Many studies and many areas in HCI and CSCW emphasise the rich ecological setting of human–computer interaction: situated action, distributed cognition, activity theory, ethnomethodological studies. Often those who espouse rich understanding of interaction contrast it with more formal models and reject these as inappropriate for capturing the complexity of human experience and activity.

In the biological disciplines, an appreciation of the complexity of ecological interactions was also a long time coming. However, those studying the biosphere or environmental management do not stop at saying that it is complex, but seek to analyse and model these interactions in order to predict the effects of interventions and manage threatened ecosystems. Similarly, in formal areas of human–computer interaction we need to accept the limitations of our formalisms, but also extend them to incorporate the richer interactions with the work or home environment.

In this context I will discuss a variety of issues that can inform or form part of our formal models:

• the socio-organisational Church–Turing hypothesis – that organisations perform information processing and thus share features with cognitive and electronic computation;
• triggers – understanding why things happen when they happen,
• artefacts – that embody information not just in what they are, but also where they are and how they are disposed in the workplace,
• information – how people use sources to drive and inform their actions
• incidental interaction – systems that respond because people have acted for some other purpose

These can be seen as part of a broader theoretical perspective of embodied computation – that real computation happens in the physical world and that the physical and human world is full of computation.

By having a rich and, where appropriate, formalised understanding of the ecology of human–human and human–computer interaction, we are better placed to ensure that our interventions in the workplace do not lead to ecological catastrophes in the organisation.

keywords: ecology of interaction, formal methods in human-computer interaction, task analysis, task models, artefacts, socio-organisational Church–Turing hypothesis, incidental interaction, triggers