  Virtual and mixed reality (VR, MR) technologies offer a powerful solution for
on-the-ground flight training curricula. While these technologies offer safer
and cheaper instructional programs, it is still unclear how they impact
neuronal brain dynamics. Indeed, MR simulations engage students in a strange
mix of incongruous visual, somatosensory and vestibular sensory input.
Characterizing brain dynamics during MR simulation is important for
understanding cognitive processes during virtual flight training. To this end,
we studies the delays introduced in the neuronal stream from the retina to the
visual cortex when presented with visual stimuli using a Varjo-XR3 headset. We
recorded cortical visual evoked potentials (VEPs) from 6 subjects under two
conditions. First, we recorded normal VEPs triggered by short flashes. Second,
we recorded VEPs triggered by an internal image of the flashes produced by the
Varjo-XR3 headset. All subjects had used the headset before and were familiar
with immersive experiences. Our results show mixed-reality stimulation imposes
a small, but consistent, 4 [ms] processing delay in the N2-VEP component during
MR stimulation as compared to direct stimulation. Also we found that VEP
amplitudes during MR stimulation were also decreased. These results suggest
that visual cognition during mixed-reality training is delayed, not only by the
unavoidalbe hardware/software processing delays of the headset and the attached
computer, but also by an extra biological delay induced by the headset's
limited visual display in terms of the image intensity and contrast. As flight
training is a demanding task, this study measures visual signal latency to
better understand how MR affects the sensation of immersion.
