Effect of Combat Vehicle Operation on Cognitive Workload and Performance

Abstract

Multifaceted stress factors related to infantry combat vehicle (ICV) operation may be considered as major a source of cognitive workload, which may significantly impact the performance of infantry soldiers. The available literature on the effect of ICV’s operational environment on soldier’s cognitive workload is scanty or mostly unreported. The present study was designed to observe the effect of ICV operation on the i) cognitive workload ii) cognitive performance and iii) to study the association between cognitive workload and performance. Thirty soldiers [mean(SD)age: 31.86(2.9) years, weight: 74.40(7.7) kg, and height: 171.33(3.42) cm] volunteered for this study. Their heart rate (HR), heart rate variability (HRV) and respiratory frequency (RF) were recorded at three time points 00th-05th, 25th-30th and 55th-60th minute during the ICV operation. ‘A’ letter cancellation task (ALCT) was conducted to assess cognitive performance, before and after ICV operation. The internal temperature and relative humidity (RH) of ICV were assessed at same three time-points. Repeated measure ANOVA and Wilcoxon signed ranks test were conducted to observe significant changes in HR, HRV, RF, and cognitive performance. Association between HRV and ALCT was assessed using Pearson’s bivariate correlation. Changes were considered significant when p-value was ≤ 0.05. Significant increase in the HR and RF were observed along with significant decrease in both time and frequency domain of HRV after ICV operation. Similarly, ALCT showed a significant increase in the total and net score, and an increased error score in post-ICV operation. A strong positive correlation was observed between the ICV operation run-trial time and the increasing compartmental temperature (r=0.99) and RH (r=0.89). HRV components showed a negative correlation with ALCT measures. One hour of ICV operation resulted in increased cognitive workload and a significant decrease in the cognitive task performance. Internal temperature and RH of ICV are potential physical stress factors affecting the soldier’s workload and performance.