【作者】 王翠翠；

【导师】 马庆国；

【作者基本信息】 浙江大学 ， 管理科学与工程， 2014， 博士

【摘要】 在与他人(群体)态度、看法或者行为相关的信息基础上,做出一致或者不一致性的决策行为,被称之为信息性从众决策或反从众决策,它是从众行为的一个基础表现形式。研究信息性从众行为的认知机制,对于从众行为研究具有重要的基础理论意义。另一方面,传统决策研究往往只关注与财产(数字表征)相关的情景,而现实生活中的很多决策并不与财产相关的,而是涉及生命、健康等主题(非数字表征)。将财产类决策和健康类决策进行对比,它们的决策情景不同,在从众信息的影响下,其表现也可能不同。通过这种对比,将有助于进一步解释信息性从众行为背后的深层次机制。基于此,本文重点对财产类和健康类两种情景下信息性从众决策进行对比研究。回顾已有研究,围绕从众行为理论中有关信息性从众的研究进展,本文重点关注以下三个问题：(1)信息性从众决策是否存在一种稳定的认知机制?(2)如果存在一种稳定机制,其在财产类决策和健康类决策中,是如何表现出差异性的?(3)通过这种机制,对于财产类和健康类信息性从众决策,是否有优化决策的管理建议?我们选择股票购买决策作为财产类决策的代表,食品购买决策作为健康类决策的代表,在研究中考虑到性别、投资经验等因素,从行为科学层面和神经科学层面,通过四项研究对上述问题进行回答。研究一通过问卷研究方式,对股票购买情境下基于财产信息的决策和食品购买情境下基于健康信息的从众决策进行研究,主要关注信息信任程度、从众程度、从众速度在两类决策类型下的差异,同时也考虑了性别因素对上述的影响。研究一是从行为学层面进行研究,是后续三个研究的基础。研究二主要从决策神经科学的角度,通过事件相关脑电位(event-related potentials, ERPs)研究方法研究传统的财产相关的决策问题,即,对股票购买决策下,信息性从众和反从众行为的神经机制进行研究。通过把决策过程分为信息感知阶段、决策阶段和反馈阶段三个阶段,分析每个阶段对应的认知加工过程及其在决策中的意义；除此之外,还探讨了性别和投资经验等因素对上述决策过程的影响。研究三和研究四通过ERPs研究方式研究非财产相关的健康决策问题,即,对食品购买决策下,信息性从众和反从众行为的神经机制进行研究。研究三主要针对决策过程的信息感知阶段,考察了人们对含有健康风险信息食品的感知,以及非传统信息性信号(食品口味)对上述信息加工的影响；研究四主要针对决策阶段和反馈阶段,研究信息性从众如何通过决策和反馈被进一步强化的过程。通过整合四个研究,得出了以下研究结论：(1)信息类别(财产类、健康类)和效价(正性、负性)影响信息的信任程度。健康信息的信任程度比财产信息的信任程度高,负性信息比正性信息的信任程度高。(2)基于财产信息和健康信息的决策在从众程度、从众速度上存在差异。正性信息下,两类决策在从众程度、从众速度方面不存在差异；负性信息下,健康类决策从众程度更高,更倾向于马上进行决策。(3)基于财产信息从众行为的神经机理可以由N400、错误相关负波(error related negativity, ERN)、反馈相关负波(feedback related negativity, FRN)、P300成分反映。股票购买决策情景下,信息感知和决策阶段,反从众的决策行为被监测到更大的冲突,由与冲突和自我控制相关的N400和ERN来反映；反馈阶段,从众和反从众行为对结果的评估存在差异,反从众行为更重视反馈结果,对结果情感反应更强烈,从众决策行为可以减缓个体经历强烈的情绪,由与情感和决策相关的FRN和P300来反映。(4)基于健康信息从众行为的神经机理可以由N400、晚期正电位(late positive potential, LPP)、ERN、N400(FRN)成分反映。食品评估决策背景下,对于食品含有健康风险的信息会产生冲突,健康风险的类型不同,情绪反应不同,分别由N400和LPP反映；反从众行为比从众行为在决策阶段监测到更大的冲突,由ERN反映；反馈阶段,反从众行为对于不同反馈感知不同,从众行为则没有显著差异,由N400(FRN)反映。除此之外,食品物理信息(口味)影响健康风险信息的感知,反映在对N400振幅的调节上。(5)性别对信息信任程度的影响表现在：女性比男性更相信健康信息,更不相信财产信息；但性别对信息性从众和反从众没有稳定显著性的影响。(6)投资经验对股票购买决策中的信息性从众行为在行为科学层面有显著的影响,表现在没有经验的个体从众程度更高,更加激进冒险。本文主要基于股票购买决策和食品购买决策对信息性从众行为从行为学层面和神经科学层面进行研究,其创新点主要表现在以下几个方面：(1)弥补了不同决策背景下从众行为对比研究的不足。已有对从众行为的研究主要集中在不同的学科领域的纵向研究,而对学科领域之间的横向研究非常少。本文对财产类决策(股票购买决策)和健康类决策(食品购买决策)中的从众效应进行了对比研究,弥补了上述漏洞,并且建议政府等相关部门关注负性健康信息,因信息信任和传播可能给社会带来恐慌或不稳定性,在资源有限的情况下优先处理这类信息性从众。(2)借助ERPs实验研究方式,从神经科学的角度解释了从众效应存在的原因。前人对从众的原因主要从群体压力、信息不对称性等角度进行分析,对反从众主要从求异需求方面进行解释,然而这些解释都是主观的描述性解释。本文从神经科学的角度对此进行了研究,发现从众效应出现的原因在于个体执行反从众行为会感知到冲突,因此个体必须付出一定的认知资源和注意力去克服冲突才能实现反从众行为,所以一般情况下从众程度远远大于反从众程度。(3)发现从众和反从众行为之后对行为结果的评估上存在差异,并给出了神经科学层面的依据。已有关于从众反从众行为的研究主要从定义、动机和影响因素三个方面进行研究,极少研究从众或者反从众行为之后对结果的评估。本研究借助ERPs实验手段,发现个体在执行从众和反从众行为之后,对反馈结果的主观评估存在差异,从众行为能够减缓个体对负性反馈结果的情感反应,而反从众行为之后则更重视结果,情感反应较强烈。(4)发现食品口味能够调节健康风险信息中N400的振幅,为N400的研究提供了新视角。已有N400的研究主要关注词语之间或者词汇与语境之间的匹配性,主要反映不匹配或者冲突。在本文中,食品和含有健康风险之间因为词汇与语境存在冲突,诱发了N400成分,然而食品的口味因素能够调节N400成分,这对N400的研究是一个新的视角。这是本文的第四个创新点。更多还原

【Abstract】 Based on the information of attitudes, beliefs or behavior of others (groups), individuals make decisions consistent or inconsisitent with the information, which is called informational conformity or counter-conformity. They are basic forms of conformity behavior or conuter-conformity behavior. It is very important for basic theory development to study the cognitive mechanism of informational conformity and counter-conformity. On the other hand, traditional decision researches tend to focus on property-related decision which can be represented by figure characterization. However, in the real word, a lot of decisions are not related with property but related with life, health and so on (non-figure characterization). Comparing with property-related decisions and health-related decisions, the informational conformity would have difference, since the information of conformity is different. From the comparision, it will help to further explain and understand the deep-seated mechanism of informational conformity. Thi thesis focuses on the comparision of informational conformity and counter-conformity with two different scenarios of property-related decisions and health related decisions. In this study, we select the purchase of stocks as a typical case of property-related decisions and food-buying decision as a typical case of health-related decisions.In order to promote the study of conformity behavior, we review the existing researches and propose the following three research questions.