認同與信任行為的機制：從信任賽局和神經科學的觀點來探討

科技部補助專題研究計畫成果報告

期末報告

認同與信任行為的機制：從信任賽局和神經科學的觀點來

探討(第 2 年)

計 畫 類 別 ： 個別型計畫 計 畫 編 號 ： MOST 102-2420-H-004-009-MY2 執 行 期 間 ： 103 年 01 月 01 日至 104 年 03 月 31 日 執 行 單 位 ： 國立政治大學社會學系 計 畫 主 持 人 ： 熊瑞梅 共 同 主 持 人 ： 顏乃欣、陳樹衡、吳建德、劉鶴齡 計畫參與人員： 碩士班研究生-兼任助理人員：黃瀞儀 博士班研究生-兼任助理人員：楊天盾 博士後研究：范揚騰 處 理 方 式 ： 1.公開資訊：本計畫涉及專利或其他智慧財產權，2 年後可公開查詢 2.「本研究」是否已有嚴重損及公共利益之發現：否 3.「本報告」是否建議提供政府單位施政參考：否

中 華 民 國 104 年 06 月 01 日

中 文 摘 要 ： 第二年計畫招募了五十八位曾參與 2012 年臺灣總統大選的學 生，進行六回合的信任決策任務，佐以功能性磁振造影的掃 瞄。每位受試者均被告知參與信任決策的對手有包含相同、 不同政治認同傾向的玩家（支持馬英九以及支持蔡英文）以 及電腦。行為結果顯示：相較於不同政治認同傾向的對手， 受試者會選擇對相同政治認同的對手提供較高比例的信任決 策行為選擇。功能性磁振造影的結果發現：當相同政治認同 的對手選擇背叛的回饋時，與情緒處理、辨識他人心智狀 態、以及自我調控相關的腦區有顯著的活化，這些區域包含 前腦島、顳頂葉交界區和背外側前額葉皮質區等；同時此些 神經生理效應，會特別發生在對蔡英文有高度政治內團體認 同的受試者。另外，當面對不同政治認同的對手選擇信任的 回饋時，與獎賞學習有關的尾狀核/紋狀體，則有明顯的神經 活動。當受試者對於相同政治認同對手的主觀社會距離感愈 接近時，他們會對於對手的背叛回饋有更顯著地前腦島腦部 活動，此結果隱含著前腦島，可視為個體與政治認同傾向愈 緊密的群體，在互動過程中獲得負向回報時的神經學標記。 綜合上開研究結果，本計畫不僅支持社會認同對於信任決策 行為的關鍵角色，並提供習得認同（政治認同）對於信任決 策行為的神經學證據以及未來相關社會－經濟－神經科學上 的學研拓展。 中文關鍵詞： 政治認同、社會交換、神經經濟學、功能性磁振造影 英 文 摘 要 ： The second year of this project is to recruit 58

healthy adults who share different political

identities, defined by their presidential votes in 2012 Taiwan presidential election (i.e., Ma Ying-Jiu vs. Tsai Ying-Wen supporters), to participate in a repeated binary trust game experiment while

undergoing fMRI scan. Participants were informed that they would play the game with partners with the same, a different or no political identity. At the

behavioral level, participants showed significantly higher probability of trust decisions when a partner shared the same political identity, suggesting that political identities indeed modulate their

cooperative decisions. At the neural level, we found that identities defined by political preferences have different neurophysiological effects on decision

outcomes. When playing with partners with the same political identity, functional contrasts between trials in which a partner defected participants’ trust and trials in which a partner reciprocated participants’ trust showed significant hemodynamic signal changes in brain regions including anterior insula (emotional processing), temporoparietal junction (mentalizing), and dorsolateral prefrontal cortex (self-regulatory control and/or working memory). Notably, these neurophysiological changes were only noted in those subjects with strong in-group identity with Tsai Ying-Wen. When playing with partners with a different political identity,

participants exhibited greater activation in the striatum (reward learning) in response to trials in which a partner reciprocated as compared with trials in which a partner defected. More interestingly, increased activation in the anterior insula

significantly correlated to closer perceived social distances between participants and their partners. In summary, these findings provide the first evidence on the neural foundations for the modulation effects of political identities upon trust behaviors, and

indicate that studies of decision making should account for the role of social identity in altering behavior and brain response.

英文關鍵詞： identity, political preferences, social exchanges, neuroeconomics, functional MRI

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認 同 與 信 任 行 為 的 機 制 ： 從 信 任 賽 局 和 神 經 科 學 的 觀 點 來 探 討

一、前言

信任行為一直是社會學、經濟學和心理學家共同關懷的基礎科學議題，而信任行為的形成機制也長 久地吸引了社會科學和認知神經科學學者的重視。本研究企圖從台灣經驗中，發展出一個能將認同放入 標準的信任賽局的研究議題，因此，選擇從政治認同的角度切入，探討在不同的政治認同中人們的信任 行為產生甚麼樣的變化，同時結合認知神經科學的解釋，以試圖解開台灣隨民主化發展而產生民眾間政 黨與政治認同兩極化的對立現象。本研究在研究正式開始前，針對政治大學大三大四學生，於 2012 年 2 月蒐集大約 1550 份的總統選舉行為調查，調查時詢問受訪者是否願意參與後續信任賽局和 fMRI 等實驗， 有意願者留下聯絡手機和電話。 本研究第一年信任賽局實驗便是針對這些有留下資料的受試者，選取 2012 年總統選舉時投馬英九 和蔡英文的樣本，最後有 208 位受試者願意參與信任賽局實驗。初步研究分析結果發現，信任行為有三 種不同的形成機制：(1)雙贏機制：透過雙贏使雙方利益極大化的現象，在和相同或不同政治認同的人交 易時都會發生。(2)認同效應：在第三階段中，由於受試者可以自由選定要和相同或不同的對手進行交易， 所以認同的效應在一開始第一回合就產生影響。(3)互惠(mutuality)效應：在三個階段中，皆可以看到明 顯的互惠效應發生，尤其在第二和第三階段。(詳細分析結果請參考期中報告與附錄一) 本研究第二年 fMRI 的掃描，選取在第一年賽局實驗中於第三階段可自由選擇進行賽局的對象時， 選擇與相同政治認同者進行的受試者作為研究對象，以表達對所屬的政治認同有較強烈的偏好。第三階 段投馬英九者選擇與相同政黨進行賽局的有 39 位，投蔡英文者選擇與相同政黨進行賽局的有 34 位，fMRI 的掃描從這 73 位受試者中選擇 60 位進行掃描。以下的實驗流程說明與研究分析將以第二年的實驗為主 (第一年的部分已在期中報告中有詳細記載)，而結果與討論部分將整合第一年賽局實驗的結果進行綜合 性的比較與探討。

二、文獻探討

信任是社會科學各領域的大師都認同是建構社會秩序規範的重要機制。經濟社會學家 Fukuyama(1995)認為一個國家的信任規範和經濟表現是有正向相關；政治學家 Putnam(2000)主張信任規 範的建立，是有助於一個社會民主政府治理效率的發展；而社會學家 Luhmann(1979)則認為信任是社會 各種不同團體連結的潤滑劑，信任使得合作成為可能，也對社會秩序維持有貢獻。Coleman(1988)則進一 步從社會網絡與社會資本的角度，發現社區網絡具有封閉性或收斂性，有助於促成社區信任規範的形成， 在這種封閉的網絡中，人們有義務感必須回饋給提供服務的人，關懷公共財、社區教育及鄰居事物等社 區議題(Coleman,1990)。Cook(2005)更是針對以上這些學者無法釐清的信任規範、社會網絡和交換關係， 進行深入的社會學理論的批判和反省。

