Adaptability of training in simulated process control: knowledge- versus rule-based guidance under task changes and environmental stress.

OBJECTIVE: The study examined the adaptability of different types of process control training across changes in task and environmental stress. BACKGROUND: The literature on training leads us to expect greater flexibility for system-based training, as opposed to procedure-based training. However, the stress literature suggests that knowledge-based strategies (making use of executive control) may be more vulnerable under stress conditions. METHOD: Two groups were given 6 hr of training on the Cabin Air Management System (CAMS), a complex, multilevel, PC-based process control task, emphasizing either system knowledge or use of procedures. They were then required to carry out the task for 3 hr (with noise during the middle 1 hr) across a range of both familiar and unfamiliar fault scenarios. RESULTS: For the primary control task, the system-trained group performed better, especially for less familiar and complex faults. However, for lower priority tasks requiring executive control, procedure-trained operators performed better and were less impaired by noise. CONCLUSION: System training was more effective for managing unexpected task events, whereas procedural training was better under noise. The results are interpreted in terms of the rationale for instructing operators in the range of strategies required for effective process skills in complex work environments. APPLICATION: Training methodologies for safety critical applications should aim to develop skill in the use of both procedural and system knowledge strategies. Operators should be trained in the most effective deployment of these strategies during unfamiliar task events and environmental stress and given stress exposure training.

Cognitive demands of collision avoidance in simulated ship control.

The study examines the cognitive demands of collision avoidance under a range of maritime scenarios. Operators used a PC-based radar simulator to navigate set courses over 100 6-min trials varying in collision threat and traffic density. Corrective maneuvers were made through the application of standard navigation rules and by using two decision aids (target acquisition and test maneuver). Results showed widespread effects of collision threat in terms of decision aid use, subjective workload, and secondary task performance. Most notably, demand increased markedly over the course of emergency trials, in which collision threat resulted from rule violation by target vessels. The findings are discussed in terms of the comparison between predictable demands (requiring standard course changes) and those involving uncertainty about the others' intentions (involving more intensive monitoring and forced delays in corrective action). The study has relevance for the design of collision avoidance systems, specifically for the use of ecological displays.

Performance in a complex multiple-task environment during a laboratory-based simulation of occasional night work.

A study was carried out to examine the impact of occasional night work on simulated process control using a complex task environment. The 21 student participants were tested during 2 6-hr simulated shifts (daytime and night). In addition to the primary system management task, the simulation allowed measurement of fault diagnosis behavior, monitoring and control actions, and two secondary tasks--alarm reaction time and system status checks (prospective memory)--as well as subjective state. Consistent with predictions from compensatory control theory, night work did not impair system performance, although monitoring and control were reduced (supported by subjective reports of increased use of risky "corner-cutting" strategies). Secondary tasks showed an increase in alarm reaction time during night work, but there was no effect on prospective memory and no clear pattern of change in subjective state. Actual or potential applications of this research include the design of complex systems for nighttime operation.

Effects of display design on performance in a simulated ship navigation environment.

Although automation is playing an increasing role on the ship's bridge, empirical research on the effectiveness of alternative bridge designs is limited. In this paper, we describe an experimental study of the benefits of integrated information display, using a computerized simulation of a highly automated ship's bridge. The study compared three types of interface design, which presented radar and electronic chart information to the operator in different ways: (a) integrated display, (b) functionally-separate display, and (c) spatially-separate display. Effects were examined in relation to time on watch and scenario complexity. Following extensive training on the task, 39 participants were tested over a 4-h experimental session, during which they encountered a sequence of collision scenarios of varying complexity. Using a dual-task methodology, a range of measures of primary and secondary task performance were taken, together with assessment of information sampling behaviour and subjective operator state (workload, fatigue, anxiety and situation awareness). The results indicated slight navigational advantages of the integrated display over the two alternative display types, although it also incurred higher levels of operator cost, particularly fatigue. There were no marked effects of time on watch, but more complex scenarios were associated with impaired performance, increased workload and reduced situation awareness. Overall, the findings have suggested some benefits of integrating primary information sources in a ship's bridge environment. The study further confirms the value of experimental simulations as tools for investigating design issues for ship's bridge automation.