Justin Brooks

Examining sentiment in team communications can provide information about trust among teammates. Natural language processing (NLP) models provide an efficient means of sentiment analysis. However, military teams and other professional teams use language that differs from what NLP models are trained on, leading to potentially inaccurate sentiment analysis. This study investigates the novel application of two advanced NLP models, DistilBERT and GPT-2, for sentiment analysis of expert military teams conducting AI-supported combat missions in a high fidelity simulation environment. Our fine-tuning process resulted in improved sentiment classification accuracy. The sentiment measures also correlated with measures of team trust and trust in the AI systems, providing valuable insight into the relationship between sentiment and trust in human-AI teaming scenarios. The generalized approach we describe may be useful for adapting sentiment analysis and NLP techniques to military teams, and may help measure trust dynamics and team states in human machine integrated teams.

Dynamic intra-individual variability (IIV) in cardiac vagal control across multiple situations is believed to contribute to adaptive cognition under stress; however, a dearth of research has empirically tested this notion. To this end, we examined 25 U.S. Army Soldiers (all male, Mean Age= 30.73, SD = 7.71) whose high-frequency heart rate variability (HF-HRV) was measured during a resting baseline and during three conditions of a shooting task (training, low stress, high stress). Response inhibition was measured as the correct rejection of friendly targets during the low and high stress conditions. We tested the association between the standard deviation of HF-HRV across all four task conditions (IIV in vagal control) and changes in response inhibition between low and high stress. Greater differences in vagal control between conditions (larger IIV) were associated with higher tonic vagal control during rest, and stronger stress-related decreases in response inhibition. These results suggest that flexibility in vagal control is supported by tonic vagal control, but this flexibility also uniquely relates to adaptive cognition under stress. Findings are consistent with neurobehavioral and dynamical systems theories of vagal function.