Running head: A RE-EXAMINATION OF EYEWITNESS MEMORY PHENOMENA A Re-examination of Eyewitness Memory Phenomena Using Receiver Operating Characteristic Analysis and Confidence- Accuracy Characteristic Analysis Travis Morgan Seale-Carlisle Thesis submitted in fulfilment of the degree of Doctor of Philosophy Department of Psychology Royal Holloway, University of London A RE-EXAMINATION OF EYEWITNESS MEMORY PHENOMENA Abstract Eyewitness identification research is focused on investigating the factors that affect the eyewitnesses’ ability to accurately identify the perpetrator from a lineup. A lineup consists of the police suspect and several other individuals who resemble the perpetrator, but are known to be innocent (called fillers). Several decades of research continue to have a growing impact on criminal justice systems throughout the world, most notably in the US, by informing public policy and informing the court (i.e. judges and jurors) through expert testimony. Efforts to shape public policy have been directed at improving fundamental aspects of the identification process with the goal to implement procedures that maximize discriminability – the ability to distinguish innocent from guilty suspects. Yet, poor measures of discriminability have resulted in many US jurisdictions implementing substandard procedures that may actually reduce discriminability. In court, factors that reduce discriminability are believed by many experts to reduce the reliability of an eyewitness identification – the accuracy of a suspect identification admitted as evidence in court. However, discriminability and reliability are two separate measures of eyewitness identification “accuracy.” That is, an eyewitness may have poor discriminability, but may nonetheless make a reliable identification from a lineup. To critically assess this issue, I have re-examined several eyewitness memory phenomena including the sequential superiority effect (Chapter 3), the verbal overshadowing effect (Chapter 4), and the weapon focus effect (Chapter 5) using two analytic techniques recently introduced to the eyewitness identification field that measure discriminability and the reliability of a suspect identification: receiver operating characteristic analysis and confidence-accuracy characteristic analysis, respectively. Together, this research highlights the importance of distinguishing between discriminability and reliability. Appreciating this distinction can help inform policymakers of procedures that boost discriminability and can help inform the court of the reliability of a suspect identification. 2 A RE-EXAMINATION OF EYEWITNESS MEMORY PHENOMENA Declaration of Authorship I, Travis M. Seale-Carlisle, hereby declare that this work was carried out in accordance with the Regulations of the University of London. I declare that this submission is my own work, and does not represent the work of others, published or unpublished, except where duly acknowledged in the text. No part of this thesis has been submitted for a higher degree at another university or institution. Signed ______________ Dated _______________ 3 A RE-EXAMINATION OF EYEWITNESS MEMORY PHENOMENA Acknowledgements I would first like to thank my supervisor, Dr. Laura Mickes. You have helped me grow as a researcher and as a person over the last eight years. I cherish our relationship. I know that without your guidance, I would not have made it this far. I sincerely thank you for supervising me. I would also like to thank my family for all of their support throughout the completion of this thesis. To my Dad, thank you for your overwhelming support. I know that you will agree that my future is “so bright” that I need sunglasses (true dat, double true). Love you Dad. To my Mom, you have continued to support me through thick and thin. I love you. You are the best mom in the world. I would especially like to thank my brother, Justin Seale-Carlisle, for always being there for me and continuing to be someone who I look up to and admire. You deserve everything in life. I can’t even imagine where I would be without you. You’re an amazing brother. Love you bruv! I would also like to thank Gurpreet. You are my partner through and through. I love you, even though you are not very good at FIFA and you get scared easily. I look forward to our future together. I’m proud of you and greatly admire your strength and charm. You can always make me laugh and smile. Lastly, I would like to thank all of my friends in the Psychology Department for being kind, resourceful, and thoughtful throughout my time here. Science is hard, but each of you helped to make it a bit easier. 4 A RE-EXAMINATION OF EYEWITNESS MEMORY PHENOMENA Table of Contents List of Tables ........................................................................................................ 10 List of Figures ...................................................................................................... 11 Chapter 1: Introduction ........................................................................................ 13 The Basic Identification Procedure ............................................................ 13 Consequences of a False ID .............................................................. 14 Consequences of a Miss .................................................................... 14 Standard Eyewitness Identification Experiment ............................... 14 Assisting the Criminal Justice System: Experts in Court ........................... 15 Should Eyewitness Experts Testify? ................................................. 16 Eyewitness Expert in Court ............................................................... 16 Measuring the Reliability of a Suspect Identification ....................... 17 Assisting the Criminal Justice System: Consultants to Policymakers ........ 24 Review of System Variable Research ................................................ 25 Misuse of the Diagnosticity Ratio ..................................................... 26 Receiver Operating Characteristic Analysis ...................................... 29 Signal-Detection Theory ................................................................... 33 Diagnostic-Feature-Detection Hypothesis ........................................ 39 Preview of Upcoming Chapters .................................................................. 39 Chapter 2: General Methods ................................................................................ 40 General Procedure ...................................................................................... 40 Calculating Correct ID, False ID, and Filler ID rates. ................................ 41 Correct ID Rate ................................................................................. 41 False ID Rate ..................................................................................... 41 Filler ID Rate ..................................................................................... 42 Receiver Operating Characteristic Analysis ............................................... 42 Statistically Comparing pAUC Values .............................................. 43 5 A RE-EXAMINATION OF EYEWITNESS MEMORY PHENOMENA Estimating Lineup Discriminability ........................................................... 43 Testing for Significance .................................................................... 47 Comparing d′ and pAUC ................................................................... 47 Confidence-Accuracy Characteristic Analysis ........................................... 47 Suspect ID Accuracy and Prior Probability....................................... 48 Computing CAC Standard Errors ..................................................... 49 Chapter 3: The US Lineup Outperform UK Lineup ............................................ 50 UK Lineup .................................................................................................. 50 US Lineup ................................................................................................... 51 US Lineup vs. UK Lineup Predictions ....................................................... 52 Moving vs. Static Images .................................................................. 53 Multiple Laps vs. One Viewing ......................................................... 54 Nine vs. Six Lineup Members ........................................................... 56 US vs. UK Predictions Revisited ...................................................... 59 Confidence-accuracy Characteristic Analysis ............................................ 59 Experiment 1 and 2 ..................................................................................... 60 Methods ............................................................................................. 60 Results ............................................................................................... 61 General Discussion ............................................................................ 67 Chapter 4: The Effect of Descriptions on Discriminability and Reliability ......... 69 Replicating the Verbal Overshadowing Effect ............................................ 69 Theoretical Implications of Verbal Overshadowing .......................... 70 Content Accounts of Verbal Overshadowing .............................................. 70 Recoding Interference ....................................................................... 70 Retrieval-based Interference ............................................................