Cultural-historical activity theory was initiated by Lev Vygotsky (1978) in the 1920s and early 1930s. It was further developed by Vygotsky’s colleague and disciple Alexei Leont’ev (1978, 1981). In my reading, activity theory has evolved through three generations of research (Engeström, 1996).

• The first generation, centered around Vygotsky, created the idea of mediation (…) Vygotsky’s idea of cultural mediation of actions is commonly expressed as the triad of subject, object, and mediating artifact (…) Objects became cultural entities and the object-orientedness of action became the key to understanding human psyche (…) The limitation of the first generation was that the unit of analysis remained individually focused.
• The second generation, centered around Leont’ev (…) Leont’ev explicated the crucial difference between an individual action and a collective activity (…) object-oriented actions are always, explicitly or implicitly, characterized by ambiguity, surprise, interpretation, sense-making, and potential for change. The concept of activity took the paradigm a huge step forward in that it turned the focus on complex interrelations between the individual subject and his or her community.
• The third generation of activity theory needs to develop conceptual tools to understand dialogue, multiple perspectives, and networks of interacting activity systems (…) Wertsch (1991) introduced Bakhtin’s (1981) ideas on dialogicality as a way to expand the Vygotskian framework. Ritva Engeström (1995) went a step further by pulling together Bakhtin’s ideas and Leont’ev’s concept of activity, and others have developed notions of activity networks, discussed Latour’s actor-network theory, and elaborated the concept of boundary crossing within activity theory.

In its current shape, activity theory may be summarized with the help of five principles:

• a collective, artifact-mediated and object-oriented activity system, seen in its network relations to other activity systems, is taken as the prime unit of analysis
• the multi-voicedness of activity systems
• historicity as activity systems take shape and get transformed over lengthy periods of time
• central role of contradictions as sources of change and development
• possibility of expansive transformations in activity systems

Expansion is a form of learning that transcends linear and socio-spatial dimensions of individual and short-lived actions (…) learning is understood in the broader and temporally much longer perspective of a third dimension, that is, the dimension of the development of the activity (…) Expansion is the result of a transition process from actions currently performed by individuals to a new collective activity (…) A transition from action to activity is considered expansive when it involves the objective transformation of the actions themselves and when subjects become aware of the contradictions in their current activity in the perspective of a new form of activity.

References

Cambridge University Press. Learning and Expanding with Activity Theory. Edited by Annalisa Sannino, Harry Daniels and Kris D. Gutierrez Frontmatter, 978-0-521-76075-1.

Yrjö Engeström. Expansive learning: Toward an activity-theoretical reconceptualization.

Image available here (Engeström, Y. (2001). Expansive learning at work: Toward an activity theoretical reconceptualization. Journal of education and work, 14(1), 133–156. Taylor & Francis)