The effect of trait anxiety on the generalisation of fear acquisition and extinction Hon Ki Wong Bachelor of Psychology (Honours) Submitted in partial fulfilment of the requirements for the degree of Doctor of Philosophy November 2018 School of Psychology Faculty of Science Thesis/Dissertation Sheet Surname/Family Name : Wong Given Name/s : Hon Ki (Alex) Abbreviation for degree as give in the University calendar : BCom / BSc(Hons) Faculty : Science School : Psychology The effect of trait anxiety on the generalisation of fear acquisition and Thesis Title : extinction Abstract 350 words maximum: Fear generalisation refers to the spread of fear to novel situations. Recent evidence has suggested that over-generalisation of fear is a pathogenic marker of anxiety disorders. Given that trait anxiety has been widely accepted as a vulnerability factor for developing an anxiety disorder, the current thesis aimed to examine whether trait anxious individuals show over-generalisation of fear like their clinical counterparts. Using a continuous perceptual dimension, the first experiment (Chapter 5) identified various generalisation gradients, which aligned logically with participants’ reported rules. Trait anxious individuals showed over-generalisation of fear to the novel test stimuli, but this pattern was only observed among those who failed to identify a clear rule. The following experiments (Chapter 6) further examined fear generalisation to objects that were conceptually related to the threat cues. Trait anxious individuals did not show more fear to novel exemplars that had clear categorical membership and therefore clear threat value. However, they showed more fear to novel exemplars that could be classified in both threat and safe categories, that is, exemplars with ambiguous threat value. The results supported the notion of threat appraisal bias under ambiguous threat among trait anxious individuals. The experiments in Chapter 7 examined the effect of trait anxiety on the generalisation of extinction learning along a blue- green stimulus dimension. Participants who received a generalisation stimulus (GS) in extinction showed an increase in conditioned fear to the original conditioned stimulus (CS) or to another novel GS in test. Conversely, this pattern was not found in those who received standard extinction with the CS. No trait anxiety effect was observed in the generalisation of extinction learning, however, trait anxious individuals showed slower fear extinction to the CS, but not to a GS. In summary, the present work suggests that over-generalisation of fear and resistance in fear extinction may be a special case of the more general principle that trait anxiety is associated with excessive threat appraisal under conditions of ambiguity. It also highlights the importance of higher-order cognitive processes in human fear generalisation. The current findings have important clinical implications. Specifically, they suggest the importance of targeting cognitive reappraisal and strategies that reduce situational ambiguity in clinical treatments. Declaration relating to disposition of project thesis/dissertation I hereby grant to the University of New South Wales or its agents the right to archive and to make available my thesis or dissertation in whole or in part in the University libraries in all forms of media, now or here after known, subject to the provisions of the Copyright Act 1968. I retain all property rights, such as patent rights. 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Publications can be used in their thesis in lieu of a Chapter if: • The student contributed greater than 50% of the content in the publication and is the “primary author”, ie. the student was responsible primarily for the planning, execution and preparation of the work for publication • The student has approval to include the publication in their thesis in lieu of a Chapter from their supervisor and Postgraduate Coordinator. • The publication is not subject to any obligations or contractual agreements with a third party that would constrain its inclusion in the thesis Please indicate whether this thesis contains published material or not. ☐ This thesis contains no publications, either published or submitted for publication Some of the work described in this thesis has been published and it has been ☐ documented in the relevant Chapters with acknowledgement This thesis has publications (either published or submitted for publication) ☐ incorporated into it in lieu of a chapter and the details are presented below CANDIDATE’S DECLARATION I declare that: • I have complied with the Thesis Examination Procedure • where I have used a publication in lieu of a Chapter, the listed publication(s) below meet(s) the requirements to be included in the thesis. Name Signature Date (dd/mm/yy) COPYRIGHT STATEMENT ‘I hereby grant the University of New South Wales or its agents the right to archive and to make available my thesis or dissertation in whole or part in the University libraries in all forms of media, now or here after known, subject to the provisions of the Copyright Act 1968. I retain all proprietary rights, such as patent rights. I also retain the right to use in future works (such as articles or books) all or part of this thesis or dissertation. I also authorise University Microfilms to use the 350 word abstract of my thesis in Dissertation Abstract International (this is applicable to doctoral theses only). I have either used no substantial portions of copyright material in my thesis or I have obtained permission to use copyright material; where permission has not been granted I have applied/will apply for a partial restriction of the digital copy of my thesis or dissertation.' Signed ……………………………………………........................... Date ……………………………………………........................... AUTHENTICITY STATEMENT ‘I certify that the Library deposit digital copy is a direct equivalent of the final officially approved version of my thesis. No emendation of content has occurred and if there are any minor variations in formatting, they are the result of the conversion to digital format.’ Signed ……………………………………………........................... Date ……………………………………………........................... i Acknowledgements First and foremost, I would like to express my deepest gratitude to my PhD advisor Prof. Peter Lovibond. Peter, I still remember our first meeting, where you spent two hours introducing the literature of associative learning to me. It was your enthusiasm and unique insight into research that inspired me to pursue a career in research. During my PhD, you were never too busy to give me advice – whenever I popped my head into your office (without an appointment), you always greeted me with a smile and took time to answer all my questions! I especially appreciate your effort to squeeze time out for us from your extremely busy schedule when you took on the role of Acting Dean. Your advice was always constructive - my knowledge in scientific research grew a bit more every time I left your office. Your concern for your students’ future career is also noteworthy – I particularly enjoyed the conversations when you explained how the academic world works. I have often heard that pursuing a PhD is a draining experience; however, my experience in the Lovibond lab was enjoyable, intellectually stimulating and fun. I would also like to thank my secondary advisor Prof. Brett Hayes. Brett, you were always just an email away, and thank you for all the vital advices for my thesis! I would also like to thank the various members in the Lovibond lab: To Michelle Satkunarajah: You were the first lab member I met when I joined the Lovibond lab. At first, you seemed like a quiet and shy girl – I was never so wrong. However,