(1) Is there a stable cognitive mechanism of informational conformity?(2) If there is a stable cognitive mechanism, are there any differences on informational conformity behavior between property-related decision making and health-related decision making, and how to present these differences?(3) From this mechanism, are there any suggestions to optimize decision making for property-related informational conformity and health-related informational conformity? We select the stock-buying decision and food-buying decision as typical cases of property-related decisions health-related decisions, respectively. In this study, we take gender, investment experience and other factors in to account on the effect of conformity. To answer these questions, we design and complete four studies.Study1uses questionnaire to investigate the decisions based on property-related or health-related information under the background of purchasing stocks or foods. It focuses on the differences of trust level of information, conformity extent and the decision making speed in the two types of decisions. In addition, it takes the gender factor into account. Study1is focused on the behavioral results and is the basis for the subsequent three studies.Study2, from the perspective of decision neuroscience, uses ERPs (event-related potentials) experiment method to study the neural mechanisms of informational conformity and counter-conformity in the purchase of stock decision. We divide the decision-making process into three stages:information perception, decision-making and the outcome evaluation stage. In addition, we consider the influences of gender and investment experience.Study3and study4use ERPs research method to study the neural mechanisms of informational conformity and counter-conformity in the purchase of food decision. Study3focuses on the information perception stage, and investigates the perception of food with health risk information and the effect of food tastes on the perception. Study4focuses on neural mechanisms of informational conformity in the decision-making stage and the outcome evaluation stage.We integrate the four studies and reach six conclusions as follows:(1) Information category (property-related and health-related) and valence (positive and negative) influence trust level of information. The trust level of health-related information is higher than that of property-related information. Negative information wins more trust than positive information.(2) With regard to conformity extent and decision-making speed, there are differences between decision based on property information and decision based on health information. When the valence of information is positive, there are no differences between two types of decision making on conformity extent and decision-making speed. When the valence of information is negative, higher conformity extent and faster decision-making speed are observed towards the decision based on health information than that based on property information.(3) The neural mechanism of conformity behavior based on property information can be reflected by N400, error related negativity (ERN), feedback related negativity (FRN) and P300component. In the decision of stock purchase, people with counter-conformity behavior perceives and monitors more conflict than people with conformity behavior in the information perception stage and decision making stage, which are reflected by N400and ERN. In the outcome evaluation stage, there are differences in evaluation of outcome between conformity and counter-conformity behavior. Counter-conformity individuals pay more attention to the outcome, and have stronger emotional response to it; Conformity behavior can attenuate individual emotional experience, which is reflected by FRN and P300.