n particular, we note how recent extensions to Activity Theory have addressed theoretical shortcomings similar to our five challenges and suggest directions for bridging the gap between everyday practice and systems support

These extensions increase the complexity of the Activity Theory model but also help to explain tensions present in real-world systems such as when one agent plays different roles in two systems that have divergent goals. Furthermore, this approach provides Activity Theory with a similar degree of agility in representing complex, distributed cognition as competing theoretical approaches, such as Distributed Cognition (Hutchins, 1995).

mporal features. We have then to consider how organizational participants are affected by situations containing temporal features, but also how these actors shape, by their behavior and beliefs, local context according to their needs.

While Activity Theory provides a useful lens for understanding users’ work practices and a language for communicating models of users’ behavior, there are some aspects of work practice that have been shown to be critical for knowledge work but are not captured in the Activity Theory framework. For example, knowledge workers have been shown to rely on the organization of information used in ongoing activities to accomplish their work, particularly when the value or role of that information has not yet been fully determined (Kidd, 1994; Malone, 1983; Mynatt, 1999). Activity Theory alludes to the fact that tools reflect the history of their use, but does not place a strong emphasis on this critical component of knowledge work.

s a means for coordinating action among groups of users (e.g., Bardram, 2005, this volume)

The hierarchical structure of the Boer et al. adaptation of the Activity Theory model can help to reconcile the differences in granularity and the difficulties of supporting collaboration identified in our work; future activity-centered user interfaces might take advantage of the zoomable user interface paradigm or feature control over the level of detail (LOD) represented in the interface to more accurately reflect the depth at which a given user conceptualizes their own tasks or the tasks of their colleagues.

Activity Theory casts a wide but well-defined net around the multifaceted nature of activity, suggesting that the user’s colleagues and the object of the activity are of the utmost importance, but that the tools, social rules, and roles of collaborators within the community must also be reflected back to the user as critical components of that activity. The idea that components of activity reflect their history of use through time suggest several ways for activity-centered systems to support a dynamic working landscape; for example, they might capture past activities in an archive for quick—and potentially automated—reference during related tasks in the future, and that the tools used in previous and ongoing activities (e.g., documents and information resources) both be available at all times and tagged with meta-information about how they have been used in the past

Engeström (1987) provides a classic visualization summarizing the structure of an activity (figure 3). This model is based around three mutual relationships: that between the actor (subject) and the community (other actors involved), that between subject and the object (in the sense of objective) of the activity, and that between the object and the community. These mutual relationships are mediated by the other components of activity.

Activity Theory is described both as a guiding framework for analyzing observations of work practice and a language for communicating those findings within the community of practitioners (Halverson, 2001).

Nardi (1996) argues that one of the inherent strengths of Activity Theory is in its ability to capture the idea of context in user models for HCI, a notion that is gaining momentum particularly with respect to the ubiquitous computing paradigm and as its own design movement, so-called activity-centered design (Gay & Hembrooke, 2003). The world that Gay and Hembrooke envision relies upon design that is not user-centered (which is currently the dominant view in the HCI community) but activity-centered, since Activity Theory provides the right “orientation” for future classes of interactions mediated by ubiquitous computing devices.

Besides the fact that an activity is situated in a network of influencing activity systems, it is also situated in time....In order to understand the activity system under investigation, one therefore has to reveal its temporal interconnectedness....Rather than analyzing an activity system as a static picture of reality, the developments and tensions within the activity system need to be

However, Gay and Hembrooke point out a weakness in the original formulation of Activity Theory: “The model of activity theory...has traditionally been understood as a synchronic, point-in-time depiction of an activity. It does not depict the transformational and developmental processes that provide the focus of much recent activity theory research” (Gay & Hembrooke, 2003).

In their well-known “activity checklist,” Kaptelinin, Nardi, and Macaulay (1999) identified five basic principles of Activity Theory: 1.Hierarchical structure of activity In Activity Theory, the unit of analysis is an activity which is directed at an objectthat motivates the activity. Activities are composed of conscious, goal-directed actions; different actions may be taken to complete any given goal. Actions are implemented through automatic operations, which do not have goals of their own. This hierarchical structure is dynamic and can change throughout the life of an activity. 2.Object-orientedness Activity Theory holds that humans exist in an broadly-defined objective reality, that is, the things around us have properties that are objective both to the natural sciences and society and culture. 3.Internalization/externalization Activity Theory considers both internal and external actions and holds that the two are tightly interrelated. Internalization is the process of transforming an external process into an internal one for the purposes of planning or simulating an action without affecting the world. Externalization transforms internal actions into external ones and is often used to resolve failures of internal actions and to coordinate actions among independent agents. 4.Mediation A central tenet of Activity Theory is that activity is mediated by tools, and that these tools are created and transformed over the course of the activity so that the culture and history of the activity becomes embedded in the tools. Vygotsky’s definition of tool is very broad; one of the tools he was most interested in was language. 5.Development Activity Theory relies upon development as one of its primary research methodologies; that is, “experiments” often include consist of a subject’s participation in an activity and observation of developmental changes in the subject over the course of the activity. Ethnographic methods that identify the cultural and historical roots of activity are also frequently used.

Activity Theory places a strong focus on the mediating role of tools and social practices in the service of accomplishing goals

The acceptance of doing something different has to do with the understanding of a former experience in which there were subjects that were discussed.

the elements—tools and community—seemed to mediate stu-dents’ active participation and motivation in the process of achieving their (subject) learning objectives (object). Tool mediation, which is a key principle of Activity Theory, highlights that human activity is mediated by various tools