Abstract
Purpose :
Defence personnel utilising head-up displays need to attend to a range of sensory inputs and carry out multiple tasks to be successful with missions. These displays are often binocular and subject to optical misalignment that can vary over time. Realigning the displays currently requires a significant period of time with that display being unavailable for operations. This study examined the effect of misalignment on eye movements, autonomic responses and task performance whilst flying simulated missions with a high secondary task load.
Methods :
Six participants (two female, four male) flew a simulated helicopter tail-chase task whilst undertaking secondary cognitive (mental arithmetic), visual (peripheral gauges) and audio (call sign) tasks. Participants had their eye movements measured using Tobii Pro glasses (100Hz) with lenses attached to induce misalignment. All participants regardless of past flying experience were given at least one training session to learn how to fly the simulator and to ensure understanding of the tasks required. Only once participants were comfortable with the flying task were the two conditions of misalignment (30 arc minutes dipvergence and 30 arc minutes divergence) and no misalignment tested, each for an hour. Skin temperature was monitored during the task. Cohen’s d effect sizes were calculated for all variables.
Results :
A reduction in accuracy (d=1.43 audio, d=0.58 arithmetic, d=0.50 tail chase) and an increase in response time (d=0.43 visual, d=0.79 arithmetic) was seen in the misaligned condition. Eye movement data from one participant was excluded due to poor data quality. Eye movement results across five participants show a trend towards an increase in the dwell time to peripheral gauges (d=0.36), as well as an increase in the number (d =0.42) of and duration (d=0.10) of fixations to the peripheral gauges for the misaligned task. Pupil size displayed a decrease for both conditions, larger for the misaligned condition (d=0.43). Skin temperature decreased (av 6.5%) significantly during the misaligned task (p=0.0056).
Conclusions :
Our results show a decrement in performance with misalignment as well as a change in the allocation of cognitive resources away from the primary task.
This abstract was presented at the 2019 ARVO Annual Meeting, held in Vancouver, Canada, April 28 - May 2, 2019.