An examination of the physiological and psychological processes relating to decisions to shoot by police firearms officers

  • Stephen Lewis Brown

Student thesis: Doctoral Thesis


The purpose of this study was to examine how police firearms officers would react when confronted by a sudden stimulus in the form of a highly agitated and aggressive male. This was borne out of a notion that police, in a similar fashion to non-police, would suddenly baulk and struggle to react. This reaction time is critical for survival especially if the assailant is armed with a firearm.

There were three distinct methods used during this research, observation, experimental (four levels: a - d) and questionnaire, with each attracting their own null and alternative hypothesis for testing. Participants (n = 48) wore a heart rate monitor as a proxy for measuring stress and their movements were captured using a high-speed camera. There were a number of key measurements, namely heart rate, reaction and accuracy, analysed using SPSS (24), with key findings evaluated against existing literature.

There were a number of noteworthy findings: All participants followed an action reaction continuum when deciding to shoot or not to shoot. There was a subliminal interval gap (.45 secs) between aiming the weapon and discharging a round. Providing an intelligence briefing to participants resulted in faster (33%) reaction and participants experienced a myriad of perceptual distortions. High stress levels were associated with positive reaction whereas low levels were associated with a negative reaction.

Practical implications
There is a real need to implement realistic and stressful training conditions as a form of inoculation to stress. New tactics of placing a hand on their weapon should be adopted. Decision makers (Investigators and defence teams) must consult an expert with regards to perceptual distortions.

This is the only study to encompass all the relevant actions associated with police use of firearms. This included sensory input, cognition, reaction, shoot or not, perceptual distortions and stress.
Date of AwardSept 2018
Original languageEnglish
Awarding Institution
  • University of Portsmouth
SupervisorAndy Williams (Supervisor) & Claire Rhodes (Supervisor)

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