2 反觀，在台灣的社會環境中，對於社會的一般信任，以及民眾彼此之間的信任關係與日常生活中的 信任行為，常常和民眾彼此之間的政治認同有關。對於相同政治認同的政黨較信任，對於不同政治認同 的政黨較不信任。在台灣的民主政治發展上，由於兩個主要政黨國民黨與民進黨的極化，使得社會中彼 此的不信任感增加，而兩黨的矛盾與衝突主要來自於台灣族群認同和中國文化族群認同的衝突(吳乃德， 2002)。這樣的衝突不只體現在各樣重大的國家政策與兩岸經貿往來上，同時，各樣攸關民生的社會政策 也可能因為兩黨對立的立場產生為反對而反對的現象產生。為了解上述所觀察到的現象，本研究將從政 治認同的角度切入，試圖了解台灣民眾的政治認同與信任行為之間的關係。 (一)認同與信任 許多社會學家懷疑信任規範或是一般的信任是否可以透過個體之間的互動交往而被建立。Cook (2005)提出一個不同的觀點，從社會交換理論的角度來探討信任形成的機制。個體通常被鑲嵌在異質性 的社會結構中，需要面對許多不同的異質性團體，所以個體如何定義與認同自己屬於哪一個團體就變得 很重要，而認同的關鍵在於個體的信任行為。他認為個體對於社會大眾或陌生人的一般信任，可以視為 一種社會交換的關係以此建構出信任的規範。熊瑞梅（2014）使用 2012 年日本、南韓、台灣及中國大 陸的東亞社會資本調查資料，也發現民眾個人觸及的網絡的異質化程度，對於民眾的一般信任有正面效 應。Yamagish, Cook, and Watabe (1998)假設個體可以建立對陌生人的一般信任，因為人類生來就是利他 的，所以能促進慈善行為與一般的信任行為。因此，個體若有較高程度的一般信任，可能較願意冒險去 先相信別人，反之，個體對陌生人若有較低程度的一般信任，可能較不願意冒險去先相信別人。 認同經常會影響社會交換與信任形成的過程。根據同質性的原理，個體較喜愛和相同團體的成員進 行互動，例如：相同的種族、政治觀點，或是相同的次文化(McPherson et al., 2001)。與相同團體的成員 互動，其優點在於能夠降低環境中的不確定性與資訊的不明確性。然而，認同相同團體的傾向也可能造 成在社會認知的界定過程中過分誇大兩個相異團體之間的差異(Quattrone and Jones, 1980)。因此，當個體 定義自己與他人同屬相同群體時，在互動過程中通常會產生情緒的回饋，並且是透過正向的彼此交換資 源與彼此回饋產生的正向情緒，然而，此情感的回饋也會使得其他外團體的人更難去與內團體的成員建 立正向的一般信任關係(Brewer and Kramer, 1986)。

Tajfel 和 Turner 在 1979 年發展了社會認同理論(Social Identity Theory)。這個理論來自於在一系列有 關「微群體實驗範式」(minimal-group paradigm)的研究，結果發現，雖然受試者與同組成員互不相識而 且從來沒有謀面，也沒有實際的互動，他們還是分配給自己所屬組別成員較多的資源。換句話說，即使 沒有先前的互動關係，只要受試者單純地知覺到分類時，就會分給自己的群體更多的資源和正向的評價。 這種知覺上的分類，會讓我們主觀上知覺到自己與他人共屬，從而產生一種認同感。而由這樣的認同所 引起對於內團體成員給予較多的資源及正面評價的傾向，被稱之為內團體偏向；相反，由認同缺乏而引 起的給外團體成員較少的資源及負面評價的傾向，被稱之為外團體歧視。社會認同理論透過個體藉由其 自身的思考，界定出自身屬於哪個團體，而且與該團體有顯著的情感依附，並期望在參與該團體後可使 自己與該團體成員有良好互動，從中獲得自尊(Self-esteem)的需求(Tajfel and Turner, 1986)。社會認同理

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論可能過分強化對於內外團體的差異性，而忽略用認知的解釋去了解人們之間信任行為的差異。政治認 同不像族群認同或國家認同有固定的界線，政治認同可能隨著政治候選人或政黨的改變而出現變化。

由於，政治認同是容易流動的，所以個體在選擇支持不同的候選人或政黨的過程中相對的就會有更 多在認知上的複雜計算。為了減少在認知上的複雜計算外，個體也常常根據同質性的原則來選擇互動的 對象。同質性原則也是其中一個能解釋為何與他人建立信任關係的一個重要因素(H. Liu, E. Lim, H. Lauw, M. Le, A. Sun, J. Srivastava,and Y. Kim.,2008)。同質性原則主張彼此有相似特質的個體較容易建立信任的 關係。彼此具有同質性特質的個體之信任關係，包含彼此之間的信任程度與彼此之間的相似程度兩部分。 更進一步，我們期待能發現是否彼此所具有的特質愈相似，則彼此信任的程度更高。之前的研究指出人 類在進行決策時通常會考慮其所處的社會脈絡，而與相同的認同團體進行互動就是處在於一個彼此相似 的社會脈絡下做決定。 根據社會認同理論與同質性的原則，本研究假設： H1：和面對不同政治認同對手的情況相比，受試者面對相同政治認同對手時會給予對方更多的信任。 (二)結構觀點的解釋(Structural theory of trust)

Yamagishi(2003; Yamagishi et al. 1998)挑戰文化層面與認知層面的解釋，提出結構層面的角度，從彼 此之間鑲嵌的關係來解釋信任與被信任的差異。Yamagishi 認為兩個社會因彼此之間鑲嵌關係差異造成 的結構差異才是造成美國與日本在信任與被信任差異最優先的解釋機制。在集體主義中，行動者傾向和 網絡鄰近者間有小團體/封閉(clique)並長期的關係，彼此成員間都互相認識。在日本的社會中，鑲嵌的 關係被證實都發生在較低的社會流動與地理區域流動的情況中。鑲嵌的關係允許緊密的監控彼此的行為， 並產生第三者名譽的效應，提升緊密關係中關係義務的執行與值得被信賴的行為。鑲嵌的關係提供未來 繼續交易的機會，透過值得被信任的行為降低風險與欺騙。鑲嵌關係也透過非正式規範的社會控制，提 升更多在小團體中緊密持久的關係。 Yamagishi 認為承諾(commitment)和信任(trust)是二者擇一解決社會與經濟交易中降低不確定性的方 法。承諾是對方持續選擇信任，承諾能極小化交易成本/被騙的成本(transaction cost)，透過持久的關係可 降低被騙的風險。先信任陌生人可極小化機會成本，相信並透過與更多人的互動機會，可找到更值得相 信的人與他進行交易。根據 Yamagishi 的看法，日本人生活在較屬於集體主義的社會中，更在乎交易成 本，透過承諾的契約建立持久性的關係，以致於在社會與經濟交易中不會被欺騙。美國人則生活在較屬 於個人主義的社會中，更在乎機會成本，其原因是兩個文化社會關係互動結構的原理差異，而非文化或 認知層面的差異。 在本研究中，我們假設投蔡英文的人更在乎交易成本。由於，民進黨的興起就是過去在台灣歷史的 發展中，透過社會運動、公民集結、抗議政府等方式，成為一種公民集體力量展現的訴求，迫使政府在 訂定相關政策與法案時要更多聽從社會大眾的聲音。在民進黨的基本訴求中比國民黨有更多集體性與集 體力量的存在。我們假設投蔡英文的支持者應該對這個社會與政府體制有更多的批判，而這群人對於陌 生人的信任比較基於過去對方展現的可信任的承諾行為而定，故我們假定投蔡英文的選民，比較強調互 動承諾的原理；如此，可以降地被騙得交易成本。

