A dual-task technique for developing mental workload scales was described and evaluated. This technique, the method of double trade-off curves, can be used to equate secondary task performance levels of different tasks. The results from two different mental workload experiments were consistent with the assumptions underlying the technique.

Twelve subjects performed the airplane task, a test of spatial ability, in order to determine whether or not the task is suitable for inclusion in the CTS battery. Subjects performed 12 trials of the task on four consecutive days. Both performance and subjective measures were recorded. Three significantly different loading levels were obtained using the rear, front, and bottom views of the plane. It was concluded that the airplane task appears to be suitable for inclusion in the CTS.

Several tasks in the Criterion Task Set have been modified as a result of validation studies conducted on the original battery. Recent research has established new loading levels for those tasks. In addition to task changes, several modifications have been made in the user interface. Added features include: a 30 second trial option, automatic trial number incrementing, a file naming convention, and a data reduction program.

a b o r a t o r y W r i g h t -P a t t e r s o n A i r Force Base, Ohio 45433 John R . A m e l l Systems Research L a b o r a t o r i e s , I n c . ABSTRACT Background/Ob j e c t i v e