Development and validation of a task load index for process control room operators (PCRO-TLX).

ABSTRACT

Process control room operators (PCRO) perform a range of complex cognitive safety-critical tasks. The aim of this exploratory sequential mixed methods study was to develop an occupation specific tool to measure the task load of PCRO using NASA Task Load Index (TLX) methodology. Participants were 30 human factors experts and 146 PCRO at two refinery complexes in Iran. Dimensions were developed via a cognitive task analysis, a research review, and three expert panels. Six dimensions were identified perceptual demand, performance, mental demand, time pressure, effort, and stress. Data from 120 PCRO confirmed that the developed PCRO-TLX has acceptable psychometric properties, and a comparison with the NASA-TLX confirmed that perceptual, not physical, demand was relevant for measuring workload in PCRO. There was a positive convergence of scores of the Subjective Workload Assessment Technique and the PCRO-TLX. This reliable tool (α = 0.83) is recommended for risk assessing the task load of PCRO.Practitioner summary: There are benefits of having a specific tool to measure task load in safety critical roles. Thus, we developed and validated an easy-to-use targeted tool, the PCRO-TLX, for process control room operatives. Timely use and response will assure optimal production alongside health and safety in an organisation.Abbreviations PCRO process control room operator; TLX task load index; PCRO-TLX process control room operator task load index; NASA-TLX National Aeronautics and Space Administration task load index; SWAT subjective workload assessment technique; DALI driving activity load index; SURG-TLX surgery task load index; SIM-TLX virtual reality simulation task load index; VACP visual, auditory, cognitive and psychomotor; CVI content validity index; CVR content validity ratio; RMSEA root mean square of error approximation; GFI goodness of fit index; AGFI adjusted goodness of fit index; CFI comparative fit index; ANOVA analysis of variance; CI confidence interval.