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. Author manuscript; available in PMC: 2014 Jul 1.
Published in final edited form as: AIDS Behav. 2013 Jul;17(6):1915–1925. doi: 10.1007/s10461-013-0475-3

Figure 2.

Figure 2

Figure 2a. Vygotskian model of tool-mediated action

Figure 2b. Engeström’s “Activity System”

Note that the Vygotsky triangle from Figure 2a is the top part of this diagram.

Figure 2c. Stetsenko’s CHAT model of interrelated non-linear, overlapping and often-contradictory processes.