MODELING DECISION PROCESSES IN THE USE OF LETHAL FORCE: THE ROLE OF RACIAL BIAS IN JUDGING FACES By Jenna Anne Harder A DISSERTATION Submitted to Michigan State University in partial fulfillment of the requirements for the degree of Psychology – Doctor of Philosophy 2020 ABSTRACT MODELING DECISION PROCESSES IN THE USE OF LETHAL FORCE: THE ROLE OF RACIAL BIAS IN JUDGING FACES By Jenna Anne Harder To empirically address the question of whether and why police officers are more likely to shoot Black than White suspects, psychologists have developed the First-Person Shooting Task (FPST): a laboratory task in which participants must make shooting decisions based on rapid assessments of whether a Black or White target is holding a gun versus a harmless object. Typically, studies employing the FPST have found that participants’ errors and reaction times show a bias toward shooting Black targets over White targets. Evidence for the mechanisms behind this bias is mixed, but several studies point to stereotypic associations between the category “Black” and some indication of threat (e.g. weapon possession). Collectively, this past work is suggestive that racial bias on the FPST is influenced by racial bias in threat perception. I investigated this hypothesis across three studies. Participants rated Black and White faces with regard to how “threatening” the faces appeared, then completed the FPST 3-15 days later. Behavioral and process-level (Drift Diffusion Model) methods were used to determine whether racial bias in a participant’s threat ratings explained racial bias in the FPST. Across two stimulus sets, results indicated that although participants displayed process-level racial bias, this was not explained by biased threat perceptions. I consider implications such as the possibility that biased shooting decisions are produced by information-processing mechanisms rather than affective mechanisms. This dissertation is dedicated to Clementine. In all these years, you have never spoken an unsupportive word to me. Thank you for believing in my dreams. iii ACKNOWLEDGEMENTS I am grateful to the Social and Personality Psychology faculty at Michigan State for their support and guidance during my time here. Their influence has valuably improved my abilities to evaluate and produce psychological science. In particular, I would like to thank my committee— Joe Cesario, Debby Kashy, Rich Lucas, and Erik Altmann—for their advice on this work; my dissertation is much stronger because of their contributions. Joe, my advisor, deserves particular recognition for mentoring me throughout graduate school; I am fortunate to have had his influence on the way I think about theory and research design. I’d also particularly like to thank Debby for patiently helping me with countless complicated questions about multilevel modeling over the years. Her instruction and advice have made me a much better statistician. Many thanks as well to David Johnson for his key advice on the diffusion model analyses in this work. The data for this research were collected by a small army of undergraduates, and I thank Meghan Abrom, David Auer, Kelsey Bees, Erin Brooks, Katie Edwards, Kate Frieden, Joe Healy, Erin Kurth, NaVia Miller, Samuel Motzny, Lauren Scott, and Muhammad Shaharuddin for their time and dedication. This dissertation would not have been possible without them. Finally, I’m grateful for all the people who have been sources of support and encouragement during my graduate career. Thank you to my parents, Tim and Julie Harder, my brothers, Jim and Mark Harder, and a host of others including (but not limited to): Katie Leahy, Jeewon Oh, Victor Nahuel Felix de Souza Keller, Rosaura Dominguez, Patricia Maina, Mithila Vidyanath, Kiana Gonzalez, Lindsay Weiss, Clementine Theodosia Weiss, and Nathan Wood. Their support has helped me find the energy and confidence to meet the daily challenges of graduate school throughout the last five years. iv TABLE OF CONTENTS LIST OF TABLES ........................................................................................................................ vii LIST OF FIGURES ....................................................................................................................... ix INTRODUCTION ...........................................................................................................................1 Threat Perception .........................................................................................................................3 Ingroup/Outgroup Categorization and Ingroup Favoritism..........................................................4 Ingroup/Outgroup Bias and Race .................................................................................................5 Analysis of Shooter Data ..............................................................................................................9 The Present Research .................................................................................................................15 STUDY 1 .......................................................................................................................................17 Research Questions ....................................................................................................................17 Method .......................................................................................................................................18 Participants .............................................................................................................................18 Materials .................................................................................................................................19 Procedure ................................................................................................................................19 Results ........................................................................................................................................20 Note regarding missing data ...................................................................................................20 Confirmatory analyses ............................................................................................................20 Exploratory analyses ...............................................................................................................22 STUDY 2 .......................................................................................................................................24 Method .......................................................................................................................................24 Question ..................................................................................................................................24 Participants .............................................................................................................................24 Materials and procedure .........................................................................................................25 Analyses .....................................................................................................................................26 Data cleaning ..........................................................................................................................26 Behavioral analyses ................................................................................................................27 Some notes on the interpretation of behavioral results .......................................................29 Drift Diffusion Model analyses ..............................................................................................30 Results ........................................................................................................................................31 Behavioral analyses ................................................................................................................31 Perceived threat as a property of the participant .................................................................31 Perceived threat as a property of the stimulus ....................................................................33 Drift Diffusion Model analyses ..............................................................................................33 Summary .................................................................................................................................34 STUDY 3 .......................................................................................................................................36 Method .......................................................................................................................................36 Question ..................................................................................................................................36 Participants .............................................................................................................................36 v Materials and procedure .........................................................................................................36 Analyses ..................................................................................................................................37 Results ........................................................................................................................................37