The Influence of Cognitive Biases on Psychophysiological Vulnerability To
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View metadata, citation and similar papers at core.ac.uk brought to you by CORE provided by University of East Anglia digital repository The influence of cognitive biases on psychophysiological vulnerability to stress Katherine Elizabeth Randall A thesis submitted for the degree of Doctor of Philosophy University of East Anglia, Norwich Norwich Medical School November, 2012 This copy of the thesis has been supplied on condition that anyone who consults it is understood to recognise that its copyright rests with the author and that use of any information derived there from must be in accordance with current UK Copyright Law. In addition, any quotation or extract must include full attribution. i Declaration of Contribution of Work Studies one, five, and six were designed by Katherine Randall (with guidance from supervisors). Studies two and three were collaboratively designed by Katherine Randall and Dr Bristow (Anglia Ruskin University). Study four was collaboratively designed by Katherine Randall, Dr Bristow (Anglia Ruskin University), and Drs Dunn and Brodbeck (Cognition and Brain Sciences Unit, Cambridge). Data collection for studies one, two, five, and six was carried out exclusively by Katherine Randall. Data was collected for study three by Lauren Barrett (undergraduate), with guidance from Katherine Randall and supervision by Dr Bristow. For study four, data collection was started (17 participants of which 5 were excluded from analysis) by Charlie Powell (undergraduate) and completed by Katherine Randall (74 participants of which 5 were excluded from analysis). Studies one, two, four, five, and six were financed by Wellcome Trust Project Grant 074073, which was awarded to Drs Mackintosh, Hoppitt, and Bristow. Study three was financed by Anglia Ruskin University. Studies one, three, four, and five were based at Anglia Ruskin University, Cambridge. Studies two and six were based at the University of East Anglia, Norwich. All saliva assaying was conducted by Katherine Randall at the Tissue Analysis Laboratory, Anglia Ruskin University, Cambridge. All database compilation and statistical analysis was conducted by Katherine Randall. ii Acknowledgements I would like to thank my supervisors, Dr Laura Hoppitt, Dr Laura Jobson, and Dr Bundy Mackintosh, for all their help and direction over the last four years. Thank-you for sticking by me throughout the ups and downs. Thank-you to the Tissue Analysis Laboratory; to Dr Bristow and Katy Parker for introducing me to the World of Spit, and to Flexo (I and II) for enabling (largely) hassle-free saliva analysis. I am grateful to Anglia Ruskin University, especially the Psychology department, for being so accommodating and allowing me access to their students. Massive thanks are, of course, extended to all the participants who gave up their time to help out in my research; for their patience, energy, and interest. I owe thanks to my family for their blind support and encouragement throughout my PhD. Particular recognition is given to my Mum and Dad for providing me with all the opportunities in life that have enabled me to achieve this. Lastly, but by no means least, I want to acknowledge and thank my better half. Matt, as always, you have been my rock. Your countless efforts to keep me grounded, restore my sanity, and motivate me to the end have been second to none. Thank you for all you have done and continue to do to support me. “If you’re not failing every now and again, it’s a sign you’re not doing anything very innovative.” - Woody Allen iii Abstract Individuals who disproportionately attend to negative aspects of a situation (attention bias), or who unduly interpret ambiguity in a negative manner (interpretive bias) report more psychological ill-effects of stress than those with balanced or positively-skewed inclinations. Cognitive Bias Modification (CBM) techniques improve maladaptive biases through implicitly-based association learning, with induced positive biases buffering the future perception of stress. Six experimental studies investigated the next stage of this link to bolster and significantly enhance the clinical potential of CBM; how natural and modified biases influence the biological response to acute stress. Studies 1-3 established reliable protocols associated with using laboratory stress tasks and measuring salivary stress biomarkers. Studies 4-5 investigated links between natural and trained biases on psychological and biological stress responses. Study 6 tested the immediate robustness of CBM training. While psychological and physiological stress responses were initiated, attentional biases were not found to moderate acute biological stress responses. Conversely, interpretive biases were related to the recovery from the acute stress and positive interpretive training led to a faster biological recovery from acute stress in high test-anxious individuals relative to sham training. However, neither bias was found to moderate the psychological response to stress. Further, evidence emerged to caution a more selective use of CBM. Positive interpretive training led to a more negative bias and slower physiological recovery to stress in individuals with low trait anxiety or inherent positive biases. From these results, information processing biases are proposed to have less influence on genuinely stressful events but, instead, govern the extent to which unthreatening situations are perceived as stressful. Consequently, negative biases are hypothesised to cause unnecessary and excessive perceptions of stress, resulting in chronic hyper-activity. Combined CBM-A/I tools are recommended to jointly realign maladaptive biases, enabling an effective, efficient, but transitory physiological response to real stress. iv List of Contents 1.0 CHAPTER ONE - INTRODUCTION................................................................................. 1 1.1 Overview .......................................................................................................................... 1 1.2 Stress ................................................................................................................................ 2 1.2.1 Conceptualising Stress .............................................................................................. 2 1.2.2 Physiological Response to Stress .............................................................................. 4 1.2.3 Capturing the Physiological Stress Response ........................................................... 5 1.2.4 The Perception of Stress ......................................................................................... 10 1.3 Cognitive Biases ............................................................................................................ 11 1.3.1 Attention Biases and Anxiety ................................................................................. 11 1.3.2 Interpretive Biases and Anxiety .............................................................................. 13 1.3.3 Model of Cognitive Bias ......................................................................................... 14 1.3.4 Cognitive Bias and the Physiological Stress Response .......................................... 16 1.4 Cognitive Bias Modification .......................................................................................... 18 1.4.1 The Potential of Bias Modification ......................................................................... 21 1.4.2 CBM and the Physiological Stress Response ......................................................... 22 1.5 Focus and Rationale for this Thesis ............................................................................... 24 2.0 CHAPTER TWO – SALIVA STORAGE AND ANALYSIS ........................................... 27 2.1 Tissue Analysis Laboratory ....................................................................................... 27 2.2 Sample Preparation .................................................................................................... 27 2.3 Cortisol Assay ............................................................................................................ 27 2.4 Alpha Amylase Assay ................................................................................................ 28 v 2.5 Flow Rate ................................................................................................................... 29 2.6 Storage and Destruction of Samples .......................................................................... 29 3.0 CHAPTER THREE: STUDY ONE – On being rejected: Psychological and physiological responses to an acute social rejection task ............................................................................... 30 3.1 Method ........................................................................................................................... 36 3.1.1 Design ..................................................................................................................... 36 3.1.2 Participants .............................................................................................................. 36 3.1.3 Materials ................................................................................................................. 39 3.1.4 Saliva Collection and Analysis ............................................................................... 45 3.1.5 Procedure ................................................................................................................ 46 3.1.6 Data