Instantaneous Measures of Mental Workload: An Initial Investigation

Abstract

Many researchers have implicitly or explicitly averaged measures of mental workload over a given run or period of time. This process tends to mask specific features (e.g. peaks) of interest in the flow of instantaneous mental workload (IMWL). A study was conducted in which thirty subjects performed computer tasks which quantifiably varied in difficulty during a run. These tasks emphasized perceptual, mediational, psychomotor, and storage and retrieval from short-term memory processes. Data were gathered on the following candidate measures of momentary load: instantaneous primary task performance, instantaneous Michon tapping and time estimation secondary task performance, instantaneous pulse and respiration rates, and two types of online subjective opinion. Data were short-term averaged and used to develop regression models to evaluate the ability of the measures to track IMWL. Primary task performance (response time for functional subtasks) and both forms of online subjective opinion measures showed great promise as measures of IMWL.