Cognitive load and the role of cue utilisation during sustained attention tasks

One of the key roles of system controllers in high risk environments, such as rail control, power control, and driving, is to recognise, anticipate and respond to changes in the system state. This requires that operators sustain a visual search to monitor and control their operating systems, often for extended periods. However, attentional resource theory posits that sustaining attention over extended periods results in the consumption of cognitive resources, thereby reducing the residual resources available to manage changes in the system state. The utilisation of cues is a cognitive strategy that operators engage to reduce the rate at which cognitive resources are consumed. The aim of this thesis was to examine whether differences in cue utilisation are associated with differences in the rate at which cognitive resources are consumed across a range of operational settings, under a range of operational conditions, and using operators of varying levels of operator experience. Studies 1 and 2 w ere conducted to establish whether a general capacity for cue utilisation predicts differences in the consumption of cognitive resources during sustained attention tasks. The results of Study 1 indicated that participants with higher cue utilisation recorded smaller increases in mean response latency during a novel 30 - minute rail control simulation, compared to participants with lower cue utilisation . Study 2 replicated and extended these results using a 45 - minute rail control simulation, demonstrating greater decreases in fixation rates, smaller changes in cerebral oxygenation in the prefrontal cortex, and smaller increases in mean response latency for participants with higher cue utilisation, compared to participants with lower cue utilisation. These results are consistent with the proposition that cue utilisation is associated with the allocation of fewer cognitive resources to sustained attention task. Study 3 was designed to validate a newly adapted sustained visual search task for process control environments. The results revealed changes in response latency throughout the sustained visual search task that were positively associated with changes in response latency 12 during a 30 - minute low signal probability rail control task, a 45 - minute low signal probability rail control task, and a 45 - minute high signal probability rail control task. The findings suggest that the sustained visual search task is a valid alternative to a longer - duration process control task for experimental studies. Study 4 was intended to examine whether experienced operators' cue utilisation differentiates performance during domain - relevant sustained attention tasks. In two experiments, power distribution operators with higher cue utilisation demonstrated shorter mean response latencies during a power control sustained visual search task, compared to operators with lower cue utilisation . These results support the view that experienced operators with higher cue utilisation adopt strategies during operational tasks that reduce the demands on cognitive load. Study 5 was designed to establish whether differences in cognitive load based o n cue utilisation are also evident in more dynamic operational environments. Using motor vehicle driving as a context, drivers' consumption of cognitive resources were examined during a 20 - minute , simulated driving task. Qualified drivers with higher cue utilisation demonstrated smaller mean visual saccade amplitudes, smaller mean fixation dispersions, smaller increases in cerebral oxygenation and recorded fewer missed traffic signals during the simulated driving task, com pared to participants with lower cue utilisation . These results are consistent with the broader proposition that experienced operators adopt more efficient search patterns, and consume fewer cognitive resources, during dynamic operational task. Extending these findings, Study 6 assessed physiological measures of cognitive resource consumption during periods of power distribution operators' regular workdays. Across two testing sessions, and controlling for subjective measures of workload, higher cue utilisation was associated with smaller increases in cerebral oxygenation in the prefrontal cortex, which is indicative of lower cognitive load. These results indicate that experience operators with higher cue utilisation are consuming fewer cognitive resources during typical operational tasks, compared to operators with lower cue utilisation. The outcomes from this programme of research provide a number of theoretical contributions that advance an understanding of the relationship between cue utilisation and sustained attention. These contributions include support for the proposition that cue utilisation is associated with the consumption of fewer cognitive resources during sustained attention tasks, the identification of search pattern efficiency as a potential mediator for the relationship between cue utilisation and cognitive load, and evidence to support the resource depletion theory of the vigilance decrement. These findings have applied implications for the selection, management, and training of operators in high risk environments.