Effects of Cueing and Knowledge of Results on Workload and Boredom in Sustained Attention

Two accounts of the recently reported high workload associated with vigilance tasks (Warm, Dember, & Hancock, 1996) are the direct-cost and indirect-cost views. The former attributes this effect to the need for continuous observing in discriminating signals from noise; the latter attributes the effect to combating the boredom associated with vigilance tasks. These opposing views were tested by providing monitors with reliable cueing which rendered observing necessary only when low probability critical signals were imminent. On the basis of the direct-cost model, it was anticipated that cueing would lead to low workload but high boredom, since observers would have little to do during most of the vigil; the indirect-cost model would lead to a prediction of both high workload and high boredom. The results clearly supported the direct cost view that the workload of vigilance is task induced. Also as predicted from the direct cost account, cueing led to lower workload than did knowledge of results.