Brooke Schaab U.S. Coast Guard Research and Development Center
The influence of varying levels of workload on performance has been a prevalent topic in human factors and information processing research. The seminal law of Yerkes-Dodson proposed that both high and low levels of perceived stress degrade performance, with optimal performance occurring at some intermediate level. The findings reported in this study were obtained when a task was counterbalanced between increasing and decreasing levels of workload experienced during a simulated air traffic control task. It was found that performance differed depending upon whether participants experienced increasing or decreasing levels of workload.
Ninety-six undergraduates simulated radar "spotters" in a surveillance aircraft. Their task was to monitor a computer display and identify aircraft in the area as a "friend" or an "enemy." A representation of the task is presented in
Increases in workload were produced through the addition of the number of planes that required monitoring (within subjects). Information load was manipulated by increasing the number of criteria used for identifying the aircraft as "friend" or "enemy" (between subjects).
Significant order-by-number of planes-by-half interactions were found for the number of planes acquired (F(3,240)=92.31,p<.01); the number of planes acquired and identified correctly (F(3,240)=64.48, p<.01); and reaction time (F(3,240)= 93.03,p<.01). Overall, performance improved when the number of planes displayed increased in ascending order (4, 8, 12, then 16 planes displayed), with more planes acquired with each increase, more identified correctly, a larger percent correct of those acquired, and a decrease in reaction time. Performance showed a similar pattern in the first and second half, although overall