Hierarchical task analysis vs. cognitive work analysis: comparison of theory, methodology and contribution to system design

The cognitive work analysis framework continues to attract increasing attention from the human factors and ergonomics community. Conversely, hierarchical task analysis has been, and remains, the most popular of all human factors and ergonomics methods. This article compares the two approaches in terms of their theoretical underpinning, methodological approach and potential contributions to system design and evaluation. To do this, recent analyses, involving both approaches, of a military rotary wing mission planning software tool are compared and contrasted in terms of their methodological procedure and analysis outputs. The findings indicate that, despite the very different theoretical and methodological nature of the two approaches, and also the entirely different analyses derived, the two methods provide highly complementary outputs. In conclusion, it is argued that there is benefit in applying both approaches to inform the design and/or evaluation of the same product or system.