Applied Ergonomics 84 (2020) 103032 Available online 10 January 2020 0003-6870/© 2019 Elsevier Ltd. All rights reserved. The quick and the dead: A paradigm for studying friendly fre Annabelle Munnik, Katharina N€ aswall, Graeme Woodward, William S. Helton * University of Canterbury, Christchurch, New Zealand A R T I C L E INFO Keywords: fratricide Friendly-fre Mindlessness Motor control Response inhibition Sustained attention ABSTRACT 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 frearm accidents. Par- ticipants 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 frearm scenarios. "I remember thinking for just a second or two, but what felt like longer — your perception of time in the midst of a frefght can be distorted — that if he’d fred, and without any other information to indicate a friendly position, that I should also fre" (Neuman, 2014). The above quote was made by Steven Elliot when he was interviewed about the friendly fre incident that resulted in the death of U.S. Army Ranger Pat Tillman in Afghanistan in 2004. As Elliot relays frefghts are confusing, fast—paced scenarios that rule out any long deliberation about the possible outcomes of one’s decisions, including consequences of those decisions. Friendly fre, “the employment of friendly weapons and munitions with the intent to kill the enemy or destroy his equipment or facilities, which results in unforeseen and unintentional death or injury to friendly personnel” (Department of the Army, 1992, p. 3), is an increasing concern for modern militaries. Webb and Hewett (2010), for example, indicate an increase in the percentage of both wounded in action and killed in action resulting from fratricide from WW1 to Operation Desert Storm. Some researchers estimate that friendly fre accounts for between 10% and 24% of all allied-force causalities in modern combat (Gadsden et al., 2008; Schraagen et al., 2010). Similarly collateral damage, the unintentional death or injury of civilians or non-combatants, is an all too frequent occurrence (Crawford, 2015). Concern regarding accidental shootings due to decision errors extends also to law enforcement and civilian hunting. Although some researchers investigating friendly fre and collateral damage focus on the possibility of perceptual failures, confusing the enemy for friendlies or non-combatants, a newer line of research is examining these errors from a response—strategy perspective (Biggs, 2017; Biggs et al., 2015; Head et al., 2017; Helton, 2009; Helton et al., 2011; Helton and Kemp, 2011; Helton and Russell, 2011; Stevenson et al., 2011; Wilson et al., 2015). Noticing structural similarities be- tween the laboratory Sustained Attention to Response Task (SART; Robertson et al., 1997) and what may occur in some shooting scenarios, Helton and colleagues suggested studying friendly fre with tasks anal- ogous to the SART. The SART is a Go-No-Go task requiring participants to respond to frequently occurring neutral stimuli (89% of the time) and withhold responses to rare target stimuli (11% of the time). The SART originally employed number stimuli, 1–9, but other versions of the task have been developed in which non-number stimuli have been utilized (Head and Helton, 2012). A speed–accuracy trade-off (SATO; Dang et al., 2018) is a key feature of the SART, in that participants who respond fast also tend to make more commission errors than those who respond slower. The SART’s motor control and response strategy com- ponents may mirror the underlying processes occurring during some accidents in combat, law enforcement, and civilian hunting (Wilson et al., 2015). In particular, similarities may occur when the environment is target rich or expected to be target rich, or in other settings where the participant would have reason to trade-off decision speed for decision accuracy. The prepotent motor response may develop as participants struggle to fulfl task requirements of responding as fast and as accurately as * Corresponding author. Department of Psychology, George Mason University, 4400 University Drive, 3F5, Fairfax, VA, 22030, United States. E-mail address: whelton@gmu.edu (W.S. Helton). Contents lists available at ScienceDirect Applied Ergonomics journal homepage: http://www.elsevier.com/locate/apergo https://doi.org/10.1016/j.apergo.2019.103032 Received 3 December 2018; Received in revised form 23 November 2019; Accepted 11 December 2019