AN INVESTIGATION OF THE ROLE OF CONFIRMATION BIAS IN THE EVALUATION OF INFORMAL REASONING FALLACIES A Dissertation Submitted to the Temple University Graduate Board in Partial Fulfillment of the Requirements for the Degree DOCTOR OF PHILOSOPHY by Jay Tarnoff August, 2010 Examining Committee Members: Frank Farley, Advisory Chair, School Psychology Catherine Fiorello, School Psychology Erin Rotheram-Fuller, School Psychology Joseph DuCette, Educational Psychology Joseph Rosenfeld, School Psychology © by Jay Tarnoff 2010 All Rights Reserved ii ABSTRACT AN INVESTIGATION OF THE ROLE OF CONFIRMATION BIAS IN THE EVALUATION OF INFORMAL REASONING FALLACIES by Jay Tarnoff Doctor of Philosophy Temple University, 2010 Major Advisor: Dr. Frank Farley A total of 168 undergraduate students at Temple University provided a measure of their prior beliefs and measures of attitude strength on three topics and then attempted to identify and explain informal reasoning fallacies based on the same topics. Contrary to the hypothesized predictions, prior beliefs and measures of attitude strength did not have a significant effect on participants’ ability to accept informal reasoning fallacies consistent with their beliefs based on that topic, although agreement with the topic demonstrated modest effects. Furthermore, this research demonstrated that participants have significant difficulty identifying and explaining informal logical fallacies. Ability to identify and explain one informal fallacy is not a significant predictor of the ability to identify and explain other fallacies. Also, ability to identify and explain one fallacy in a topic is a poor predictor of the ability to identify and explain that fallacy in another topic. This research indicates that formal fallacy syllogism scores were the best predictor of the ability to identify and explain informal logical fallacies, and that agreement with the topic and willingness to act on those beliefs demonstrated modest effects. Consistent with studies on dual-processing theory, in informal logic the individual is forced to examine the information presented in the statement and the iii structure of the statement and then relate it to their prior opinions and attitudes about the topic, and therefore, the acceptance of the fallacy is a matter of motivated reasoning bias or self-deception instead of an error in analytical reasoning. Informal reasoning fallacies represented an error in judgment, or a misunderstanding of the validity of an argument. Practical implications for school psychologists, limitations of this research, and directions for future research were discussed. iv ACKNOWLEDGEMENTS I would first like to express my gratitude to Drs. Farley, Fiorello, Rotheram-Fuller, Ducette, and Rosenfeld for encouraging me, supporting me, and always being gracious with their time and commitment to helping me throughout the dissertation process. I wanted to also thank my dissertation team for allowing me to pursue a research area that match so well with my scientific skepticism interests. A special thank you goes to James “The Amazing” Randi and the James Randi Educational Foundation (JREF) staff who supported my dissertation with the generous 2010 Academic Scholarship for Critical Thinking. I thank Dr. Boyer for encouraging me to pursue informal reasoning as a dissertation topic after one of my presentations in her class. Dr. Boyer was able to see my enthusiasm for the subject and encouraged me to explore how this interest intersected with school psychology. I wanted to acknowledge Laura Katz and Maureen Zdanis for their help in scoring the student responses in the fallacy explanation task. We were all able to still smile after the long hours I pushed these ladies to get the data scored. My thanks go to all of the professors and teaching assistants who allowed me to solicit students in their classes and to the students who took their time to participate in this study. I understand the desire to enjoy the summer days after an undergraduate class, but this dissertation could not have been completed without your help. I wanted to thank my family for all of their love and support throughout my education. You were there through my triumphs and hardships, believing in me when I doubted myself and always giving me the strength to move forward. Lastly, my deepest thanks go to my very-soon-to-be wife, Lauren. You were always first to offer up your time as a practice test participant in any cognitive assessment, were always understanding with v providing me as much time as I needed to complete my graduate work, and were the best comprehensive test “study-buddy” I could ever imagine. The distinction, my love, and the dedication of this work go to you. vi TABLE OF CONTENTS Page ABSTRACT......................................................................................................................................... iii ACKNOWLEDGEMENTS ............................................................................................................vi LIST OF TABLES ............................................................................................................................. ix LIST OF FIGURES............................................................................................................................ x CHAPTER 1. INTRODUCTION AND LITERATURE REVIEW..................................................... 1 Definitions ................................................................................................................. 1 Research Problem..................................................................................................... 2 Purpose of this Study ............................................................................................... 9 Research Hypotheses .............................................................................................11 2. LITERATURE REVIEW..................................................................................................14 Argumentation ........................................................................................................15 Fallacies in Reasoning and Logic..........................................................................17 The Dual-Process Model of Cognition ...............................................................19 Confirmation Bias: Belief Bias..............................................................................21 Dual-Processing Theory in Reasoning ................................................................24 Belief Bias and Formal Logic................................................................................27 Prior Beliefs and Informal Logic..........................................................................34 Developmental Trends in Critical Thinking and Argumentation....................38 Epistemological Understanding............................................................................40 Informal Reasoning Fallacies ................................................................................43 Differentiating Explanation and Evidence in Informal Reasoning.................51 The Biasing Effect of Motivated Reasoning.......................................................55 Prior Beliefs and Attitude Strength......................................................................56 Informal Reasoning and Its Relevance to School Psychology.........................62 Research Hypotheses .............................................................................................64 3. METHODS...........................................................................................................................66 Participants ..............................................................................................................66 Settings .....................................................................................................................67 Materials and Variables ..........................................................................................67 Informal Fallacy Task.............................................................................................67 Personal Attitudes Task .........................................................................................72 Formal Logic Syllogism Task................................................................................74 Demographics Questionnaire ...............................................................................75 Data Analysis...........................................................................................................77 4. RESULTS..............................................................................................................................80 Attitudes Measures .................................................................................................80 Informal Fallacy Identification .............................................................................85 Informal Fallacy Explanation................................................................................98 5. DISCUSSION ....................................................................................................................110 Purpose of the Study............................................................................................110 Informal Fallacy Identification and Explanation .............................................110 vii Variables Predicting Identification and Explanation.......................................111