We describe two experiments that examine 3D pathway displays in a head-up location for aircraft landing and taxi. We address both guidance performance and pilot strategies in dividing, focusing, and allocating attention between flight path information and event monitoring. In Experiment 1 the 3D pathway head-up display (HUD) was compared with a conventional 2D HUD. The former was found to produce better guidance, with few costs to event detection. Some evidence was provided that attentional tunneling of the pathway HUD inhibits the detection of unexpected traffic events. In Experiment 2, the pathway display was compared in a head-up versus a head-down location. Excellent guidance was achieved in both locations. A slight HUD cost for vertical tracking in the air was offset by a HUD benefit for event detection and for lateral tracking during taxi (i.e., on the ground). The results of both experiments are interpreted within the framework of object- and space-based theories of visual attention and point to the conclusion that pathway HUDs combine the independent advantages of pathways and HUDs, particularly during ground operations. Actual or potential applications include understanding the costs and benefits of positioning a 3D pathway display in a head-up location.

Two experiments examined the effects of display location (head-up and head-down), display clutter, and display intensity on pilot performance in a general aviation-cruise flight environment. In Experiment 1, a low-fidelity simulation revealed that the detection of commanded flight changes and flight-path tracking performance was better in the head-down condition as compared to the head-up condition. In contrast, midair traffic detection was superior with the head-up display (HUD), reflecting an attentional trade-off. Experiment 2 used the same paradigm in a high-fidelity visual simulation. Flight performance was equivalent between HUD and head-down locations. Detection of commanded changes and traffic was better in the HUD condition, revealing the HUD benefits of reduced scanning. The presence of clutter inhibited detection of command changes and traffic in both head-up and head-down conditions. Lowlighting the task-irrelevant clutter did not facilitate detection of commanded changes, however, the clutter cost for detecting traffic was diminished if the added information was lowlighted in the head-down location. The data suggested that attention was modulated between tasks (flight control and detection), and between display areas (head-up and head-down).

Costs and benefits associated with head-up display (HUD) use were assessed by analyzing data obtained from studies in the aviation domain. Eighteen studies investigating the use of HUDs, head-down displays, and conformal displays were included in analyses of flight path tracking and event detection performance. HUD and conformality benefits consisted of faster detection responses to changes in symbology and presentation of traffic, as well as increased flight path tracking accuracy. Further investigation into the HUD data revealed a heterogeneous component, suggesting that factors other than display location were contributing to pilot performance. One factor modulating performance was the relative expectancy of the event. HUD use was advantageous if an event in the environment was expected. However, when an event was unexpected, detection was degraded with the presence of HUD instrumentation. This finding reveals a potential cost due to HUD use when confronted with anomalous situations.

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In this article, the authors empirically assess the costs and benefits of designing an adaptive system to follow social conventions regarding the appropriateness of interruptions. Interruption management is one area within the larger topic of automation etiquette. The authors tested these concepts in an outdoor environment using the Communications Scheduler, a wearable adaptive system that classifies users' cognitive state via brain and heart sensors and adapts its interactions. Designed to help dismounted soldiers, it manages communications in much the same way as a good administrative assistant. Depending on a combination of message priority, user workload, and system state, it decides whether to interrupt the user's current tasks. The system supports decision makers in two innovative ways: It reliably measures a mobile user's cognitive workload to adapt its behavior, and it implements rules of etiquette adapted from human-human interactions to improve humancomputer interactions. Results indicate costs and benefits to both interrupting and refraining from interrupting. When users were overloaded, primary task performance was improved by managing interruptions. However, overall situation awareness on secondary tasks suffered. This work empirically quantifies costs and benefits of "appropriate" interruption behaviors, demonstrating the value of designing adaptive agents that follow social conventions for interactions with humans.