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Optimizing the time and accuracy with which peripheral tasks can be monitored concurrent with a central primary task is of paramount importance for human factors researchers developing human systems. Nonetheless, the design of peripheral task are often evaluated in isolation, and their effectiveness is assumed to generalize to multi-task contexts. Our work acknowledges that peripheral displays may be utilized in a variety of operational contexts. Across four experiments we examine peripheral task detection speeds under several contextual factors related to operator workload and task-set. We use the capacity coefficient from the Systems Factorial Technology framework to quantify the extent that context influences redundant signal enhancements in a peripheral detection task. Across four experiments we manipulated the presence, difficulty and stability of the primary task to simulate different workload contexts.Using a novel time-varying estimate of workload capacity, we show that efficiency in detecting redundant peripheral targets decreases with high primary task demands, contrary to previous findings. Our results also indicated higher capacity in less stable environments but a correspondingly greater workload impairment in these conditions.Implications for system design include consideration of the expected operator workload, as well as attention recruiting strategies to improve peripheral task detection speeds.

The usability of the human-machine interface is dependent on the quality of its design and testing. Defining clear criteria that the interface must meet can assist the implementation and evaluation process. These criteria may be based on performance, the quality of users’ experience, error prevention, or the broad utility of the interface. In this article, we motivate the use for workload capacity as an empirical measure of usability. We first describe generic and specific uses for workload measures in terms of adaptive interfaces. We then carry out a systematic review of how workload capacity has been empirically measured, based on 172 relevant literature sources from psychology, neuroscience, engineering, and computer science. We then analyse and report on how workload capacity and related constructs, such as perceptual load, attention, and working memory have been defined and measured in these sources. We discuss similarities and differences between constructs and identify opportunities for integrating real-time workload capacity measures into dynamic interfaces.

Objective To test the effects of enhanced display information (“symbology”) on cognitive workload in a simulated helicopter environment, using the detection response task (DRT). Background Workload in highly demanding environments can be influenced by the amount of information given to the operator and consequently it is important to limit potential overload. Methods Participants (highly trained military pilots) completed simulated helicopter flights, which varied in visual conditions and the amount of information given. During these flights, participants also completed a DRT as a measure of cognitive workload. Results With more visual information available, pilots’ landing accuracy was improved across environmental conditions. The DRT is sensitive to changes in cognitive workload, with workload differences shown between environmental conditions. Increasing symbology appeared to have a minor effect on workload, with an interaction effect of symbology and environmental condition showing that symbology appeared to moderate workload. Conclusion The DRT is a useful workload measure in simulated helicopter settings. The level of symbology-moderated pilot workload. The increased level of symbology appeared to assist pilots’ flight behavior and landing ability. Results indicate that increased symbology has benefits in more difficult scenarios. Applications The DRT is an easily implemented and effective measure of cognitive workload in a variety of settings. In the current experiment, the DRT captures the increased workload induced by varying the environmental conditions, and provides evidence for the use of increased symbology to assist pilots.

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