4 相對地，本研究假設投馬英九的人更在乎機會成本。由於，投馬英九的人對於陌生人的一般信任比 投蔡英文的人高，同時對於政府與施政政策有更高的信任，因此，假設投馬英九的人更願意用信任的方 式，去接觸更多不同類型的人，以期待遇到更值得信任的人，來降低所要負擔的機會成本。 H2：和投蔡英文的人相比，投馬英九的人願意給予對手更多的信任。 H3：和投蔡英文的人相比，投馬英九的人在面對相同政治認同對手時會給予對方更多的信任。 H4：和投馬英九的選民相比，投蔡英文的人，其對相互性的信任回應效應是比投馬英九的選民來得高。 這意味著承諾產生信任的機制，對蔡英文的選民而言是比較強的。 (三)神經科學的觀點 1. 神經科學與信任行為 神經科學對信任行為研究的貢獻 隨著神經科學在跨領域研究上的巨大影響，神經科學方法用在信 任行為的研究也有新的進展。使用 fMRI 進行信任賽局的實驗時，可以提供信任賽局理性選擇認知機制 所無法測試的腦部情緒面的活動。fMRI 可以提高腦空間訊號及多樣性資訊呈現之優點，也可比較精確 地觀察進行認知作業時活化之腦部區域。具體來說，過去在研究賽局行為時，比較注重社會認知對於行 為決策的影響，忽略決策行為受到認知與情緒的同時影響，而引進神經科學的觀點，則可以將過去賽局 不能釐清的理性認知和情緒反應或兩者之間的因果關係可以進一步的分離，進而修正過去的相關理論。 近年來 Michael Macy(Macy and Sato ,2002; Kuwabara, Willer, Macy, Mashima and Teri and Yamagishi, 2007)在康乃爾大學帶領許多學生投入進行社會關係的建立並結合神經科學的解釋觀點。 過去神經科學對於行為認知和情緒面的研究發現，主要有兩方面。一方面是大腦活動的模式，特別 是人們認知和情緒反應類型不同時，活動的部位和模式是不同的。大腦活動和行為是有相互關連的。第 二方面，大腦活動被假設為和無法觀察到的立即心理過程和行為真相是有關的。這些透過問卷或田野行 為觀察無法觀察的行為，包括人們對許多社會制度安排不公平所產生的負面情緒反應或一個人的身心狀 態會產生的負面情緒反應（例如：說謊、詐騙、歧視、或不信任某些特定的人等等許多在道德規範約制 下不願揭露的認知與情緒反應）；或不同誘因系統的社會效用(social utility)誘發人們的理性行動決策。 同樣的誘因系統，人們處在不同的身心狀態下，心態結構不同，認知與情緒反應也會不同。 過去研究已經發現的大腦活動與精神過程的大腦活動區與關連機制大致如下： (1)腦島（Insula）和 杏仁核（amygdale）是主掌情緒狀態，例如：嫉妒和仇恨。在賽局行為的設計上 可以使用社會效用模型。

(2)右背側前額葉皮質（Right dorsolateral prefrontal cortex）是主掌認知的自我評價能力， 例如：人們 有自私行為反應時，該腦區會活躍。 (3)前額皮層（Orbifrontal contex）主掌人們的認知與情緒決策。當人們看到吸引人美麗的畫面時，或 喜歡的人時，這個腦區的活動會比較活躍。 信任賽局是由兩個人來進行，信任啟動者(trustor)和願意產生信任行為者(trutstee)。當行動者採取信 任對方的選擇行動時，人們腦部掌管嫉妒仇恨的腦島（insula）活動區等呈現負面情緒反應的特徵會減 弱。然而， 若是一次賽局的交易，人們會傾向於自私行為的選擇，而掌管右背側前額葉皮質（Right

5

dorsolateral prefrontal cortex）等掌管自利情緒的腦部活動區會比較活躍。本研究也假設在進行 fMRI 掃描 時，可以同時看到受試者在上述的三個腦區中有較活躍的腦部活動。

2. 神經科學與政治認同

一些政治學家發現政治認同與投票行為和人們的基因遺傳和腦部活動特質是有關的。學者發現 DRD2 基因和政黨傾向與投票行為是有關的(Fowler, Baker and Dawes ,2008; Fowler and Dawes ,2008, fowler and Schreiber ,2008 ;Dawes and Fowler,2009)，有政黨傾向者會有 DRD2 基因的 A2 allele.，這個基 因是顯著地和腦部神經傳導物質（striatum）中的 D2 dopamine receptor density 有關；且這部分腦區專門 司職處罰搭便車者，高政黨傾向者處罰對方時，會產生比較放鬆解壓的快樂感。此外，具有高政黨傾向 者，偏好懲罰個人在公共財上搭便車的心態(Smirnov 2007)。這個研究發現在一個信任賽局中，對政黨有 偏好者比對政黨沒有偏好者更可能信任陌生人。Downs (1957)解釋理性的投票者往往無法充分地獲知候 選人的完全訊息，便進行投票決策行為的選擇；人們使用政黨政治進行政治行動決策，主要目的是透過 組織可以降低訊息成本。政黨認同和吸收政治訊息的成本成反比，一個人有政黨認同，吸收政治選舉的 訊息成本相對較低。跨國比較研究顯示一般認知能力較好者，比較傾向於是有政黨傾向者。學者也發現 DRD2 基因和投票、結盟、少數族 群的代表性，族群關係、國族主義、社團參與等政治行為是有關連 的。

政治認同和投票行為之間的關係與腦神經活動的變化是有關連的。Westen et. al（2006）使用美國 2004 年的總統選舉研究來測試受試者，針對受試者認同的總統候選人和反對的總統候選人，提出不利 於他們支持的候選人政策相關的訊息，企圖刺激受試者對看到總統候選人資訊時，產生不信任的情緒反 應，並觀察受試者的情緒反應和腦神經活動區的變化。這篇研究發現人們經常會為所支持的 政治人物 辯護，這種情緒反應是 motivated reasoning，當人們使用這樣的心理機制時，腦神經的幾個地區是活躍 的，如：ventromedial prefrontal cortex，posterior cingulated，lateral orbitofrontal cortex 等區。

Schreiber D, Fonzo G, Simmons AN, Dawes CT, Flagan T, et al. (2013)的研究中發現，82 位包含支持民 主黨與共和黨的受試者，在考慮風險行為時腦部活動的區域是不相同的。雖然，支持民主黨與共和黨的 受試者在考慮風險時，並沒有顯著在外在行為上的差異，但在 fMRI 的掃描中卻發現，民主黨的支持者 在 left insula 的腦區有更活躍的活動，共和黨的支持者則在 right amygdala 的腦區有更活躍的活動。結果 顯示，民主黨與共和黨的受試者在面對風險的時候有不同的認知過程，這個證據支持了支持民主黨的人 在面對威脅或不確定的事物時，會較敏感而容易產生恐懼的情緒，並以恐懼作為認知過程的判斷。本研 究也假設在投馬英九與投蔡英文的兩群支持者中，對於信任行為也有不同的認知過程與腦部的情緒活動， 透過 fMRI 的掃瞄解開這兩個群體在彼此不信任與對立背後，其運作認知決策過程的差異。 人類處在複雜的社會群體中，必須發展出各種社會化的技巧，來了解、辨識、以及推估他人的動作 及行為意涵。舉例來說，信任行為是交替性社會互動的必要條件之一，我們可經由人與人之間的信任建 立與鏈接，來達到合作以及生存的目的，同時信任與社會認同及經濟決策行為亦有密切的關聯及交互性 的影響。基於上述緣由以及回答相關研究議題所需的跨領域學門合作，本專案計畫最後一年的研究實證， 除持續採用經濟學常用的信任決策任務外，並調控受試者以及對手玩家的政治認同偏好，同時佐以功能 性磁振造影的腦部影像分析，來探討政治認同對於信任決策的行為層面影響以及在神經學上的指標意

6 涵。

三、研究方法

本研究第二年的計畫，從第一年信任賽局實驗中選取受試者志願選擇進行賽局實驗的對象為第二年 實驗的招募對象。我們收錄五十八位先前參與我們行為實驗的受試者，於政治大學的「心智、大腦與學 習研究中心」進行功能性磁振造影的信任賽局實驗。每位受試者依據信任賽局的 trustor 和 trustee 的交換 法則和報酬法則指示，開始進行六回合的信任行為決策，每回包含三十六次的試驗。每回合的賽局會由 電腦隨機決定進行賽局的對手，受試者會遇到三種不同的電腦對手［藍色圓圈遮住人臉（代表 2012 年 投票給馬英九的人）、綠色圓圈遮住人臉（象徵 2012 年投票給蔡英文的人）、以及電腦］。每回合的賽局 一開始您會有 20 點的基本點數，您可以選擇保留（Keep）或信任（Trust），之後對手會選擇「回饋您的 信任」或「背叛」。當您選擇保留時，點數會平均分配，您會得到 10 點，對手也會得到 10 點，所以不 論對手選擇回饋您的信任或背叛您的信任，您都只能獲得 10 點，該回合結束；然而，在顯示結果的畫 面中，你仍然可以看到對手原來的選擇，一種是你選擇保留，對手原本是要回饋您的信任；另一種則是 你選擇保留，但對手已準備要背叛您的信任。當您選擇信任時，則基本點數會自動變成原來的兩倍，也 就是 40 點，這時候，選擇權會移轉到對手，此時有兩種可能發生，一種是對手回饋您的信任，那麼您 會得到 20 點，該回合則結束；另一種是對手背叛您的信任，此時您會得到 0 點，該回合結束。整體而 言，你有一半的對手會回饋你的信任，另有一半的對手會背叛你的信任。我們除了比較不同政黨傾向族 群於信任行為間的差異外，並將分析不同玩家的回饋結果，故此實驗共涵括了以下六種情境: （一）對手為相同政治認同傾向，且提供正向回饋（same/reciprocate, SR） （二）對手為相同政治認同傾向，且提供負向回饋（same/defect, SD） （三）對手為不同政治認同傾向，且提供正向回饋（different/reciprocate, DR） （四）對手為不同政治認同傾向，且提供負向回饋（different/defect, DD） （五）對手為電腦，且提供正向回饋（computer/reciprocate, CR） （六）對手為電腦，且提供負向回饋（computer/defect, CD） 詳細的實驗流程及信任賽局請參見圖一。

