STRUCTURAL EQUATION MODELS OF SUBJECTIVE MENTAL WORKLOAD: TASK AND INCUMBENT FACTORS (LISREL, APPLIED STATISTICS, HUMAN FACTORS, AIRCRAFT MAINTENANCE, COVARIANCE STRUCTURES)

Based on an extensive literature review, twenty-two variables including both task and incumbent characteristics were ordered in a theoretical causal hierarchy for subjective mental workload estimates. Data were collected from two samples of aircraft maintenance personnel to enable the exploration of several latent and observed variable structural equation models that were consistent with this hierarchy.;LISREL VI was used to estimate the parameters of these models and test their goodness of fit. An observed variable model was chosen as best fitting and its stability was assessed through simultaneously estimating its parameters from two samples of data. Eighty-six percent of the model's parameters were able to be constrained to be equal for the two samples.;The strengths and weaknesses of this model and the techniques used to develop it are discussed with particular emphasis given to the problems of multicollinearity, the assessment of goodness of fit and the heuristic value of developing such models.;One of the most interesting results of the study was that individual difference variables were found to consistently influence mental workload estimates. The general trend of their influence was such that higher ability people tended to rate given tasks as more demanding of mental workload than lower ability people.