Graduate Theses and Dissertations Iowa State University Capstones, Theses and Dissertations 2018 Belief perseverance: The staying power of confession evidence Curt More Iowa State University Follow this and additional works at: https://lib.dr.iastate.edu/etd Part of the Social Psychology Commons Recommended Citation More, Curt, "Belief perseverance: The staying power of confession evidence" (2018) Graduate Theses and Dissertations 16421 https://lib.dr.iastate.edu/etd/16421 This Thesis is brought to you for free and open access by the Iowa State University Capstones, Theses and Dissertations at Iowa State University Digital Repository It has been accepted for inclusion in Graduate Theses and Dissertations by an authorized administrator of Iowa State University Digital Repository For more information, please contact digirep@iastate.edu Belief perseverance: The staying power of confession evidence by Curt Craig More A thesis submitted to the graduate faculty in partial fulfillment of the requirements for the degree of MASTER OF SCIENCE Major: Psychology Program of Study Committee: Stephanie Madon, Co-Major Professor Max Guyll, Co-Major Professor Marcus Credé The student author, whose presentation of the scholarship herein was approved by the program of study committee, is solely responsible for the content of this thesis The Graduate College will ensure this thesis is globally accessible and will not permit alterations after a degree is conferred Iowa State University Ames, Iowa 2018 Copyright © Curt Craig More, 2018 All rights reserved ii DEDICATION This thesis is dedicated to my family To my wife, Kimberly More, for her love and encouragement To my parents, Susan More, Bruce More, and Joseph Kitzke, for their support, both emotional and financial To the grandparents I have lost, Kay Brayshaw, Joe Kitzke, and George More, for their unconditional love And to the grandparents I still have, Don Brayshaw, Evona Kitzke, and Pat More, for their unwavering love and belief in me iii TABLE OF CONTENTS Page LIST OF FIGURES v LIST OF TABLES vi ACKNOWLEDGMENTS vii ABSTRACT……………………………… viii CHAPTER INTRODUCTION Error and Bias Belief Perseverance The Power of Confession Evidence Ambiguity Commitment Research Overview and Hypotheses 7 CHAPTER METHOD Power Analysis Participants Design Crime Report Measures Guilt Judgments Perceptions of Impartiality Manipulation Check Attention Check Suspicion Check Scrambled Anagrams Procedures 10 10 10 11 11 12 12 12 12 13 13 14 14 CHAPTER ANALYSES Preliminary Analyses Descriptive Statistics Commitment Manipulation Check Confession Timing Manipulation Check Attention Check Suspicion Check Analytic Plan Model 1: Total Effect of Confession Timing on Phase Guilt Judgments Model 2: Belief Perseverance Effect Path a: Confession Effect 16 16 16 16 16 17 17 17 18 19 19 iv Path b: Judgment Stability Path a × b: Belief Perseverance Path c: Adding Confession Evidence and Procedural Effects Moderation of Belief Perseverance by Commitment Main Analyses Model 1: Total Effect of Confession Timing Model 2: Belief Perseverance Effect Path a: Confession Effect Path b: Judgment Stability Path a × b: Belief Perseverance Path c: Adding Confession Evidence and Procedural Effects Path a × b + c: Total Effect of Confession Evidence Moderation of Belief Perseverance by Commitment 20 20 20 22 22 22 23 24 24 25 25 25 26 CHAPTER DISCUSSION Belief Perseverance Commitment Accountability Limitations Conclusion 27 27 29 29 30 31 REFERENCES 33 APPENDIX A PHASE CRIME REPORT: CONFESSION EARLY 45 APPENDIX B PHASE CRIME REPORT: CONFESSION LATE 47 APPENDIX C PHASE CRIME REPORT 48 APPENDIX D GUILT JUDGMENTS 52 APPENDIX E PERCEPTIONS OF IMPARTIALITY 53 APPENDIX F MANIPULATION CHECK 54 APPENDIX G ATTENTION CHECK 55 APPENDIX H SUSPICION CHECK 56 APPENDIX I SCRAMBLED ANAGRAMS 57 APPENDIX J INSTITUTIONAL REVIEW BOARD APPROVAL FORM 58 v LIST OF FIGURES Page Figure Participant Verdicts by Condition and Phase 37 Figure Model 1: Examination of Total Effects 38 Figure Model 2: Mediated Model Examining Indirect