【作者】 杨旸；

【导师】 陈华富；

【作者基本信息】 电子科技大学 ， 应用心理学， 2013， 硕士

【摘要】 比率偏见效应指的是人们在对两个相同的比率进行比较时，通常会觉得数值较大的比率具有更大的可能性，如在比较1/10和10/100时认为10/100的可能性更大。以往大量研究认为，比率偏见效应的产生与人类决策中的双系统加工机制有关。双系统加工理论人为，人脑中存在分析-理性系统和直觉-经验系统两个加工系统，同时支配人的决策行为，当直觉-经验系统在双系统竞争中占优势时，人就会产生偏差决策，如比率偏见。这一解释被多项行为研究所证实，但还没神经方面的支持。本文利用功能磁共振成像（functional magnetic resonance imaging，fMRI）方法对比率偏见效应进行研究：通过研究不同的被试在完成双系统冲突和非冲突两种任务时的大脑活动差异，深入分析了比率偏见效应中双系统的竞争机制；并利用心理生理交互作用（psychophysiological interaction，PPI）分析方法对比率偏见效应中双系统的脑功能连接性进行了进一步地研究。主要工作如下：1、通过功能定位，研究比率偏见效应中双系统竞争机制。利用基于fMRI的决策实验，我们发现比率偏见程度相对较强的被试在完成双系统竞争任务时，分析-理性系统（右侧背外侧前额叶）和直觉-经验系统（右侧脑岛）的活动均较强，可见双系统的活动对比率偏见效应产生有很大的影响。此外，在被试完成双系统竞争和非竞争任务时扣带前回的活动存在著差异，暗示了扣带前回在双系统竞争中的调节作用。2、功能连接结果显示右侧脑岛与右侧背外侧前额叶在比率偏见任务中存在正的交互作用，并且这一交互作用与被试的比率偏见程度呈正相关。这一结果与之前的功能定位结果一致。此外，以扣带前回为种子区域的心理生理交互分析发现该区域与前额之间存在着与竞争有关的交互作用，提示了扣带前回与前额之前的功能连接在双系统竞争监控中起到的关键作用。通过功能连接分析，我们进一步明确了双系统之间的相互作用，以及它们的竞争监控机制。更多还原

【Abstract】 The "ratio-bias effect" refers to that same probability is experienced as larger if itcomes as a ratio of two larger numbers (eg.1/10and10/100). Previous studiescontributed this phenomenon to the existence of analytical-rational andintuitive-experiential processing systems within models of human choice that is thedual-process theory, but its neural basis is still unclear. Using functional magneticresonance imaging (fMRI) based task we found the subjects with stronger ratio-biaseffect showed more activated in brain areas related both intuitive(the right insula),analytical processing (the right dsolateral prefrontal cortex (rDLPFC)), suggesting thekey role of the two different system in ratio-bias. Moreover, the varied activity of MCCboth across subjects and task demonstrated the conflict between two systems fromneural perspective.This paper mainly focused on the study of dual-system process in ratio bias effectbased on functional magnetic resonance imaging (fMRI). Using functional magneticresonance imaging (fMRI) based task, we analyzed the brain activation of subjects withstrong and low ratio-bias effect, when performing conflict and non-conflict task. Inaddition, Psychophysiological interaction (PPI) was applied to explore the functionalconnectivity of dual-system in ratio-bias effect. Some aspects of this dissertation havebeen put forward:1. Study of the brain activation. The subjects with stronger ratio-bias effect showedmore activated in brain areas related both intuitive (the right insula), analyticalprocessing (the right dsolateral prefrontal cortex (rDLPFC)), suggesting the key role ofthe two different system in ratio-bias. Moreover, the varied activity of MCC both acrosssubjects and task demonstrated the conflict between two systems from neuralperspective.2. Study of the connectivity of brain. The right insula and the rDLPFC were foundpositively interacted during the ratio-bias task, which was consist with the brainactivation results. Besides, PPI analysis with the ACC as the seed area showedconnectivity between the ACC and the frontal and this connectivity was related to competition. This result might reveal that the functional connectivity between the ACCand the frontal played a key role in dual-system competition. Thus, the interaction andcompetition mechanism of the two systems were further demonstrated by functionalconnectivity analysis.更多还原