| Abstract No.: | A-G1199 |
| Country: | Canada |
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| Title: | THE SOMATIC MARKER HYPOTHESIS AND DECISION MAKING IN NORMAL POPULATION: SOLVING THE ASYMMETRICAL MOTIVATIONAL SYSTEMS PUZZLE |
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| Authors/Affiliations: | 1 Remi Desmeules*; 2 Antoine Bechara; 1 Laurette Dubé;
1 McGill University, Montreal, QC, Canada; 2 University of Southern California, USA.
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| Content: | Objectives: Numerous studies using populations with brain lesions provided support for the somatic marker hypothesis (SMH), a theory positing that a network of brain structures, typically associated with emotion, play an important role in human decision making. We conducted a study to explore the role of the SMH in explaining individual differences in decision making in normal population, with the aim of solving the puzzle posed by the results obtained by Schutter et al. (2004). These authors found that a brain asymmetry favoring reactivity to punishments (right-sided asymmetry), leads to a more disadvantageous strategy in the standard version of the Iowa Gambling Task (IGT). Materials and methods: Ninety-eight female participants completed eighty trials on both the standard IGT and a reverse IGT which emphasizes the trade-off between immediate losses and larger delayed gains. Asymmetry was assessed with scores on the BIS/BAS scales (Carver & White, 1994). Skin conductance responses (SCR) were recorded from electrodes placed on the thenar and hypothenar eminences of the non-preferred hand. To eliminate unwanted sources of variability between individuals, we standardized SCR data within individuals in our statistical analyses, and focused on finding evidence of scope insensitivity (see Desmeules et al., 2008). Results: Contrary to suggestions in extant literature, performance impairments for the right-sided asymmetry group are not related to generally impaired somatic responsiveness, since this group is found to exhibit unimpaired performance on the reverse IGT. We find evidence of scope insensitivity in skin conductance responses, and focus on the consequences of not differentiating between levels of rewards or punishments within the two tasks. In line with the SMH, we find that anticipatory SCRs bias the decision making of our participants. Solving the puzzle posed by the “reversed” findings of Schutter et al. (2004), we find that those participants with right-sided asymmetry exhibit an anticipatory bias against advantageous options on the standard IGT. Conclusion: Our research emphasizes the importance of first obtaining an appraisal response to large losses in the standard IGT, in order for a safe-guarding anticipatory somatic marker to develop, and steer people away from disadvantageous options. The SMH remains the best explanation for individual differences in performance for normal participants, especially those with asymmetrical motivational systems. This research calls for an increased integration of behavioral decision research and neuroscience for a more complete understanding of human decision making. |
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