Extending hierarchical task analysis to identify cognitive demands and information design requirements.

While hierarchical task analysis (HTA) is well established as a general task analysis method, there appears a need to make more explicit both the cognitive elements of a task and design requirements that arise from an analysis. One way of achieving this is to make use of extensions to the standard HTA. The aim of the current study is to evaluate the use of two such extensions--the sub-goal template (SGT) and the skills-rules-knowledge (SRK) framework--to analyse the cognitive activity that takes place during the planning and delivery of anaesthesia. In quantitative terms, the two methods were found to have relatively poor inter-rater reliability; however, qualitative evidence suggests that the two methods were nevertheless of value in generating insights about anaesthetists' information handling and cognitive performance. Implications for the use of an extended HTA to analyse work systems are discussed.