Effects of cueing and knowledge of results on workload and boredom in sustained attention

Two models of recently reported high workload associated with vigilance tas ks are the direct-cost and indirect-cost views. The former attributes high workload to the need for continuous observation in discriminating signals f rom neutral events; the latter attributes it to efforts to combat the bored om associated with monotonous vigilance tasks. These opposing views were te sted by providing observers with reliable cueing, which rendered observatio n necessary only when low-probability critical signals were imminent, or wi th knowledge of results (KR) regarding performance efficiency. On the basis of cue and KR differences in elicited observation activity and motivationa l value, the direct-cost model led to the anticipation that cueing would re sult in a high-boredom, low-workload profile and a greater reduction in wor kload than KR. The indirect-cost model led to the prediction that cueing wo uld result in a high-boredom, high-workload profile and a lesser reduction in workload than KR. The results clearly supported the direct-cost view tha t the workload of vigilance is task-induced. Consequently, efforts to comba t high workload in complex automated systems requiring substantial monitori ng by operators should focus specifically upon task-related determinants.