本研究旨在透過期望地位的觀點，剖析學生在不同性質的討論活動中互動的平等性。基於此一旨趣，本研究首先從社會學、社會心理學、合作學習、社會計量學等理論的文獻評析，探討學生在互動時可能產生的狀況，並將其應用於探討小組互動的平等性問題，最後試圖找出改變小組互動平等性的可能辦法。根據上述的結果，設計「對照組」與「實驗組」兩類教學討論進行實徵研究，並以錄影、錄音的方式蒐集所需資料。於此，本研究提出以下結論：
一、 研究中的兩個班級，在研究前後，其班級結構穩定性很高。而學術地位與同儕地位的相關性也都達到了顯 著水準。因此施以小組活動的方式，對班級結構的影響不大。
二、 在一個自然、未經處置的小組討論中存在著互動不平等的現象，即高地位的學生在各方面的表現皆比低地 位的學生來得傑出，驗證了「權力與尊榮的秩序（power and prestige order）」是很穩定的。而且大致上也 符合了「基本期望假設」。根據本研究的發現與歸納，可以進一步的提出教室中的基本期望假設。
三、 對於以實驗組進行教學討論的方式，來改變教室中基本期望假設的嘗試，可以得到以下結果：學生的互動 仍然維持著不平等性，因此驗證了「權力與尊榮的秩序難以改變」的命題。但是經過了這個教學處置後， 中、低地位的學生與在對照組之下的表現相比較之後，在許多方面有了明顯的進步。因此，在不損及高地 位學生權益的前提之下，此法的確有其功效。於此，根據本研究的發現與歸納，可以針對教室中的基本期 望假提出更進一步的修正。
四、 單一能力的改良任務（實驗組）對互動平等性的改變程度較有限，所以一個多元能力任務的開發、以及強 調科學教室中的多元價值將是達到互動平等性的重要課題。
五、 如欲使用靶狀圖去瞭解學生在不同的任務中表現是否有所差異，除非是學生的表現有很大的改變，否則此 法無法達成目標。因為它很難描述出學生在不同任務中的進步或退步情形。
六、 經由學生的對話分析，可以得到由量的分析所簡併的許多訊息。除此之外，由對話分析過程，可以發掘許 多由量的分析所無法發現的問題。是以，倘若能更深入地應用此類的研究取向於教室同儕互動中，例如話 語分析（discourse analysis），相信對研究者或教師而言，一定能夠提供許多研究與教學上的建議。而本 研究關於學生的對話分析結果顯示，「地位」的差異對於小組學生的互動的確扮演著很重要的角色，它影 響了學生的參與度、學習興趣…等。因此，這對科學教育實務而言，有著不可忽視的重要性。
最後，本研究針對研究結果提出相關的討論與建議。

The purpose of the study was to analyze the equality of peer interactions in different kinds of group discussions from the perspective of expectation states theory(E.S.T.). The study began with a literature review from sociology, social psychology, cooperative learning, sociometry and discussed the possible situations in students' interacions which were applied into discussing the equality of interactions within group. Finally, the researcher tried to find the way improving the equality within group. Based on the discussions above, the researcher took two kinds of teaching approaches in the empirical study--the first was controlled teaching and peer discussions, the second was experimental teaching and peer discussions--and collected data in the forms of audio and video tape-recording. The findings of this study were summarized as follows:
1. The classroom structures of two classes were still stable after this study. And the correlation of the academic and the peer status had reached the level of significance. So, the influence to classroom structures through group activity was not salient.
2. There were inequalities in a natural, undisposed group discussions. It was to say that the high status students' performances were better than the low status students, and then proved the power and prestige order within group was very stable. So, it was accordant with the basic expectations assumptions. Based on the research findings, advanced suggestions about basic expectations assumptions in classroom were proposed.
3. The results of attempt of changing basic expectations assumptions in classroom through experimental teaching and peer discussions were: the inequalities still existed among students' interactions, and hence verified the proposition of the power and prestige order was difficult to change. But after this disposition, the performances of the medium and low status students had improved obviously in a lot of aspects than that in the controlled teaching and peer discussions. So, in the premiss of not harming the high status students' advantage, the experimental teaching and peer discussions were really feasible. Hence, based on the experimental teaching and peer discussions and basic expectations assumptions in classroom , an advanced suggestion was proposed.