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圖一、實驗流程及刺激呈現示意圖

本研究採用 SPM 8 進行 fMRI 的腦部影像資料分析（請參照附錄二）。除了全腦的功能性分析外， 並將針對過去信任賽局的神經影像實驗中幾個重要腦區進行 ROI 分析，包括了尾狀核/紋狀體

（caudate/striatum）、前腦島（anterior insula, AI）、顳頂葉交界區（temporoparietal junction, TPJ）、以及背 外側前額葉皮質區（dorsolateral prefrontal cortex, DLPFC）（請參照附錄二）。最後利用多重迴歸分析方法， 探討此四個感興趣腦區與社會距離間的關係。

四、研究結果

(一)描述性分析 在第二年的 fMRI 實驗中，每位受試者在做完 fMRI 的掃描後，會請他們進行 15-20 分鐘的深入訪談， 包含回答在實驗中整體的感覺、螢幕圖像是否有喚醒政黨意識、被背叛或被信任的感受，以及實驗過程 中其決定信任或不信任的主觀判斷依據為何。依受試者主觀的回憶描述，在進行實驗時受試者的決策策 略可以分為四種： 1.完全依據政治認同：受試者在進行判斷時完全根據對手的政治認同來做判斷； 2.完全依據互惠機制：只要對方回饋我，我就信任他，只要對方背叛我，我就不信任他，在決策時不考 慮對方的政治認同傾向是否與自己相同； 3.混合政治認同與互惠機制：同時使用這兩種機制來做判斷； 4.全部選信任/不信任：216 回合全部選擇信任或不信任。 如表一，為受試者訪談內容的初步整理結果，透過質性資料呈現，並配合行為學資料與 fMRI 的分 析，將幫助我們更準確的明白不同政治認同的受試者在決定信任或不信任時，背後的運作機制為何。 表一、四種不同策略的決策者之訪談摘要 受訪者 政治 認同 太陽花是否影響 政治認同 決策的策略

8 Sub0004 Ma 偏藍→中立 (沒去現場) 前面第一、二 run 用對手來判斷是否 trust，剛開始比較有喚醒政黨意識，但 後來會依據對手的反應來修正自己的行為。後面第三 run 就會開始用金錢來判 斷，沒有特別覺得誰回饋的機率比較高。(3.混合政治認同與互惠機制) Sub0005 Tsai X(有去現場) 理性計算(因記得實驗說明表示回饋機率為 50％，如果對方一開始一直回饋很 低的話，那麼就能猜到接下來他就會給較高，相對的如果對方一直給很高，那 麼就能猜到接下來會背叛。像剛才在實驗時，對方一直給很高，一開始就會壓 抑一直去相信。因為有實驗誘因，有受試費。)( Q：那麼這三者背叛你，哪一 個你會給他的錢更少？A：藍色阿。這樣在場的都知道我的政黨傾向了 Q：所以 在過程中會喚醒你的政黨意識？A：對民進黨就還好，但對國民黨就極度厭惡。) (3.混合政治認同與互惠機制) Sub0013 Tsai X(沒去現場)，對我 來說爛得更爛阿， 而且我希望他快點 倒。 對我來說不是喚醒，我本來就有政黨意識，本來知道藍綠背後代表的意思，所 以我是很確定的做出選擇，不是因為看到顏色才喚醒。因為我就是對另一個顏 色，就是我有很確定的喜好，然後，我覺得那個顏色對我來說，不論他怎樣我 都不會支持他的，因為我認為它後面的那個是很難改的。那如果是綠色的對手 呢?A：我都是選信賴他的阿，雖然他也有背叛我，可是我覺得還是可以給他機 會成長，但我覺得藍色就是完全不需要。Q：所以你信賴或不信賴的時候你會很 根據顏色對手的不同來做選擇？A：對，我是根據它的顏色，因為這個實驗是根 據顏色比較快，但顏色對我來說是有意義的，他是我的政黨認同，還有我對他 後面體系的認識(1.完全依據政治認同) Sub0019 Ma 有影響政治認同， 對國民黨很失望， 因為國民黨是執政 黨，所以標準會更 嚴格。有參加靜 坐。 那這次跟電腦玩阿，藍綠圈是否能喚起你的政黨意識？A：沒有。因為實驗有事 先告知回饋機率，因此受試者計算並希望自己能保有基本的報酬，也就是至少 拿到一半的信任，故全部給信任，這樣一定會至少拿到一半信任所獲得的點數。 因為不論怎麼選擇，對方都有一半的機會給予回饋。在學運發生以前，已經有 改變政黨傾向的想法，因為在野黨提出的政見，較取得受試者的認同。學運則 是增加對藍（馬）的厭惡，更不想投給國民黨。(4.全部選信任/不信任) Sub0008 Ma 偏藍(開始學習注 意其他政黨的意 見，沒去現場) 大概我按幾次 keep 後他會變成開始信任，所以他(電腦)會連續性的背叛幾次， 然後信任幾次，所以就沒看這個背叛的人是誰，最後就以這種計算機率的統計 概念來判斷。我後來發現他(電腦)最多連續出現三次或四次信任，然後就會開 始背叛我。背叛也是頂多三次，就會信任我了。剛開始就是去計算他回饋的次 數。自己比較從數學計算的角度來看。(2.完全依據互惠機制) (二)信任決策的行為結果 我們計算每位受試者於進行信任決策任務時，選擇對對手採取信任決定的比例高低，並比較不同對 手間的差異。結果顯示受試者在面對與自己政治認同傾向相同的對手時，會比不同政治認同傾向對手[t (57) = 2.39, p = .02, d= 0.67]和電腦[t (57) = 2.86, p = .006, d= 0.30]有較高的比例選擇信任的決策。此項發 現支持著政治傾向的差異會調節我們後續的信任決策，特別是面對與自己相同具備相近社會認同的對手， 更會採用合作信任的方案來進行決策任務。 如圖二和圖三，除了考慮與相同或不同政治認同的對手進行賽局外，同時也考慮了受試者本身的政

9 治認同。結果發現，投馬英九的支持者面對相同與不相同政治認同的對手，其信任對方的差異不大，也 沒有顯著的差異性。然而，投蔡英文的支持者面對相同與不相同政治認同的對手，其信任對方的差異就 非常大，達到顯著的差異性。表示投蔡英文的支持者面對相同政治認同的對手就會給予高度的信任，但 面對不同政治認同的對手就給予低度信任，有兩極化的現象，對於本身的政黨或是支持的候選人有較強 烈的政治認同。 圖二、不同政治認同的受試者面對三種對手的信任程度(1=keep, 0=trust) 圖三、不同政治認同的受試者面對相同與不同政治認同對手的信任程度差異 (三)功能性磁振造影結果 1. 對手類型的腦部活動發現： 全腦分析的結果發現，針對不同類型對手的腦部反應存在顯著的主要效果，這些腦區包含了雙側顳 頂葉交界區、雙側尾狀核/紋狀體、雙側中間額葉迴、雙側中顳葉迴、雙側背外側前額葉皮質區、雙側下 額葉迴、雙側中枕葉迴、雙側枕顳葉交界區、右側內前皮質區、右側後扣帶迴皮質、右側前扣帶迴皮質、 右側下顳葉迴、左側前腦島、左側楔前葉、以及左側被殼。事後檢定結果顯示：與對手為電腦時相較， 當面對相同或不同政治傾向的對手會有較多與社會訊息處理及辨識他人心智狀態等相關的腦區有較高 的腦部活動反應，此結果提供了本實驗的實驗操弄（對手為人 vs. 對手為電腦），可真實反映出具有社

