (a) legitimate (b) prudent or
(c) desirable to knit together the strands of the Vygotskian heritage
that center on the cultural/linguistic "mediational means" with the
psychological orthodoxy of the late Soviet period (1960 to 1985 circa),
i.e. with "the" Activity Theory of Alexei Nikolaievitch Leont'ev,
complete with "levels" and phylogenetic, historical, and ontogenetic
speculations and theories coming from this school.
So, "CHAT" in a way forced those lines together: The culture-historical
period of Vygotsky (with the talk about primitive peoples, and
pre-scientific everyday thinking muddles) with the research influenced
by the AT school (with many, many interesting variants in Russia, Estonia,
Hungary, Czekoslovakia, the Germanies, Scandinavia, etc.).
In Vol 1 No. 4 of MCA you will find an article by Jim Wertsch where he
declares "Sociocultural Studies" as an independent stream away from
the idea that cultural differences can be coupled to "differences in
evolutionary status" (p 203), rejecting part of Vygotsky's heritage.
At that time I did not quite understand the motives behind this move,
and discussion via xfamily proved to be very meager. Still, I would
bet that Jim wouldn't use the CHAT label for his work. Also Yrjo
Engestrom was quite reluctant to use it, as far as I can remember.
Maybe enough time has gone down the tunnel now ?
Doubting: Arne.