THE ROLE OF ORBITAL FRONTAL CORTEX IN EMOTIONAL REASONING HOI LING (ELAINE) LAM A THESIS SUBMITTED TO THE FACULTY OF GRADUATE STUDIES IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF ARTS GRADUATE PROGRAM IN PSYCHOLOGY YORK UNIVERISTY TORONTO, ONTARIO AUGUST 2012 © Hoi Ling (Elaine) Lam, 2012 Library and Archives Bibliotheque et Canada Archives Canada Published Heritage Direction du 1+1 Branch Patrimoine de I'edition 395 Wellington Street 395, rue Wellington Ottawa ON K1A0N4 Ottawa ON K1A 0N4 Canada Canada Your file Votre reference ISBN: 978-0-494-91745-9 Our file Notre reference ISBN: 978-0-494-91745-9 NOTICE: AVIS: The author has granted a non­ L'auteur a accorde une licence non exclusive exclusive license allowing Library and permettant a la Bibliotheque et Archives Archives Canada to reproduce, Canada de reproduire, publier, archiver, publish, archive, preserve, conserve, sauvegarder, conserver, transmettre au public communicate to the public by par telecommunication ou par I'lnternet, preter, telecommunication or on the Internet, distribuer et vendre des theses partout dans le loan, distrbute and sell theses monde, a des fins commerciales ou autres, sur worldwide, for commercial or non­ support microforme, papier, electronique et/ou commercial purposes, in microform, autres formats. paper, electronic and/or any other formats. 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Canada Abstract While it is widely accepted that emotions interact with and affect logical reasoning, very few studies, have explored, the basis of this interaction, particularly at the neural level. Goel and his colleagues’ (Goel & Dolan, 2003) recent study provided initial evidence for differential roles of the dorsolateral prefrontal and ventral medial prefrontal cortex in reasoning about emotionally neutral and emotionally salient material,, respectively. The present study further examined the role of orbital frontal cortex in emotional reasoning. We tested patients with unilateral focal lesions in orbital frontal cortex (i.e., OFC - BA 10 and 11), patients with lesions in parietal cortex,, and normal participants as they made logical inference on emotionally salient and neutral syllogisms. We found only patients with OFC to be impaired in reasoning about emotional material but not in reasoning about neutral material. The subsequent analyses revealed that this impairment was driven by the incongruent syllogisms. The fact that the same patients were reasoning well in the neutral incongruent trials suggested it was the presence of emotion that interrupted the conflict detection system. These results consolidated the findings of the imaging study by demonstrating the necessity of OFC for reasoning with emotional material. This suggests OFC plays a crucial role in processing or abstracting emotion from the materials before passing on to the logical reasoning engine. Table of Contents Abstract .......................................................................................................................... ii Table of Contents ......................................................................................................... iii List of Tables ................................................................................ iv List of Figures .................................................................................................................. v Introduction .....................................................................................................................1 Method .......................................................................................................................... 20 Results .......................................................................................................................... 26 Discussion .................................................................................................................... 34 Conclusion ................................................................................................................... 39 References ................................................................. 41 Appendices ..................................................................................................................46 Appendix A: List of the syllogisms ................................................................ 46 iv List of Tables Table 1: Characteristics of Patient and Normal Control Samples ......................... 22 Table 2: Samples of Syllogisms ..................................................................................23 List of Tables Figure 1: Overlays of 17 patients with lesions in the left and right orbital frontal cortex.............................................................................................................................21 Figure 1: Overlays of 12 patients with lesions in the parietal lobe 21 Figure 3; The interaction between groups and content in accuracy ............................................................................................................................................ 27 Figure 4: Group’s reaction time as a function of content ........................................29 Figure 5a: Group’s accuracy rate on congruent trials as a function of content....30 Figure 5b: Group’s accuracy rate on incongruent trials as a function of content .........................................................................................................................................30 Figure 6a: Group’s reaction time on congruent trials as a function of content ........................................................................................................................................ 31 Figure 6b: Group’s reaction time on congruent trials as a function of content ........................................................................................................................................31 Figure 7: Group’s believability rating on incongruent trials as a function of content Figure 8: The total number of trials each group rated as a function of emotionality in emotional incongruent trials .................................................................................... 34 Role of Orbital Frontal Cortex on Emotional Reasoning 1 Introduction What is logical reasoning? Let us consider the following argument: Argument 1 All Pad users are Mac supporters No Mac supporters are PC users Therefore no PC users are iPad users Logical reasoning is a process we engage in to draw conclusions (i.e., the third sentence) from the given information (i.e., the premises - the first two sentences). Argument 1 above is also referred to as deductive reasoning. Deductive reasoning often is held as a prime example of human intellectual ability and a key method of gaining knowledge. In the simplest terms, deductive reasoning starts with a general case and deduces to specific instances. It is a closed system in which the conclusions are contained within the premises and are logically independent of the content of the propositions. A deductive argument is valid if the conclusion follows necessarily from the premises. Argument formats, such as syllogistic reasoning (e.g., Argument 1) and conditional reasoning (e.g., If it rains, I get wet. It is raining, therefore I am getting wet), has been used to explore and examine the ways in which people reason, and how and why people make mistakes. Reason, Emotion, and Belief Role of Orbital Frontal Cortex on Emotional Reasoning 2 It is clear that the process of logical reasoning is affected by a number of factors, such as our emotional states and our beliefs. For example, one day I was shopping for vitamins for my son, two brands contained the vitamins I was looking for with exactly the same ingredients. However, one brand was 2/3 of the price of the other brand. As a smart and rational customer, it made perfect sense to get the cheaper one with the same ingredients. However instead of following my rational sense, I decided to buy the more expensive brand because I believed that the more well-known brand was more reliable. In addition to belief, emotion also plays a crucial role in our daily reasoning, even to people who are experts in logical reasoning. My supervisor once shared with us his own experience as follows. He had a broken appliance and found a repair store located 30-45 minutes away from his home. He was told that it would be ready to pick up anytime in the morning of the following day. He dropped by the store in the morning expecting to pick up his appliance as agreed. However, he was told that it was not ready and that he had to come back in the afternoon. In addition to that, the appliance appeared