10 會性互動線索的證據。另外，與情緒處理（例如右側前扣帶迴皮質及左側前腦島）和獎賞學習（例如左 側尾狀核及左側被殼）有關的腦區，在受試者與相同政治認同傾向的對手進行信任決策任務時，會有較 高的腦部活化；然而，在面對不同政治認同傾向的對手時，相較於相同政治認同傾向的對手則未有較顯 著的腦部反應。 ROI 分析的結果亦顯示左側尾狀核/紋狀體以及左側前腦島對於相同政治認同傾向的對手，在進行信 任任務時有較高的腦部反應；然而在左側背外前額葉皮質區及右側的顳頂葉交界區則未見顯著的腦部活 化（參照表二、圖四和圖五）。 2. 對手回饋的腦部活動發現： 針對對手回饋的全腦分析結果發現：雙側背外前額葉皮質區、雙側中間額葉迴、雙側前腦島、右側 前扣帶迴皮質、左側尾狀核/紋狀體、左側顳頂葉交界區、以及左側顳葉極部有顯著的主要效果。事後檢 定顯示當對手回饋為信任時，左側尾狀核/紋狀體及右側前扣帶迴皮質會有較多的腦部反應；相反地，雙 側背外前額葉皮質區、雙側中間額葉迴、雙側前腦島、左側顳頂葉交界皮質區、以及左側顳葉極部在對 手回饋為背叛時則有較顯著的腦部活動反應。 ROI 分析的結果亦顯示前腦島、背外側前額葉皮質區、以及顳頂葉交界區對於對手回饋為背叛時有 較高的腦部反應；而與獎賞學習有關的尾狀核/紋狀體腦部活化反應，會特別在對手回饋為信任時出現（參 照表三、圖四和圖五）。 3. 對手類型與回饋間交互作用的腦部活動發現： 面對相同政治認同傾向的對手，當對方選擇背叛相較於選擇信任時，會有較為顯著的腦部活動區域 包括：雙側背外前額葉皮質區、雙側顳頂葉交界區、右側中顳葉迴、右側海馬迴、左側顳葉極部、以及 左側前腦島。另外，面對不同政治認同傾向的對手，當對方選擇信任相較於選擇背叛時，雙側的尾狀核 /紋狀體以及右側的海馬迴會有較為顯著的腦部活動反應。 ROI 的分析結果亦證實了此種政治認同傾向所存在的雙重神經學機轉：相近的政治認同會特別調節在執 行信任決策任務時與背叛回饋有關的腦區，這些腦區通常與個體在面對負向結果時的情緒處理（例如前 腦島）以及認知調節（例如背外側前額葉皮質區與顳頂葉交界區）有關；然而，不同政治認同則會特別 調節在執行信任決策任務時與信任回饋有關的腦區，這些腦區反映著個體對於不同社會認同團體的正向 反饋，仍有獎賞與愉悅的腦部神經處理（例如尾狀核/紋狀體）（參照表四、圖二和圖三）。

11 圖四、針對不同對手類型及回饋的腦部活動發現（包含左側背外側前額葉皮質區、右側顳頂葉交界 皮質區、以及左側前腦島的 ROI 分析結果）。 圖五、針對不同對手類型及回饋的腦部活動發現（包含左側尾狀核/紋狀體的 ROI 分析結果）。 4. 受試者政治認同傾向的腦部活動發現： 我們也試著比較受試者的政治認同傾向（支持馬英九 vs.支持蔡英文）在面對與自己相同和不同的對 手時，是否存在與信任決策相關的神經學差異。全腦分析的結果顯示：2012 年支持馬英九的受試者，相 較於支持蔡英文的受試者，在進行信任決策任務時，於左側前腦島、左側背外前額葉皮質區、右側前中 央迴及右側枕顳葉交界處有顯著的神經活動；相反的，支持蔡英文的受試者在右側後中央迴以及左側顳 頂葉交界處則有較高的腦部活動。另外，統計模型亦發現：背外前額葉皮質區及楔前葉具有受試者治認 同傾向與對手政治認同傾向的交互作用效果。事後檢定顯示：投票給蔡英文的受試者在面對相同政治認 同的對手，會有較多與辨識他人心智狀態（楔前葉）及認知調節（背外側前額葉皮質區）有關的腦區活

12 化；然而，投票給馬英九的受試者，不論在面對相同政治認同或不同政治認同傾向的對手時，則未見有 任何顯著的腦部反應。 5. 社會距離與腦部反應間之關係： 實驗結束後，受試者必須填答社會距離問卷(如附錄五)，用以評斷受試者對於相同政治認同對手的 主觀關係緊密程度。我們利用逐步回歸分析，探討受試者在進行信任決策任務時，腦部反應與社會距離 間之關係。結果顯示當受試者對於對手的主觀社會距離感愈接近時，他們會對於對手的背叛回饋有更顯 著地前腦島腦部活動[standardized β = 0.32, t (50) = 2.38, p = .022]，然而其他感興趣的腦區活動，則未見 此種顯著關係[顳頂葉交界區: t (50) = -0.42, p = .68;背外側前額葉皮質區: t (50) = -0.43, p = .67;尾狀核/紋 狀體: t (50) = -0.62, p = .54]。此結果隱含著前腦島對於相近社會認同的背叛或負向回饋，扮演著重要的 神經學標記（如圖四）。 圖四、前腦島腦部活動改變量與社會距離間的關係

四、討論與結論

上述研究成果提供了政治認同的習得認同，對於個體信任決策行為的神經學證據，我們首先發現面 對與自己相近政治認同的對手，會有較高選擇信任的決斷，同時對於對手的背叛或不合作，會產生與處 理負向情緒反應相關的腦區活化，以及顯著的自我調節神經機轉參與，甚者，此些神經效應特別發生在 第一年的信任賽局中，第三場次支持蔡英文的受試者（投資者）且偏好與支持蔡英文（受託人）進行賽 局實驗。然而，面對與自己不同政治認同的對手選擇不合作時，雖然並未顯見與情緒處理有關的神經生 理反應，但面對他們選擇提供正向的回饋，則仍有與獎賞學習有關的尾狀核/紋狀體神經活動。此些行為 與神經學上的結果隱含著個體本身對於不同政治認同的喜好及厭惡程度，影響著接續信任行為的決斷， 並調節著與情緒處理、認知調控、以及獎賞系統等神經機轉。另外，我們可經由前腦島對於與自己相近 政治認同的對手選擇不合作時的腦部活動改變量，來預測個人在與政治認同相關的社會距離緊密程度高 低。未來研究擬將認同等社會因子納入行為決斷的評析，將有助於開展社會－經濟－神經科學等跨領域 學門的學研契機。

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五、未來的研究計畫

過去已有相關的文獻指出，社會認同的歧異，影響著個體信任行為的決策判斷，例如：男性在進行 經濟信任決策任務，相較於女性會採用更高的信任比例，已達到更多機會成本的意義，同時男性在面對 較為信任的對手時（對手選擇正向回饋），會有較高背外側前額葉皮質區的腦部活化；相反的，女性則 有較多內側前額葉皮質區的腦部活動，此項證據支持著男、女性別的歸因認同，調控著我們在執行信任 決策的行為結果與神經生理反應。然而，除了較偏向於天生的歸因認同，社會團體的形成，也依賴很多 後天習得的認同，例如：政黨偏好及國家認同等。迄今，相關實證研究尚缺乏行為和神經學上的依據， 特別是對於信任決策的效應。 因此，為了更加了解社會認同與信任行為之間的關係，下一步計畫除了政治認同外，也開始探討性 別認同與信任行為之間的關係，並透過社會互動學習的各種有關性別的社會規範，如何影響人們日常的 決策行為。 表二、針對不同對手類型的腦部活動發現

MNI Coordinates Zscore Cluster size (mm3)

Brain area x y z

SAME > DIFFERENT

Inferior frontal gyrus 60 20 28 4.03 99

Anterior mid-cingulate 12 -22 28 3.26 12

Precentral gyrus 55 2 26 3.47 99

Inferior frontal gyrus -56 20 26 3.77 15

Thalamus -12 -12 16 3.45 18 Putamen -28 -4 8 3.40 12 Insula -30 28 4 3.46 12 Caudate -2 12 12 4.90 86 Cerebellum -12 -60 -40 4.10 29 DIFFERENT > SAME None SAME > COMPUTER

