Perception Over Personality in Lethal Force: Aggression, Impulsivity, and Big Five Traits in Threat Assessments and Behavioral Responses due to Weapon Presence and Posture

The use of lethal force is a combination of threat perception and individual judgment that sometimes warrants a behavioral response. This simplified description implicates perceptual factors and individual differences in lethal force decision making, which ongoing research continues to address. However, personality-based factors have been less explored as to how they might affect either threat perception or behavioral responses in a lethal force decision. The current investigation examined multiple personality traits with the potential to influence lethal force decision making, including aggression, impulsivity, and the Big Five traits. These measures were compared to threat perception and behavioral responses made to a variety of lethal force stimuli broadly categorized as clear threats, ambiguous threats, and clear nonthreats. Samples were recruited from combat-trained infantry, military recruits, and the civilian community to control for prior lethal force training. Although there was a strong omnibus relationship between threat perception and the likelihood of a behavioral response, neither military training nor personality differences had any impact on threat perception or a binary (e.g., shoot/don't-shoot) behavioral response. Therefore, we conclude that perception dominates personality in lethal force decision making when the threat assessment decision is limited to factors such as weapon presence or posture rather than emotion.

The role of inhibitory control in shoot/don't-shoot decisions

Previous work has demonstrated a link between cognitive abilities, specifically inhibitory control and lethal force decision-making performance. However, many previously used approaches to simulating shoot/don't shoot scenarios have lacked ecological validity. There is a need to investigate how inhibitory control impacts shoot/don't decisions using realistic simulations to better translate the findings to military and law enforcement settings. This study used multiple cognitive control tasks incorporating discrete judgements in go/no-go and stop signal tasks as well as subjective judgements in go/no-go tasks with both colour stimuli and emotional faces. These combined tasks provided a comprehensive evaluation of inhibitory control abilities. To ensure ecological validity in shooting performance, existing military training scenarios incorporated realistic weaponry and aiming behaviours across different shoot/don't-shoot simulations. The inhibitory control battery identified five principal components from the various tasks, including: stopping ability, response speed, emotion detection, colour detection, and emotional biases. These principal inhibitory control components were entered into hierarchical linear regressions with the dependent variables of unintended casualties inflicted and lethal rounds fired, respectively. Stopping ability better predicted the likelihood of inflicting an unintended casualty, whereas response speed better predicted the number of lethal rounds fired. These regression models included baseline metrics of marksmanship and shots fired, which supports a role for inhibitory control above and beyond basic shooting abilities or strategy. These collective findings provide mechanistic support for the relationship between inhibitory control and errors in shoot/don't-shoot decision-making while using realistic military training scenarios.

Response Complexity Reduces Errors on a Response Inhibition Task

OBJECTIVE

The purpose of this investigation was to elucidate the role of button-response complexity to targets in a response inhibition task.

BACKGROUND

Response inhibition is the ability to correctly inhibit an overt response to a target. The U.S. military is actively pursuing development of armed, combat robots as a force multiplier, which may present challenges to operators of combat robots in the form of response inhibition errors.

METHOD

A total of 15 participants completed two 51-min versions of a modified sustained attention to response task (SART). Participants were outfitted with an electrocardiogram to index heart-rate variability and completed the NASA-Task Load Index (NASA-TLX) to index workload.

RESULTS

The results demonstrated that the complex SART reduced errors of commission (4%) and slowed response times (874 ms) to correct Go targets relative to the simple SART (14%, 739 ms). The NASA-TLX did not show differences between the modified SARTs; however, heart-rate variability did demonstrate that Soldiers had an increased autonomic stress response to the complex SART.

CONCLUSION

Increasing the behavioral response requirement during a response inhibition task can decrease errors of commission; however, it comes at the cost of slower response times to target stimuli. Heart-rate variability may provide better insight into objective workload relative to subjective measures.

APPLICATION

The use of complex behavioral responses may provide a viable option to reduce potential "friendly fire" or collateral damage by Soldiers remotely engaging a target-rich environment.

The quick and the dead: A paradigm for studying friendly fire

The Sustained Attention to Response Task (SART) is a computer based Go-No-Go response task. Participants respond to frequently occurring neutral stimuli and withhold responses to rare target stimuli. Researchers have suggested the inhibition demands of the SART may mirror those which occur in some firearm accidents. Participants in the present experiment used a simulated nonlethal weapon to subdue threats (images of people holding guns) on large screens. Participants completed a target rich task (high Go low No-Go, like a SART), a target sparse task (low Go/high No-Go), a verbal recall task, and dual versions of the target rich and target sparse tasks with the verbal recall task as the secondary task. Results provided further evidence that some accidental shootings may result from failures of response inhibition and that additional cognitive load is detrimental to overall performance. Future studies should explore the role of response inhibition in realistic firearm scenarios.