ABSTRACT
Primary task measures assess the capability of the operator to perform the task or system function of primary or principal interest (e.g. pilot the aircraft, control the system). Speed and accuracy measures are commonly employed, and so are assessments of multiple aspects of operator performance (e.g. ability to maintain proper altitude, speed, and glide slope on final approach in an aircraft). The use of primary task measures is based on the hypothetical workloadperformance relationship noted above. This relationship assumes that as workload increases beyond the information
processing limits of the operator, degradations in primary task performance will result from the inability of the operator to deal with the processing demands of the task or system.
