Damasio(1994)提出軀體標記假說（Somatic Marker Hypothesis）來解釋情緒如何影響行為決策，認為人們在決策前，與過去的情緒經驗關聯的生理反應會再現，幫助人們做出較好的決策判斷。並利用愛荷華賭博作業（Iowa Gambling Task）來模擬日常生活決策情境，並同時紀錄膚電反應(Skin conductance respons)，量測受試者決策前的預期膚電反應（Anticipatory SCR）和結果呈現後的回饋膚電反應(Feedback SCR)，加以佐證其神經生理機制。本研究將從三個方向進一步驗證其假說，分別是風險因素、生理證據和個別差異。在愛荷華賭博作業中，期望值負的牌也是高風險程度的牌，使結果無法清楚解釋是期望值或者風險程度造成的影響。而過去雖然有許多研究也使用膚電反應當做生理指標，但有許多相異的研究結果，並且較少研究利用事件關聯電位瞭解其中樞歷程。再者，過去相關研究發現個別差異的存在，但是缺乏一致的解釋。因此，本研究以修改版愛荷華賭博作業，控制期望值皆為零的狀況下，操弄風險程度，並且利用膚電反應和事件關聯電位當作周邊和和中樞的生理反應指標，探討受試者在單純風險情境，是否也會受到情緒軀體標記影響風險行為偏好，以及各項生理指標和風險行為偏好間的關聯，並瞭解不同風險偏好的受試者生理指標是否有所差異。結果發現，從行為上顯示有風險追逐和風險趨避兩組受試者，不同風險程度的牌損失回饋對受試者的歷程影響也不一樣，額葉的腦部回饋相關負波(Feedback-related Negativity，FRN)結果顯示，風險追逐的受試者對高低風險損失時的FRN沒有差異，風險趨避的受試者看到低風險損失時的FRN大於看到高風險損失時的FRN。此外，看到高風險酬賞比起低風險酬有較大回饋膚電反應的受試者，和看到高風險損失比起低風險損失有較小回饋膚電反應的受試者，接受高風險牌的比率也較高，其它生理變項對風險行為偏好沒有顯著的預測力。並且預期膚電反應並非過去研究認為單純扮演警訊或者誘因，而有更複雜的機制存在，受試者在接受非偏好的牌和拒絕偏好的牌前有較大的預期膚電反應。預期階段N170的結果顯示，受試者看到刺激之後會拒絕的N170會大於之後會接受的N170，顯示接受或拒絕兩種不同情境時受試者對刺激的處理歷程亦相異。 / Somatic Marker Hypothesis was proposed to explain the influence of emotion on decision making. To examine this hypothesis, Damasio and his colleagues designed the Iowa Gambling Task (IGT) and found that the “anticipatory skin conductance responses (SCR)”, i.e. somatic markers, was elevated before selecting from bad decks to serve as alarms and it warned participants not to select “bad deck” which was negative expected value. However, there are three unsolved problem in these IGT researches: the risk factor, inconsistent physiological evidences, and individual differences. In the original IGT, the bad decks are also more risky and that confounds the interpretations of participants’ choice behaviors and related physiological evidences. There are inconsistent evidences of how the anticipatory SCR and feedback SCR related with choice behaviors. Moreover, there are little event-related potential IGT studies. To solve these issues, the primary aim of the present study is to clarify whether decision making is influenced by risk level even when all options have the same expected value. A modified IGT with high risk deck and low risk deck was used and the expected values of two decks were all zero. Moreover, the procedure was different from original IGT. Participants saw a deck with mark first and then decided to accept or reject this deck. Thus, the role of anticipatory SCR could be clarified more clearly. In addition to SCR, ERP was also recorded for further physiological evidences. To elaborately clarify individual differences of choice behavior and physiological evidences, participants would group to risk-seeking (i.e., accepting more high risk deck and rejecting more low risk deck) and risk-aversion (i.e., accepting more low risk deck and rejecting more high risk deck) according their choice behaviors. The result revealed that the participant who accepted more high risk deck, their reward SCR was higher from high risk deck than from low risk decks, and induced lower punishment SCR from high risk deck than from low risk decks. Moreover, the anticipatory SCR was higher both before they decided to reject the liked deck and before they decided to accept the disliked deck. The results of feedback-related negativity (FRN) from ERP data in frontal region showed that the magnitude of FRN was larger under the conflict punishment (the punishment from low risk decks) condition for risk-aversion participants. The results of N170 from ERP data showed that the magnitude of N170 was larger under the reject condition. These results suggest that the SMH could be explained not only with expected value but also with risk preference. In conclusion, the interpretation of anticipatory SCR by previous study was not completed, and it reflected not merely the negative feeling or positive feeling. This strong anticipatory emotion affects people to change the routine behavior about their risk preference, and there exist individual differences of choice behavior and physiological evidences.