Effects 39 vi LIST OF TABLES Page Table Experimental Design 40 Table Descriptive Statistics 41 Table Correlations 42 Table Correlations by Commitment Condition 43 Table Model Path Coefficients 44 vii ACKNOWLEDGMENTS I would like to thank some of the incredible mentors I have encountered leading up to this thesis To Dr Leora Dahl for inspiring me to study forensic psychology rather than English To Dr Linda Hatt and the late Dr Claire Budgen for the opportunity to be a part of a research team as an undergraduate To Dr Michael Woodworth for his mentorship of my honours thesis To Dr Jan Cioe for his friendship and guidance on how to be a better student, a better teacher, and a better person To Dr Marcus Credé and Dr Gary Wells for their advice throughout the crafting of this thesis And finally to my co-advisors, Dr Max Guyll and Dr Stephanie Madon, for their constant support and encouragement, without which this thesis would not have been possible viii ABSTRACT This research examined whether a criminal confession causes people to discount subsequently encountered exculpatory evidence Participants (N = 238) read a crime report across two phases and judged a suspect's guilt after each phase In phase 1, the crime report presented circumstantial evidence indicative of the suspect's guilt In phase 2, exculpatory evidence indicative of the suspect's innocence was added The crime report manipulated whether participants received confession evidence during phase (confession–early) or phase (confession–late) In addition, some participants publicly committed to their phase guilt judgments prior to receiving the crime report in phase (high commitment), whereas others did not (low commitment) Results provided some support for the hypothesis that a confession biases the way that people use subsequently encountered exculpatory evidence to judge a suspect’s guilt; under conditions of low commitment, participants more often rendered guilty verdicts in the confession–early conditions than the confession–late conditions The results are discussed in terms of police investigator and juror decision-making CHAPTER INTRODUCTION It is well-established that a confession, even a false one, is a highly incriminating form of evidence (Kassin, 2008; Leo & Drizin, 2010) Confession evidence is more powerful than eyewitness and character testimony (Kassin & Neumann, 1997), and can even attenuate the formidable power of DNA evidence under some conditions (Appleby & Kassin, 2016) Jurors will sometimes convict defendants on the basis of confession evidence alone, and they not appropriately discount confessions that they believed were obtained under duress or that were ruled inadmissible (Kassin et al., 2010; Kassin & Sukel, 1997; Smalarz, Madon, Yang, Guyll, & Buck, 2016) Not surprisingly, jury conviction rates for false confessors are very high, ranging from 73% – 81% (Drizin & Leo, 2004; Ofshe & Leo, 1997) The power of confession evidence stems, in large part, from the widespread belief that suspects, motivated by self-interest, would not confess to crimes that they did not commit unless subjected to physical abuse or torture (Kassin & Wrightsman, 1981) However, psychological research findings and proven false confession cases reveal this belief to be a misconception Innocent suspects sometimes confess to crimes that they did not commit In fact, false confessions are a leading cause of wrongful convictions in the United States, contributing to the convictions of nearly 28% of defendants who were later exonerated by DNA evidence (“DNA Exonerations Nationwide,” 2016) Although the widespread belief that false confessions only arise under egregious circumstances is not true, it hints at the way that error and bias may contribute to the power of confession evidence That is, once people learn that a suspect has confessed, they may develop such a strong belief in the suspect's guilt that they fail to appropriately adjust their guilt judgments in response to subsequently encountered evidence that points to the suspect's