Investigating the TACOM measure as a general tool for quantifying the complexity of procedure guided tasks

• TACOM scores seemed to be correlated with difficulty rankings and empirical HEPs.
• Two sets of task performance times are gathered from different task environments.
• Task performance times are compared with the associated TACOM scores.
• TACOM measure seems to be applied in common to different task environments.

According to operation experience, it is evident that the role of human operators is critical for securing the safety of complex socio-technical systems. For this reason, various kinds of HRA (Human Reliability Analysis) techniques have been used for several decades in order to systematically manage the likelihood of human error. One of the prerequisites to accomplish this goal is the provision of sufficient data that are helpful for HRA practitioners. In this regard, Podofillini, Park, and Dang (2013) investigated the feasibility of the TACOM (Task Complexity) measure as a tool to represent the effect of a task complexity on the performance of human operators in an objective manner. As a result, it was observed that TACOM scores systematically explain the variation of difficulty rankings and the likelihood of human error being empirically measured. Accordingly, it is possible to expect that the TACOM measure can support HRA practitioners because they can estimate the relative difficulties (or the likelihoods of human error) among tasks based on the associated TACOM scores to some extent. In order to confirm this expectation, however, it is indispensable to ensure the generality of the TACOM measure. From this necessity, task performance time data obtained from different task environments are compared. Consequently, it is believed that the TACOM measure can be regarded as a general tool for representing the complexity of procedure guided tasks because human operators who are faced with similar TACOM scores showed comparable task performance times even under different task environments.