Affordances in activity theory and cognitive systems engineering

For the last decade, the Gibsonian concept of affordances has attracted much attention within Human-Machine Interaction (HMI) and related research communities. The application of Gibson's ideas in HMI has lead to the notion of direct manipulation of interface objects. Previously, the focus has been on design for low level interaction modalities.

To incorporate the concept of affordances in the design of human computer interaction it is necessary to systematically unravel affordances that support human action possibilities. Furthermore, it is a necessity that Gibson's theory of affordances is supplemented by careful analyses of other human modalities and activities than visual perception.

Within HMI two well established perspectives on HMI, Activity Theory (AT) and Cognitive Systems Engineering (CSE), have discussed such analyses and design of action possibilities focusing on providing computer support for work situations. Within these perspectives, the primary unit of analysis in HMI is human work activity and the socio-cultural context in which this activity is carried out.

Thus, they emphasise the actors' purposeful activity as the most important design rationale. According to previous views in HMI, notably those that have been put forward by Norman and Gaver, affordances are in the foreground, whereas the system or work area is in the background. AT and CSE share the view that the actors' perception of foreground and background shifts dynamically according to the actors' situational context in purposeful activity.

AT and CSE follow the original notion by Gibson on the actor's dynamic shifting between foreground and background of the environment. Furthermore, their work- and actor-centred approach to analysis and design of information systems opens up to an extension of Gibson's original ideas to cover deeper semantic and pragmatic aspects of the ecology of work, as compared with the previous applications of Gibson's theory in HMI.