Measurement Issues and the Role of Cognitive Biases in Conspiracist Ideation Robert A. Brotherton Department of Psychology Goldsmiths, University of London A thesis submitted for the degree of Doctor of Philosophy at Goldsmiths, University of London in October 2013 Statement of Originality This thesis represents my own original work towards this research degree and contains no material which has been previously submitted for a degree at this University or any other institution, except where due acknowledgement is made. Robert A. Brotherton 2 Acknowledgements My sincerest thanks go to everyone who helped make this thesis what it is: To my supervisors Chris French (not only the best mentor I could hope for, but a good friend as well), Tomas Chamorro-Premuzic (for guiding the first half of this research), and Alan Pickering (for coming on board later, but having no less input for it). To Pam Heaton and Elisabeth Hill for deciding that this work might be worth funding, and to the Economic and Social Research council for agreeing. To Karen Douglas, who is responsible for my interest in the psychology of conspiracy theories in the first place. To Mark Williams, James Moore, Adrian Furnham, Paul Rogers, Patrick Leman, Rob Teszka, and various peer-reviewers for valuable help, advice, and constructive criticism. Most of all, for unending support and encouragement, to my parents, Ann and Bob, and my partner Lindsay. And, last but not least, to everyone who participated in this research – particularly those who suspected me of being a government shill. This work was supported by the Economic and Social Research Council [grant number ES/I90249X] 3 Related Publications Some of the work contained within this dissertation has appeared in the following publications. A version of the section of Chapter 1 concerning the definition of ‗conspiracy theory‘ was published in: Brotherton, R. (2013). Towards a definition of ―conspiracy theory.‖ PsyPAG Quarterly, 88(3), 9–14. A version of Chapter 2, concerning the development of a novel measure of conspiracist ideation, was published in: Brotherton, R., French, C. C., & Pickering, A. D. (2013). Measuring belief in conspiracy theories: The generic conspiracist beliefs scale. Frontiers in Personality Science and Individual Differences, 4: 279. doi:10.3389/fpsyg.2013.00279 A version of Study 5b, concerning conspiracist ideation and susceptibility to the conjunction fallacy, has been accepted for publication in: Brotherton, R., & French, C. C. (in press). Belief in conspiracy theories and susceptibility to the conjunction fallacy. Applied Cognitive Psychology. 4 Abstract Conspiracy theories are a prominent feature of contemporary culture, and can have far-reaching consequences for believers and disbelievers alike. Until recently, however, relatively little research has examined the psychological origins of conspiracist beliefs. A growing amount of research has now begun to reveal the personality, motivational, cognitive, and social factors associated with belief in conspiracy theories. The current thesis aims to contribute to this literature in two main ways. First, the existing literature is limited by the lack of a validated measurement device. Aiming to address this need, Chapter 2 details the creation of a novel measure of conspiracist ideation, the Generic Conspiracist Beliefs (GCB) scale, from item selection (Study 1) through to psychometric validation (Studies 2, 3, and 4). This measure assesses generic conspiracist ideation, therefore offering greater practical utility and theoretical validity than existing measures which assess endorsement of conspiracy theories based on specific world events. Second, the literature may benefit from incorporating conspiracism into the wider theoretical framework of anomalistic psychology. Chapters 3 and 4 employ the newly created GCB to investigate the role of representativeness heuristics – according to which claims are judged plausible to the extent that they subjectively appear typical of events in general – in conspiracist ideation. Study 5a predicted that the proportionality bias would influence novel conspiracist attributions; however, the data did not support this hypothesis. Study 5b predicted that susceptibility to the conjunction fallacy would be associated with conspiracist ideation. This hypothesis was supported. Finally, Chapter 4 predicted that conspiracist ideation would be associated with biased attributions of intentionality. Support for this hypothesis was mixed; the findings suggest that an inferential bias towards attributions of intentionality predicts conspiracist ideation, but a perceptual bias does not. In sum, the findings suggest that conspiracist beliefs may be a product, in part, of certain representativeness biases. 