| Summary: | 碩士 === 東吳大學 === 心理學系 === 95 === Gehring and Willoughby (2002a) determined that a newly discovered event-related potential, medial frontal negativity (MFN), can not be represented only by gain-loss evaluation, and is correlated with the level of risk associated with choice in a subsequent trial. Large loss induced a large MFN, which is linked to a risky choice in next trial and vice versa. The study of MFN engenders considerable argument in the behavioral and physiological fields, such as those obtained by Nieuwenhuis, Yeung, Holroyd, Schurger and Cohen (2004), who utilized the same task and determined that MFN is not different from Error-Related Negativity (ERN). This investigation manipulates a critical variable, monetary value, to identify the discrepancies between MFN and ERN.
Most study procedures followed those in the experiment by Gehring and Willoughby. The first experiment manipulated two variables, gain-loss and monetary value; the second experiment manipulated two variables, right-wrong and monetary value. We hypothesize that if MFN exists and the variant monetary value modifies MFN magnitudes in these tests, otherwise, ERN will be predictable in these experiments. The results of first experiment indicated that manipulating monetary value did modulate subject choice on behavior level; however, MFNs in response to variant values were not significant. In the second experiment, the effect of manipulating monetary value was not observed; subject choice behavior was primarily dominated by right-wrong feedback. Furthermore, ERNs regarding to variant conditions were also non-significant.
In conclusion, the manipulation of monetary value can be identified on behavioral level in the gain-loss experiment, but not in right-wrong experiment. Conversely, the effects of MFN or ERN cannot be verified using these two tests. The insignificant physiological results may be caused by the long test procedure that exhausted subjects and produced excessive eye-movement and internal noise. Consequently, in future studies, Near-Infrared Ray (NIR) may prove useful solving the controversy between MFN and ERN. Furthermore, functional Magnetic Resonance Imaging (fMRI) study, which possesses relatively high spatial-resolution, may be applicable to identifying the source localization of MFN and ERN.
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