Middle frontal gyrus 40 18 58 4.55 319

Middle frontal gyrus -40 18 54 4.54 111

Dorsolateral prefrontal cortex -4 62 32 4.73 1251

Precuneus 2 -60 30 5.85 1112

Temporal-parietal junction -54 -66 30 6.36 2981

Temporal-parietal junction 56 -66 28 6.15 4754

Posterior cingulate 2 -50 28 6.22 1112

Dorsolateral prefrontal cortex 56 26 24 4.33 201

Inferior frontal gyrus 46 22 12 3.45 201

Middle occipital gyrus -46 -78 2 6.69 2918

Middle occipital gyrus 50 -74 0 9.22 4754

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表三、針對對手回饋的腦部活動發現

Inferior frontal gyrus -34 18 -16 4.59 168

Middle temporal gyrus 54 0 -24 6.38 4754

DIFFERENT > COMPUTER

Middle frontal gyrus -40 18 56 4.54 115

Dorsolateral prefrontal cortex 20 44 52 4.48 218

Middle frontal gyrus 46 20 48 4.23 151

Dorsolateral prefrontal cortex -2 54 28 3.37 168

Posterior cingulate 2 -50 28 5.97 817

Temporal-parietal junction -46 -62 28 4.94 374

Temporal-parietal junction 58 -64 28 6.25 1642

Middle temporal gyrus 50 -74 0 7.73 1642

Middle occipital gyrus -46 -80 0 5.11 1122

Middle temporal gyrus -62 -14 -8 4.42 691

Medial prefrontal cortex -2 50 -14 4.43 31

Inferior frontal gyrus -28 20 -16 4.21 51

Middle temporal gyrus -50 -10 -20 5.10 691

COMPUTER > SAME

Middle occipital gyrus -36 -88 22 5.86 90

Occipitotemporal region 30 -46 -10 5.67 31

Cerebellum -26 -44 -16 5.38 28

COMPUTER > DIFFERENT

Middle occipital gyrus -34 -88 24 6.12 187

Occipitotemporal region -30 -44 -8 6.57 120

Occipitotemporal region 30 -46 -10 6.78 167

Cerebellum -24 -62 -18 5.14 38

MNI Coordinates Zscore Cluster size (mm3) Brain area x y z RECIPROCATE > DEFECT Caudate -2 18 8 3.96 56 Anterior cingulate 22 36 6 3.25 21

Inferior occipital gyrus 26 -94 -8 4.27 62

Inferior occipital gyrus -22 -92 -12 3.83 119

DEFECT > RECIPROCAT

Dorsolateral prefrontal cortex 6 14 60 4.05 702

Dorsolateral prefrontal cortex -4 16 58 4.36 702

Middle frontal gyrus 36 6 48 3.64 25

Middle frontal gyrus -36 4 48 3.93 127

Temporal-parietal junction -62 -52 28 3.29 17

Insula 42 16 6 3.46 51

Inferior frontal gyrus 56 24 2 3.59 16

Middle temporal gyrus 48 -24 -6 3.81 63

Insula -28 18 -10 3.47 11

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表四、針對不同對手類型及回饋間交互作用的腦部活動發現

MNI Coordinates Zscore Cluster size (mm3)

Brain area x y z

SAME RECIPROCATE > SAME DEFECT None

SAME DEFECT > SAME RECIPROCATE

Dorsolateral prefrontal cortex 2 18 60 3.57 139

Dorsolateral prefrontal cortex -4 8 52 3.29 139

Temporal-parietal junction 56 -44 46 3.23 41

Temporal-parietal junction -52 -50 28 3.40 31

Middle temporal gyrus 46 -42 2 3.86 166

Hippocampus 24 -20 -10 3.49 11

Insula -28 18 -10 3.52 24

Temporal pole -42 14 -16 3.45 26

DIFFERENT RECIPROCATE > DIFFERENT DEFECT

Caudate 0 12 12 4.36 119

Hippocampus 26 -40 10 3.73 21

Caudate -2 20 8 4.24 119

Lingual gyrus 20 -94 -10 3.94 65

DIFFERENT DEFECT > DIFFERENT RECIPROCATE

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附錄一

Mechanisms of Trust Formation under Different Conditions of Political Identity

Yang, Tien-Tun

Ph.D. Candidate, Department of Sociology, National Cheng-Chi University, Taiwan Hsung, Ray-May

Department of Sociology, National Cheng-Chi University, Taiwan Chen, Shu-Heng

Department of Economics, National Cheng-Chi University, Taiwan Du, Ye-Rong

Ph.D. Candidate, Department of Economics, National Cheng-Chi University, Taiwan Lin, Yi-Jr

Postdoctoral Research Fellow, Department of Sociology, National Cheng-Chi University, Taiwan

Abstract

Individual political behavior is a manifestation of social behavior, and individual voting behavior indicates his/her political choices and political identity. After democratization in Taiwan, presidential elections have shown bipartisan polarization and reproduced general distrust of social phenomena. Therefore, this study

intends to explore how people format their trust behavior when they interact with others of the same or different political identity groups through trust game experiments. In stage 1, the computer randomly assigns trustors and trustees without showing political identity of 2012 presidential candidates (Ma Ying-jeou and Tsai Ing-wen). In stage 2, the computer displays political identity logo by random arrangement. In stage 3, the subjects can choose their preferred objects of the same or different political identity logo according to their own preferences. There are two mechanisms of trust behavior formation under different identity condition. （1）Identity

mechanism: Under the condition of political identity choice by subjects, identity effect becomes strongly significant in stage 2 and stage 3 of the experiment, especially for that of Ma-Ma group. （2）Mutuality mechanism: Mutuality effect is very significant in all three stages of trust experiment.

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Introduction

Polarization of presidential election in Taiwan has been a dominant phenomenon in Taiwan. After the lifting of martial law, the media power increased rapidly and individuals’ political views became plural. The media discourses have become polarized through long-term competition of two political parties, Democratic Progress Party (DPP) and Kung Ming Party (KMT). This paper attempts to explore how people format their trust behavior when they interact with others of the same or different political identity groups.

Along with the democratization and globalization, social identity has become important research problem. Individuals not only identify with ethnic groups and nationality, but also identify with all kinds of communities of voluntary groups and subcultures. Political scientists in Taiwan noticed the unique effects of polarized identity on presidential voting behavior; however, they seldom brought trust mechanism into the studies on voting behavior. In fact, citizens in a global society tend to participate in plural voluntary groups and

communities in order to built up their own identity and trust behavior. So it's better to bring trust mechanisms as an alternative perspective to explain voting behavior in Taiwan. We also will further figure out how polarized identity contexts affect the trust mechanism.

This paper will use experimental design of the trust game to export trust forming mechanism. We will use 192 college students who vote for either Ma Ying-jeou or Tsai Ing-wen in 2012 presidential selection. And, this experiment includes three stages. In stage 1, the computer randomly assigns trustors and trustees and does not show political identity of 2012 presidential candidates (Ma Ying-jeou and Tsai Ing-wen). In stage 2, the computer displays political identity logo by random arrangement. In stage 3, the subjects can choose their preferred objects of the same or different political identity logo by themselves.

Literature Review

Trust is the most fundamental mechanisms to build up the social order of a society. The economic development and democratization mainly depend on good foundation of trust norm. Unfortunately, the economic development in Taiwan has lagged behind Korea since 2000, and political discourse on free trade between Taiwan and China have been polarized for two major political parties, DPP and KMT. In last two decades, the global political and economic order has been rapidly restructured, and the major factor in this restructuring process is the rising of China in terms of economic and political power in the world. During the period of 2012 presidential election, the issues on the national interests of free trade between Taiwan and China were debated critically. The historically political conflicts between China and Taiwan have been the major cause of the polarized voting of presidential election in Taiwan.

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Identity and Trust

Some Sociologists doubt the trust norm or general trust can be internalized by individuals, once the norm is established. Cook (2005) proposed different view on trust from social exchange theories. Individuals are often embedded in a diversified social structure, and how to deal with this diversified group identity and produce trust became important issues. She preferred to conceive trust as a social exchange relation instead of trust norm. Yamagish, Cook, and Watabe (1998) assumed individuals can build up general trust toward strangers, because human nature is born with altruism which facilitates charity and general trust behavior. Therefore, those individuals with higher degree of general trust would rather take risk trusting strangers first. In contrast, some people don’t usually trust strangers unless they really gain enough reward through exchange in the process of interactions.

Identity always influences social exchanges and trust mechanisms. Individuals prefer to interact with the same groups of people, including ethnicity, political interest and subculture groups (McPherson et al., 2001). Interactions with homogeneous group members are advantageous for reducing the environmental uncertainty and information asymmetry. However, identity propensity in the social interaction has its disadvantage through social cognitive mechanisms of exaggerating the difference between different groups (Quattrone and Jones, 1980). Therefore, identification with the same groups in the interaction process often produces emotional responses, and these emotional responses will make internal group members positively exchange resources and reward one another; however, these emotions will discriminate those outside groups members and will be hard to establish positive evaluation and general trust to other groups(Brewer and Kramer, 1986).