(4) The neural mechanism of conformity behavior based on health information can be reflected by N400, late positive potential (LPP), ERN and N400(FRN). In the background of food evaluation or purchase, there are conflicts in the perception of food with health risk information, and different kinds of health risk elicit different emotional response, which are reflected by N400and LPP. In the decision-making stage, people with counter-conformity behavior monitor more conflicts than conformity, which is reflected by ERN component. In the outcome evaluation stage, different kinds of feedback are perceived differently for counter-conformity behavior, but not for conformity behavior, which is reflected by N400(FRN). In addition, food physical information (taste) affects perception of health risk information, which modulates the amplitude of N400component.(5) Gender has effect on the trust level of information. Compared with male, female trust health information more, but trust property information less. However, gender has no stable significant effect on informational conformity and counter-conformity effect.(6) Investment experience has significant effects on informational conformity in the behavioral level. Individuals with no investment experience have higher conformity extent, and are more risk-seeking. This paper is mainly based on stock-buying decision making and food-buying decision making in order to study informational conformity from both behavioral and neural level. There are several innovative points as follows.(1) This study fills the blank of comparative research on conformity behavior under different decision-making scenarios. Previous studies on conformity are performed mainly in different academic fields, with few researches across them. This paper compares conformity effect in property-related decisions (stock-buying decision making) with health-related decisions (food-buying decision making), which bridges the gap. It suggests that relevant government departments pay more attention on negative health information and give high priority to put limited recourses to deal with such problems, because negative health information is more likely to cause panic or instability to the society.(2) This study uses ERPs experimental research method to explain the existence of conformity effect from the perspective of neuroscience. Previous researches on the reasons of conformity have been focused on group pressure, information asymmetry and so on; and counter-conformity has been explained by the need for uniqueness. But these interpretations are subjective descriptive explanations. This study integrates neuroscience perspective and finds that conformity effect is induced since individuals perceive conflict when conducting counter-conformity behavior. Therefore, the individuals should pay a certain amount of cognitive resources and attention to overcoming the conflict in order to achieve counter-conformity. Thus generally, the degree of conformity is greater than that of counter-conformity.(3) This study observes the differences on the evaluation of feedback outcomes after conducting conformity behavior and counter-conformity behavior, and provides evidences from neuroscience perspective. Previous studies on conformity and counter-conformity mainly focus on their definition, motivation and influence factors. Few researches are done on evaluating the outcome after conformity and counter-conformity behavior. The study uses ERPs experimental method and shows differences in subjective evaluation of the feedback towards conformity and counter-conformity behavior. Conformity behavior can attenuate individual emotional experience for negative outcome, while counter-conformity behavior gives rise to the likelihood of more attention towards the outcome, and elicits stronger emotional response to the outcome.(4) This study suggests that food taste modulates the amplitude of N400elicited by health risk information, which provides an interesting insight into N400component. Previous researches on N400mainly focus on match between words or between words and contexts. And N400primarily reflects mismatch or conflict. In this study, N400is evoked by the conflict between food and health risk, but food taste can modulate N400component, which is a new insight into N400.更多还原