4. The extents of improving equality by the task that stressed on single ability (experimental teaching and peer discussions) were limited, so it was important for improving equalities by developing multiple ability tasks and stressing on the multi-values in science classroom.
5. Unless the student's performances had obviously changed in different tasks, the target sociograms couldn't show the differences of the student's performance between these tasks. Because the sociograms couldn't describe the progress or regress of one student's performances in the different tasks.
6.Through the dialogue analysis could get lots of informations degenerated by quantity analysis. Besides, through the process of dialogue analysis could find many problems that quantity analysis couldn't. So, if we could lucubrated this kind of research method and applied it into the peer interactions, such as discourse analysis, it must have many
suggestions and implications for researcher and teacher. The results of students' dialogue analysis showed that the status played an important role for students' interaction in groups, it influenced students' participation rates, interests, and etc. Hence, it was very important to the practice of science education.
Finally, based on research findings of this study, further avenues of research in the field were discussed and suggested.

中文部分：
宋玉亭、談漵梅、盧民強、嚴導淦、曹運祥主編（1995）：物理學發展史上的里程碑。新竹：凡異出版社。
李佳玲（1995）：國中理化試行合作學習之研究。國立彰化師範大學科學教育研究所碩士論文。未出版。
李郁文（1998）：團體動力學：群體動力的理論與實務。台北：桂冠圖書公司。
李美枝（1993）：從有關公平判斷的研究結果看中國人之人己關係的界限。本土心理學研究，1，pp. 267-300 。
吳武典 （1989）：社會計量法。載於楊國樞等人主編，社會及行為科學研究法下冊（pp. 677-719）。台北：東 華書局。
林芬遠（1997）：國中生物課教室口語之探究。國立彰化師範大學科學教育研究所碩士論文。未出版。
林清山（1992）：心理與教育統計學。台北：東華書局。
周玉秀（1996）：數學課堂上反映的兒童學習現象－臨床教學研究札記。台北師院學報，9，pp. 53-82。
周立勳（1996）：誰較有可能問問題？國小學童課業尋盼相關因素之分析。嘉義師院學報，10，pp. 261-295。
周雅容（1996）：象徵互動論與語言的社會意涵。載於胡幼慧主編，質性研究：理論、方法及本土女性研究實 例。台北：巨流圖書公司。
邱穗中、葉連祺（1995）：雙向度社會計量地位分類方法之比較－以國小學生為例。國立政治大學「教育與心 理研究」，18，pp. 19-50。
金觀濤（1988）：人的哲學。台北：台灣商務印書館，pp. 28-29。
洪世仰（1998）：自我應驗預言作用的理論與應用。教育研究雙月刊，60，pp. 67-78。
洪振方（1994）：從孔恩異例的認知與論證探討科學知識的重建。國立台灣師範大學科學教育研究所博士論文 。未出版。
洪儷瑜、涂春仁（1996）：Coie & Dodge社會計量地位分類公式之修正。中國測驗學會測驗年刊，43，pp. 103-114。
郭重吉（1992）：從建構主義的觀點探討中小學數理教學的改進。科學發展月刊， 20（5），pp. 548-570。
郭重吉、許玫理（1992）：從科學哲學觀點的演變探討科學教育的過去與未來。彰化師範大學學報，3，pp. 531-561。
陳淑敏（1995）：社會互動對認知發展的影響。八十四學年度師範學院教育學術論文發表會論文集（4），pp. 110-122。
國立編譯館（1992）：高級中學物理第三冊（七版）。台北：國立編譯館主編。
國立編譯館（1998）：國民中學理化第一冊（初版）。台北：國立編譯館主編。
曾守恆（1997）：「同儕科學家像」對科學知識重建過程的影響分析。國立台灣師範大學科學教育研究所碩士 論文。未出版。
