As mentioned before, designers need more formal methods to choose the most appropriate technology for a specific task. Bad decisions at the design stage are often the source of later operational problems that are very hard to fix.

One practical way to examine the viability of technology for future implementation is to consider the interaction features associated with that technology. Another way is to consider the characteristics of the work domain and the context of use. This would include the practical, economic, organisational, operational, regulatory and contextual considerations.

In examining the key entities, principles and relationships between technologies and the contexts where technologies are used, five key dimensions or contexts are identified that could serve as a framework for evaluation and deployment of HSI technologies for new designs. Figure 7.1 identifies these dimensions and specific HSI topics and elements associated with each. The five dimensions or contexts shown (human factors, technology, operations, organisation and regulations) are defined in the following sections.

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efficiency and satisfaction with which specific users can perform specific tasks with specific systems in a given context.

Human performance can be affected positively or negatively by technology and this is determined by a number of factors: the work and environmental context within which a tool is used, the experience and skill with which a person can use the tool, the design of the tool and how usable it is in the given task context. Optimal human performance could therefore be expressed in terms of criteria such as comfort, efficiency, situation awareness, low workload, low error probability and so on. It also means that human performance can often be improved by providing some form of task support to help in reducing operator workload, reducing visual and cognitive complexity of the HSI and making information more accessible.