Tajfel and Turner developed Social Identity Theory in 1979. The theory was developed originally in order to understand the findings of a series of studies designed to examine the minimal conditions that are necessary and sufficient to produce negativity towards out-groups. Tajfel et al (1971) attempted to identify

the minimal conditions that would lead members of one group to discriminate in favor of the in-group to which they belonged and against another out-group. Hence, we tend to overlook in-group differences while

exaggerating out-group differences (Quartrone and Jones, 1980). Social identity theory posits a need to affirm self-esteem by attributing positive qualities to the members of the group with which one identifies (Brewer and Miller 1996; Stets and Burke 2000). In sum, Social identity theory overemphasizes the discrimination

sentiments toward other groups and ignores a cognitive explanation for differences in trust and trustworthiness between people

This paper will focus on the trust game recruiting objects with similar and different political identity in 2012 presidential election in Taiwan. Ma Ying-jiu and Tsai Ying-wen were two major candidates who were supported by two largest political parties in Taiwan. We assume political identity will affect the trust behavior in the trust game experiment. Political identity is different from racial and national identity. Racial and national identity has more fixed group boundary; however, political identity often changes along with the performance of candidates and parties.

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We derive the following hypotheses:

Hypothesis 1a: Trustiness of participants in stage 2 are different from stage 1. Hypothesis 1b: Trustiness of participants in stage 3 are different from stage 1. Hypothesis 1c: Trustworthiness of participants in stage 2 are different from stage 1. Hypothesis 1d: Trustworthiness of participants in stage 3 are different from stage 1.

Political identity and Trust Game

Political identity in Taiwan has changed from the issue of ethnicity identity to the issues of China/Taiwan relations (Gold 1987, Liu 2009). Identity formation has been constructed and developed into two competing identification systems: “treating China as a guest (a different country) or treating China as a host (we are free Chinese in Taiwan) (Liu 2009)”. The conflicting identity between China and Taiwan has been changing along with more economic and political contacts between two societies. The international position of global economy and Taiwan businessmen's interests in China became important mechanism to influence on the logics of identity formation. The fluidity of national identity after 2008 seemed to increase (Liu 2009).

Liu’s (2009) findings on the fluidity of national identity provoke us to propose an alternative simulated experimental design on trust game by bringing the identity contexts of polarized voting groups. In this paper, we attempt to propose a proposal on simulated experiments. Polarized voting groups, voting for Ma Ying Jiu and voting for Tsai Ying-wen, are treated as identity contexts. Liu's (2009) findings implied the fluidity of national identity has occurred recently and could be changed in the political forum and debating process. In order to clarify these issues, bringing identity groups into the design of trust game experiments becomes necessary. Trust game experiments are advantageous to differentiate how trustors and trustees initiate and response the trust in the standard trust game.

Sociologists have engaged in social exchange studies on trust game (Cook, Levi and Hardin 2010， Yamagichi, Cook and Watabe 1998, Raub, Busken, van Assen 2011). They mainly used social exchange theory to study the trust mechanism by bringing trust game into traditional social exchange experiments. Social exchange theorists conceived trust as the formation process of social relations between trustor and trustee. Therefore, the perception of trustworthy manner of two players will influence the willingness to continue the exchange relations and expect to gain reward through initiating the trust first. In trust game, the future degree of expected reward determines the degree of trust action. In a plural and heterogeneous society, the mechanisms of trust relation formation tend to be more like the trust game. Johnson and Mislin(2008) analyzed the findings of trust game experiments from meta analyses. Among 84 experiments, trustors were willing to initiate the trust to trustees in 50.8% of these experiments, and trustors also gained return in 36.5％ of these experiments。

Identity contexts often played important role affecting the variation of trust relation in the trust game (Tajfel, 1970). Sociologists (Kuwabara, Willer, Macy, Mashima, Terai, and Yamagishi 2007) overcome the difficulties of doing cross-culture trust game experiments. They used Japanese and American college students to do trust game experiments on the web simultaneously. These experiments brought the flags (or identity symbols) in standardized trust games. They found that the Japanese trustors tend to build up durable and persistent trust

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relations than American trustors, so group identity seemed to affect the trust behavior more for Japanese. There has been no research on this issue in Taiwan, so, this paper will apply the experimental design of identity and trust game into the simulated research proposal on how political identity affect the trust relation formation in Taiwan.

Because political identity is fluid, actors have more cognitive complexity to perceive political candidates or parties. In order to reduce the cognitive complexity, subjects often classify interacted objects into self and others through the principle of homophily. Homophily is also one of the most important theories that attempt to explain why people establish trust relations with each other (H. Liu, E. Lim, H. Lauw, M. Le, A. Sun, J.

Srivastava,and Y. Kim.,2008). The homophily effect suggests that similar users are more likely to establish trust relations. Homophily in trust relations includes two mechanisms: degree of trust between self and others and similarity between self and others. In more detail, we would like to know whether objects with higher similarity more likely to establish trust relations than those with lower similarity. Previous researches indicate that human decisions are often subject to influence others under social contexts. Identical group is one of these social contexts. Homophily implies that distance in terms of social characteristics translates into network distance, the number of relationships through which a piece of information must travel to connect two individuals

(McPherson, Smith-Lovin, and Cook ,2001).

According to homophily principle, we derive the following hypotheses:

Hypothesis 2a: Participants trust members of a salient similar political identity more than members of dissimilar.

Hypothesis 2b: Compared to voting for Tsai Ing-wen, people voting for Ma Ying-jeou more trust members of a salient similar political identity than members of dissimilar.

Hypothesis 2c: Participants are trustworthy by members of a salient similar political identity more than members of dissimilar.

Hypothesis 2d: Compared to voting for Tsai Ing-wen, people voting for Ma Ying-jeou are more trustworthy by members of a salient similar political identity than members of dissimilar.

Structural theory of trust

Yamagishi (2003; Yamagishi et al. 1998) challenged both the cultural and cognitive explanations, and point to structural differences in the two societies as the primary mechanism underlying the differences in trust and trustworthiness in the United States and Japan, noting in particular that collectivist societies are

characterized by more densely embedded relations.

Yamagishi contends that commitment and trust are alternative solutions to the problem of uncertainty in social and economic exchanges. While commitment minimizes transaction costs associated with misplaced trust, trust minimizes the opportunity costs of commitment. The opportunity cost of commitment is foregoing a

potentially lucrative transaction outside of parochial exchange relations with familiar partners. The willingness to trust strangers minimizes this opportunity cost. However, trusting relative strangers increases the transaction cost of possible exploitation. Commitment reduces this transaction cost by limiting transactions to durable

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relations in which the risk of being cheated is relatively low. According to Yamagishi, Americans tend to focus on opportunity costs and Japanese on transaction costs. The reason is structural, not cultural or cognitive.

In our study, we assume people voting for Ma Ying-jeou focus opportunity cost but increase the

transaction cost of possible exploitation. In contrast, people voting for Tsai Ing-wen focus transaction cost but increase the opportunity cost of possible exploitation.

According to structural theory of trust, we derive the following hypotheses:

Hypothesis 3a: People voting for Ma Ying-jeou are more trusting than Tsai Ing-wen. Hypothesis 3b: People voting for Ma Ying-jeou are more trustworthy than Tsai Ing-wen.

Yamagishi's comparative research is that cross-cultural differences reflect the proximate effects of

differences in relational commitment and investment that shape cognition and behavior (Yamagishi 2003: 355; Yamagishi et al. 1998). Yamagishi's approach is to explain them in terms of relational and institutional

structures that characterize different societies.

These relationships of relational and institutional structures generally constrain individual-agent actions, since relationships imply that at least one contract (or mutual agreement) between the agents must exist. The mechanism that facilitates this “act of faith” is generally regarded as “trust.” In essence, each agent (whether a person or organization) in a relationship mutually trusts that the loss of some control will result in cooperative gains that neither agent could achieve alone (Dariusz G. Mikulski, 2013). With regards to payoff value of trust between agents, this assumption can be interpreted as a universal means for agents to mutually share the value of their trustworthy relationships. Trust cultivation often requires reciprocity between two agents as a necessary behavior to develop trust, and a transferable utility is a convenient way to model the exchange for this notion (Dariusz G. Mikulski, 2013). In this paper, we measured mutuality as the probability of trustworthy between two partners.

