Page 84 - JSOM Spring 2026

FIGURE 5 Comparison of marksmanship and cognitive assessment users while transversing a hilly forest with both uphill and
differences between Control and NVG conditions. Results for the six downhill portions during a self-paced 1.1km walk. The dif-
9
targets and two assessments are collapsed across condition separately. fering kinematic findings between studies may be attributed
(A) Shooting Accuracy Scores and (B) Cognitive Assessment Scores
between Control and NVG conditions. Error bars for both graphs to task difficulty. For example, the studies that reported no
represent the standard error of the mean (SEM). significant differences were treadmill-based and lacked the
challenges of operational environments, including dynamic
movements, obstacle avoidance, and decision-making. 18,19 This
suggests that real-world, dynamic movements are impaired by
NVG use compared to daytime conditions, likely due to the
reduced FOV and limited visual cues. 9,18–22 Reduced FOV has
been found to slow walking speed, decrease step length, re-
duce center of pressure stability, and increase sway velocity
during static balance. 20,22 Therefore, the current and previous
studies 9,10,20,22 suggest that over-ground dynamic movement
task biomechanics while wearing NVGs are likely impacted
by reduced FOV, increased graininess, and increased spatial
complexity and disorientation. Therefore, future NVG train-
ing should incorporate high-fidelity dynamic movement tasks
*Indicates significantly lower than Control condition. to prepare warfighters for low-light operations.
FIGURE 6 Comparison of biomechanical differences between
Control and NVG conditions. Results for the six obstacles are Performance Metrics
collapsed across conditions. (A) Toe clearance over obstacle block
measured in centimeters. (B) Toe velocity over block measured in Marksmanship Performance
–1
m⋅ s . (C) Foot angle from horizontal, with negative values denoting NVG use resulted in a 58.2% decline in marksmanship perfor-
increasing dorsiflexion. Error bars for all graphs represent the
standard error of the mean (SEM). mance during dynamic pistol marksmanship tasks (Figure 5).
These results contrasted with those of Weinand and Rommel,
who reported improved marksmanship during a dynamic gun-
fighting course when using NVG (green and white phosphor
color) compared to a traditional light condition in German
Special Operation Forces. The increased marksmanship per-
24
formance observed while using NVGs in Weinand and Rommel
was attributed to infrared targeting lasers, which allowed for
improved target acquisition and were superior to iron sights.
24
As the current study focused on passive aiming and used tradi-
*Indicates significantly different than Control condition. tional sights instead of infrared lasers, we hypothesize that the
reduction in visual acuity and a limited FOV were likely the
Toe Velocity cause for worsening marksmanship performance during NVG
For toe velocity, there was no significant condition × obstacle use in instances when infrared targeting lasers are not feasible.
interaction (F=1.224; P=.295; ηp =.109). There was no main
2
effect for obstacle (F=1.169; P=.305; ηp 0.105); however, As in the current study, marksmanship performance has been
2=
a main effect was found for condition (F=12.954; P=.005; reported to worsen with NVGs, as reflected by increased shot
ηp =0.564) (Figure 6). group size or delayed target detection time during dynamic
2
shooting. 25,26 In the current study, there was no external light
Ankle Dorsiflexion in the room where the study was conducted, resulting in poor
For ankle dorsiflexion, there was no significant condition × visual acuity conditions. The lack of ambient light and the
25
obstacle interaction (F=1.043; P=.331; ηp =0.094). There was reduced FOV are the most likely causes of the reduction in
2
no main effect for obstacle (F=0.909; P=.363; ηp =0.083); marksmanship performance. 25,26 In summary, the use of NVG
2
however, a main effect was found for condition (F=7.281; reduced the wearer’s FOV to 40º and likely impaired visual
P=.022; ηp =0.421) (P≤.05) (Figure 6). acuity, which contributed to the 58.2% decrease in marksman-
2
ship performance.
Discussion
Cognitive Assessment
Biomechanics The cognitive assessment combined visual number card identifi-
NVG use negatively impacted toe velocity (−20.5%), toe clear- cation and basic mathematical skills to assess working memory
ance (+32.2%), and ankle dorsiflexion (+24.0%) compared and sequential processing. There were no detectable differ-
to the control condition (Figure 6). The current literature is ences between the control and NVG conditions in performance
inconsistent regarding the impact of NVG use on biomechan- scores among task 1 (control: 88.0% versus NVG: 89.3%) or
ics. 9,10,18–24 Previous studies reported no kinematic differences task 2 (Control: 89.8% versus NVG: 89.0%). These findings
between the NVG and control conditions during treadmill contrasted with our hypothesis and previous research indicat-
walking for 10 minutes at 4km/h. In contrast, one study re- ing worsening cognitive performance with NVG use. 10,25,26 For
ported a ~23% reduction in movement velocity coupled with example, Alfano and Michel reported a reduced FOV from full
~42% more nonessential movements while using NVG during vision to 9º, which decreased correct spatial recall by 35%.
26
a target search and wayfinding task while another study re- Similarly, Gauthier et al. reported that wearing NVGs led to
10
ported shorter step length in experienced and novice NVG a ~23% increase in time to target while navigating a dynamic
82 | JSOM Volume 26, Edition 1 / Spring 2026