Original Manuscript Sleep Deprivation and Racial Bias in the Decision to Shoot: A Diffusion Model Analysis David J. Johnson 1,2 , Michelle E. Stepan 2 , Joseph Cesario 2 , and Kimberly M. Fenn 2 Abstract The current study examines the effect of sleep deprivation and caffeine use on racial bias in the decision to shoot. Participants deprived of sleep for 24 hr (vs. rested participants) made more errors in a shooting task and were more likely to shoot unarmed targets. A diffusion decision model analysis revealed sleep deprivation decreased participants’ ability to extract information from the stimuli, whereas caffeine impacted the threshold separation, reflecting decreased caution. Neither sleep deprivation nor caffeine moderated anti-Black racial bias in shooting decisions or at the process level. We discuss how our results clarify dis- crepancies in past work testing the impact of fatigue on racial bias in shooting decisions. Keywords decision to shoot, racial bias, sleep deprivation, caffeine, diffusion decision model An important question in understanding racial disparities in fatal police shootings concerns the role of sleep deprivation in officers’ decisions. Although it has been hypothesized that sleep deprivation is a cause of both errors in fatal shootings and racial disparity in those shootings (e.g., the shooting of Botham Jean; Shepherd, 2019), direct data on this issue have been equi- vocal. In the current study, we examined whether sleep depri- vation increases errors and racial bias in decisions to shoot and whether caffeine mitigates these effects. Fatigue and Policing Although work hours are federally regulated in many profes- sions, police officers often work long shifts, secondary jobs, and overtime (Vila & Kenney, 2002). Overtime is often not evenly distributed; officers in high-crime areas work on aver- age more than 20 hr overtime per month, with some working up to 70 hr per month (Vila, 1996). In one survey, officers reported working over 60 hr per week, and 70% reported get- ting only 3–6 hr of sleep (Senjo, 2011). Another survey found 29% of officers reported excessive sleepiness (Rajaratnam et al., 2011) and 40% had a sleep disorder. These officers were more likely to fall asleep while driving, have safety violations, or show anger toward suspects (Rajaratnam et al., 2011). Laboratory research on officer fatigue has found similar results. After 5 days of 10 hr shifts, night-shift officers were more likely to deviate from their lanes in a simulated driving task (S. M. James & Vila, 2015). Similarly, L. James et al. (2018) employed a use-of-force simulator, where officers inter- acted with civilians in scenarios that could either escalate or deescalate. Fatigued night-shift officers were more likely to respond in ways that resulted in deadly outcomes compared to fatigued day-shift officers. Fatigue and Shooting Decisions Although the relationship between fatigue and deficits in police performance generally is robust, research on simulated shooting decisions has shown only weak fatigue effects. Stud- ies using an immersive shooting simulator have shown no impact of fatigue (i.e., 5 days of 10-hr shifts) on officer deci- sion accuracy (L. James et al., 2017). Research on shooting decisions with students has also not found a main effect of fatigue on decision making (Ma et al., 2013). A related issue concerns the impact of fatigue on racial bias in shooting deci- sions. Police officers did not show more racial bias in a shoot- ing simulator when fatigued (L. James et al., 2017), whereas fatigued students and police recruits have shown more racial bias in shoot/don’t shoot tasks (Ma et al., 2013). Thus, it 1 Department of Psychology, University of Maryland at College Park, MD, USA 2 Michigan State University, East Lansing, MI, USA Corresponding Author: David J. Johnson, Department of Psychology, University of Maryland at College Park, 4094 Campus Dr., College Park, MD 20742, USA. Email: djjohnson@smcm.edu Social Psychological and Personality Science 1-10 ª The Author(s) 2020 Article reuse guidelines: sagepub.com/journals-permissions DOI: 10.1177/1948550620932723 journals.sagepub.com/home/spp