According to relationship mutual trusts, we derive the following hypotheses:

Hypothesis 4: People getting higher mutuality are more trusting than lower mutuality.

Research Methods

Sampling

Our target respondents were those who had the right to vote for the 2012 president in Taiwan. The sampling frame of this study is 244 courses of 37 departments and core programs in 9 colleges which mainly offered undergraduate students of the third (junior) or fourth (senior) grades to take in National Chengchi University (NCCU) in the first semester, 2012. We used stratified random sampling method to choose 63 courses as our sample courses. After obtaining the agreement of the teachers, the interviewers went to the classes to conduct the survey. A total of 1550 respondents in 49 courses filled out the questionnaires in the end.

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From 1550 subjects, we elect subjects voting for Ma Ying-jeou and Tsai Ing-wen, and contact them by phone and e-mail. There are 208 students willing to participate in the trust game experiments. Due to the occurrence of experimental errors, we discarded 16 failure examples. The remaining 192 subjects include 121 subjects voting for Ma Ying-jeou and 71subjects voting for Tsai Ing-wen. We only select data of the first five rounds for the analysis each stage1.

Research Design

In this paper, we use z-Tree which was created by Fischbacher ,Department of Economics, University of Zurich, to perform our trust game experiments. We designed the ‘Trust game’ which is a two- players game in which player A(Trustor) is given 10 points. First, player A(Trustor) has the option to give part of that to player B(Trustee) and keeps the rest for herself. Whatever points player A(Trustor) chooses to give, the game

organizer trebles those points and gives them to player B. So if player A keeps 4 points to herself and gives 6 points to player B, then player B actually gets 18 points. Second, player B has the option of giving any of what he receives back to A. So, for example, if A gives 10 points and keeps nothing for herself and B gives back 25 points to A, then in the end, player A gets 25 points and B gets 5 points.

This experiment includes three stages, and each stage at least run 5 rounds. From the sixth round, the probability of each round proceeding is 50%. Random stopping rule is designed to mitigate the influences of the ending effect. Benchmark return is calculated for each stage of the last five rounds, and three stages add up. One point is equate to two NTD. This experiment includes three stages. In stage 1, the computer randomly assigns trustors and trustees and does not show subjects’ political identity to 2012 presidential candidates (Ma Ying-jeou or Tsai Ing-wen). In stage 2, the computer re-assigns trustors and trustees randomly but displays their political identity logo. In stage 3, the subjects can choose their preferred objects of the same or different

political identity logo by themselves. Each stage represents different experimental conditions

We assume people in each round of three different stages of experiments have different degree of trustfulness and trustworthiness. We also assume the political identity logo will influence the degree of trustfulness and trustworthiness.

Results

Descriptive Analysis

Table 1 shows the behavior of trustfulness and trustworthiness for all participants in fifteen rounds of three

1

From the sixth round, the probability of each round proceeding is 50%. Random stopping rule is designed to mitigate the influences of the ending effect.

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stages. Social psychologists think voting is a group behavior, and voters’ choices are affected by social groups surrounding them.

Table 1. Summary Results by Experimental Condition and Participant Political Identity Condition

condition Stage 1 Stage 2 Stage 3

Participant political identity Ma Tsai Ma Tsai Ma Tsai

Mean(SD) Mean(SD) Mean(SD) Mean(SD) Mean(SD) Mean(SD)

Total Profit(point) 74.22(20.060) 75.62(28.695) 90.84(22.162) 87.06(23.670) 86.93(22.129) 79.22(20.626)

Final Profit(point) 64.98(14.182) 64.70(20.601) 66.16(12.012) 64.85(14.186) 69.53(7.882) 66.62(12.784)

Average entrustment to trustee(Ma) , per round

7.79(2.800) 6.14(3.473) 8.56(2.435) 7.11(3.528) 8.84(2.361) 7.88(3.059)

Average entrustment to trustee(Tsai) , per round

6.64(3.180) 6.89(3.471) 7.92(3.020) 7.03(3.419) 8.24(2.091) 7.59(3.372)

Average return entrustment to trustor(Ma) , per round

11.02(6.215) 8.89(5.743) 12.70(4.701) 11.05(5.819) 12.98(4.143) 11.89(3.472)

Average return entrustment to trustor(Tsai) , per round

8.22(6.301) 10.75(7.641) 10.26(6.040) 10.22(6.477) 11.65(5.326) 10.68(5.948)

Statistical Models

Table 2 reports the regression coefficients explaining the transaction amount which trustor entrusts trustee in each transaction through the random-effects regression models. We used subject’s political identity,

homophily of political identity between trustor and trustee, and stage of experiment to test all the hypotheses mentioned before. Political identity was coded 1 voting for Ma and 0 voting for Tsai in 2012 Taiwan

presidential election. Homophily was coded 1 if the transaction partners were both voting the same president candidate and 0 otherwise. Three stages of experiments were coded 1, 2, 3 respectively.

Model 4 does not show the significant effect of different stages on trustfulness (Hypothesis 1a and 1b). Trustiness of participants are no significant difference between stage 2 and stage 1. Trustiness of participants are also no significant difference between stage 3 and stage 1. However, in Model 5, if we do not control the variable that people in the first round give all ten points to their partner, stage is significant. Trustiness of participants are significant difference between stage 2 and stage 1 ,and between stage 3 and stage 1. Especially, in stage 3, trustiness of participants are more significant. Because participants can choose their preferred objects of the same or different political identity logo by themselves in stage 3, we can find stronger identity effect. Through the cross tabulation(stage * frist_10_points ), there are 32.5％ people who in the first round give all ten points to their partner in stage 1. But, there are 52.1％ in stage 2 and 62.5％ in stage 3. There are most of the proportion of people who in the first round give all ten points to their partner in stage 3. Therefore, when we control the variable people who in the first round give all ten points to their partner, we can not see the

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Model 2 does not show the significant effect of homophily principle on trustfulness (Hypothesis 2a). The major reason is that the average entrustment of political identity group for Tsai-Tsai (Tsai-Tsai is that both trustor and trustee vote for Tsai Ying-wen) is much lower than that of political identity group for Ma-Ma in stage 2 to stage 3 of Table 1. Evidently, homophily effect varies by Ma-Ma and Tsai-Tsai groups. After the homophily variable is classified into four combinations of political identity in Model 3, the significantly strong effect of Ma-Ma than those of other groups. In Model 3 (Hypothesis 2b), Tsai-Tsai and Tsai-Ma are significant less than Ma-Ma. It means homophily hypothesis only happens in people voting for Ma but not happens in people voting for Tsai. Participants voting for Ma trust members of a salient similar political identity more than members of dissimilar.

The results strongly support Hypothesis 3a. In Model 1 & Model 2, subject’s political identity is significant. It means people voting for Ma Ying-jeou are more trustful than those voting for Tsai Ing-wen. According to structural theory of trust transaction, people voting for Ma Ying-jeou emphasize opportunity cost in each transaction. The opportunity cost of trust transaction is foregoing a potentially lucrative transaction outside of parochial exchange relations with familiar partners. The willingness to trust strangers minimizes this opportunity cost. Therefore, it means people voting for Ma Ying-jeou are more willing to trust strangers for missing better exchange opportunities.

In contrast, people voting for Tsai Ing-wen emphasize transaction cost of possible exploitation. Commitment are alternative solutions to the problem of uncertainty in social and economic exchanges. Commitment reduces this transaction cost by limiting transactions to durable relations in which the risk of being cheated is relatively low from previous literature. Therefore, it means people voting Tsai Ing-wen are not easy to trust strangers because of the risk of being cheated is high when they play with their partners in

temporary relationship. In Model 7, we add interaction effects of political identity and mutuality. A negative coefficient for this interaction effect indicates that the mutuality effect on trustfulness is stronger for people voting for Tsai than people voting for Ma. People voting for Tsai seem to pay the trustfulness according to commitment principle. Even though they are more difficult to trust others in the beginning, they tend to return more once they gain more from others.

In Model 6, the results provide support for Hypothesis 4. The effects of mutuality on trustfulness are significant. It means people with higher mutuality are more likely to be trustful than those with lower mutuality. Therefore, mutual agreement between the participants must exist, and mutual agreement can facilitate this “act of faith” is generally regarded as “trust.”