5 Table of Contents Statement of Originality 2 Acknowledgements 3 Related Publications 4 Abstract 5 Chapter 1. General Introduction Overview 12 A brief introduction to conspiracy theories 15 The prevalence of conspiracy theories 15 The consequences of conspiracy theories 18 Towards a working definition of ‗conspiracy theory‘ 20 The characteristics of conspiracy theories 21 Definition summary 26 Review of the psychological literature 27 Associations between conspiracy beliefs 27 Sociodemographic correlates 31 Individual differences 33 Cognitive biases and heuristics 39 Summary of the literature 46 Limitations and research objectives 47 Research programme 49 Chapter 2. Measuring Belief in Conspiracy Theories: The Creation of a Generic Conspiracist Beliefs Scale Introduction 52 Previous approaches towards measuring conspiracist beliefs 53 Measuring generic conspiracist beliefs 55 Overview of the present studies 56 Study 1: Identifying essential facets of conspiracism 57 Method 57 Results 58 Discussion 64 Study 2: Factor structure, reliability & criterion validity 64 Method 65 6 Table of Contents (continued) Results 66 Discussion 71 Study 3: Convergent validity and additional evidence of criterion-related validity 72 Method 72 Results 74 Discussion 75 Study 4: Discriminant validity 75 Method 76 Results 77 Discussion 78 General discussion 79 Summary and conclusions 82 Chapter 3. Conspiracy Theories and Judgements by Representativeness: The Proportionality Bias and the Conjunction Fallacy Introduction 84 The representativeness heuristic 84 Representativeness and judgements of causality 86 Representativeness and anomalous beliefs 87 Overview of the current studies 88 Study 5a: Belief in conspiracy theories and the proportionality bias 90 Introduction 90 Method 92 Results 95 Discussion 97 Study 5b: Belief in conspiracy theories and susceptibility to the conjunction fallacy 100 Introduction 100 Method 103 Results 105 Discussion 107 General discussion 110 7 Table of Contents (continued) Chapter 4. Representativeness Continued: Conspiracist Ideation and Judgements of Intentionality Introduction 112 Inferring intent 112 Overattribution of intentionality 114 Intentionality and conspiracy theories 116 Overview of studies 118 Study 5c: Conspiracist ideation and inferences of intentionality 119 Method 119 Results 121 Discussion 124 Study 6: Conspiracist ideation and perceived intentionality 125 Method 125 Results 127 Discussion 129 Study 7: Individual differences in anthropomorphisation 130 Method 131 Results 132 Discussion 133 Study 8: Associations between anthropomorphisation and intentional inferences 133 Method 133 Results 135 Discussion 136 General discussion 138 Summary and conclusions 142 Chapter 5. General Discussion Purposes and key findings of the present research 144 Background and rationale 144 Key findings 147 Summary and implications 150 Research limitations 153 Future directions 157 8 Table of Contents (continued) Conclusion 160 References 161 Appendix 2.1. Item-loadings for the alternative 6-factor solution in Study 1 182 Appendix 2.2. GCB scale instructions and item wording 185 Appendix 3.1. Proportionality bias instructions and vignette wording 186 Appendix 3.2. Wording of novel conspiracy-themed conjunction items 187 9 List of Tables 2.1. Comparison of results of EFA Eigenvalues with PA Eigenvalues. 2.2. Conspiracist Beliefs Scale (long-form) items and factor loadings. 2.3. Correlations between factor scores and overall Conspiracist Beliefs Scale (long- form) score. 2.4. GCB scale items and standardised factor loadings obtained with exploratory factor analysis. 2.5. Item standardised factor loadings obtained with confirmatory factor analysis. 2.6. Correlations between latent variables. 2.7. Multicollinearity diagnostics for regression model. 2.8. Results of multiple regression analysis with GCB factor scores predicting 9/11 conspiracist beliefs. 2.9. Means, standard deviations, and interscale correlations for Study 3. 2.10. Means, standard deviations, and interscale correlations for Study 4. 3.1. Mean ratings for likelihood of statements being true (standard deviations in parentheses), and MANOVA results. 4.1. Results of multiple regression with intentional inferences and anthropomorphism predicting conspiracist ideation. 10 List of Figures 3.1. Average number of conjunction fallacy errors for each item type by belief group. 4.1. Scatterplot of number of inferences of intentionality against conspiracist ideation (GCB scores). 4.2. Average number of inferences of intentionality among quartile groups derived from GCB scores (lowest to highest). 4.3. Schematic illustration of key-pressing apparatus. 4.4. Scatterplot of GCB scores against number of intentional attributions. 4.5. Scatterplot of anthropomorphism (IDAQ