Conformal Symbology, Attention Shifts, and the Head-Up Display

Abstract

Thirty-two pilots flew instrument approaches in a high-fidelity simulator. Location of flight symbology was manipulated head-up vs. headdown while controlling for optical distance and symbology format. Pilots were assigned to one of two symbology sets, conformal and nonconformal. Each pilot flew half of the trials with the symbology presented in a head-up location and half with the symbology located headdown. Airspeed tracking for both groups was displayed with non-conformal digital symbology. An unexpected far domain event was presented on one trial per pilot. The results revealed that, for flight path control, there was generally a cost associated with headdown location. The magnitude of this cost was larger for conformal than for non-conformal symbology. Head-up presentation resulted in faster transition from instrument to visual flight reference, but poorer airspeed tracking and slower response to the far domain unexpected event and greater error tracking digital airspeed. The results are interpreted with the theoretical framework of object-based and space-based theories of visual attention, and the tradeoffs between clutter of overlapping imagery and information access cost.

Current and future helmet-mounted displays for piloted systems

“…It is bisected with a solid line meant to represent the horizon. The "objectness" of this particular symbology format is thought to enable more effective perception of the visual information presented, 22 and indeed, at least two studies have confirmed its effectiveness in increasing attitude maintenance performance. 21,23 Cylinder.…”

“…Foyle, McCann, and Shelden 30 argued that displaying conformal symbology on a HUD is particularly attractive for taxiing and other surface operations, and showed that it may alleviate the "attentional-tunneling" problem found with non-conformal HUD symbology. 22 Again, the unique features of HMDs also make them an attractive alternative platform for the display of scene-linked symbology. Some research supports this contention.…”

Cognitive Issues Related to Advanced Cockpit Displays: Supporting the Transition between Internal and External Guidance

“…Researchers have identified a potentially dangerous consequence of using HUDs known as attentional tunneling, or attending to the information presented on the HUD at the expense of the view outside the cockpit window (e.g., Foyle et al, 1995;Wickens andLong, 1994 and1995;Hooey, et al, 2001). This problem can be alleviated by replacing superimposed symbology (in which the symbols are mostly presented at a fixed, specific location on the HUD screen) with scene-linked, conformal symbology (in which the symbols are virtually placed in the outside scene and appear to be part of the environment).…”

U.S. Army weapon systems human-computer interface style guide. Version 2

“…The design goal to reduce soldier scanning can be neutralized or defeated by too much clutter fiom nonconformal symbology. (Wickens and Long 1994) …”