黃光國（1995）：知識與行動：中華文化傳統的社心心理詮釋。台北：心理出版社。
黃忠雄（1997）：國中生「同儕科學家意象」對科學概念合理性判斷的影響。國立台灣師範大學地球科學研究 所碩士論文。未出版。
黃俊儒、楊文金（1997）：由科學本質觀的流變來看人與知識間的關係及其對科學教育的意涵。趙教授金祁榮 退學術研討會論文集：我國科學教育的回顧與前瞻，pp. 333-349。
黃德祥（1991）：社會計量地位分類之研究。中國測驗學會測驗年刊，38，pp.53-69。
葉連祺（1996a）：構建一種多功能取向的社會計量資料分析工具－社會計量剖面圖。國民教育研究學報，2， pp. 49-79。
葉連祺（1996b）：三種社會計量地位分類方法之探析。初等教育學刊，5，pp. 263-304。
葉連祺（1996c）：建構一種以互選關係為基礎的靶狀圖。國教學報，8， pp. 73-97。
葉蓉樺、羅文杰和楊文金（1998）：國小五年級學童：「同儕科學家意象」的發展初探。第十四屆科學教育學 術研討會短篇論文彙編，pp. 639-646。
楊文金（1996a）：比較、社會比較、與科學學習的動機。科學教育月刊，195，pp.2-16。
楊文金（1996b）：「同儕科學家意像」對訊息合理性判斷的影響。論文發於1996年中華民國物理教育年會。 台北：國立台灣師範大學。
楊文金（1997）：社會類別對信念選擇的影響分析。科學教育學刊，5（1），pp. 1- 21。
楊文金（1998a）：同儕互動的社會本質。屏師科學教育，8，pp. 2-11。
楊文金（1998b）：從「社會認同」探討「科學家意像」的意義。科學教育月刊，206，pp.3-10。
楊文金（1998c）：「同儕科學家意像」對訊息合理性判斷的影響分析。師大學報：科學教育類，43（1）， pp.1-17。
楊文金（1999a）：「學生像科學家」的類比分析。論文發於1999科學史、哲與科學教育學術研討暨研習會。 高雄：國立高雄師範大學。
楊文金（1999b）：「期望地位」對同儕互動的影響分析。未發表。
楊宏珩（1997）：行動研究：以高中化學教學試行合作學習為例。國立彰化師範大學科學教育研究所碩士論文 。未出版。
楊莉川（1997）：從社會認同理論探討高中生傾向科學的態度。國立台灣師範大學科學教育研究所碩士論文。 未出版。
楊瑩（1998）：當前台灣地區教育機會均等問題的探討。載於中華民國比較教育學會、中國教育學會主編：社 會變遷中的教育機會均等（pp. 1-28）。台北：揚智書局。
熊同鑫（1998a）：語言在自然科教室內的意涵：一間後山教室內教學活動的記事。台東師院學報，9，pp. 1-36 。
熊同鑫（1998b）：語言在自然科教室的角色：學童對話分析。第十四屆科學教育學術研討會短篇論文彙編， pp. 107-113。
蔣佳玲（1995）：從符號互動論的觀點探討國小學生科學家形象的建構。國立彰化師範大學科學教育研究所碩 士論文。未出版。
蔣佳玲（1999）：從權力的觀點探討學生在小組互動中科學知識的建構。國立彰化師範大學科學教育研究所博 士論文。未出版。
蔣佳玲、郭重吉（1997）：同儕間科學問題討論中的合作與權力關係。第十三屆科學教育學術研討會短篇論文 彙編，pp. 627-634。
蔣佳玲、郭重吉（1998）：應用社會圖探討小組中的互動關係。第十四屆科學教育學術研討會短篇論文彙編， pp. 285-292。
魏明通（1997）：科學教育。台北：五南圖書出版公司。
謝廣全（1994）：最新實用心理與教育統計學。高雄：復文書局。
羅文杰（1997）：兩種「班級結構」分類法在國小「同儕科學家意象」的維度上之比較分析。國立台灣師範大 學科學教育研究所碩士論文。未出版。

英文部分：
Alexopoulou, E., & Driver, R. (1996). Small-group discussion in physics: Peer interaction modes in pairs and fours. Journal of research in science teaching,33(10), pp. 1009-1114.
Aronson, E., & Patnoe, S. (1997). The jigsaw classroom: Building cooperation in the Classroom(2nd ed.). New York: Longman.
Aronson, E., Stephan, C., Sikes, J., Blaney, N., & Snapp, M. (1978). The jigsaw classroom. Beverly Hills, CA: Sage.
Aronson, E., Wilson, T. D., & Akert, R. M. (1994). Social psychology. HarperCollins College. （李茂興、余伯泉譯， 1995，社會心理學。台北：揚智文化、弘智文化）
Augoustinos, M., & Walker, I.(1995). Social cognition：An intergrated introduction. London：SAGE.
Berger, J. (1974). Expectation states theory: A theoretical research program. In J. Berger, T. L. Conner, M. H. Fisek(Eds.), Expectation states theory: A theoretical research program(pp. 3-22). Cambridge, MA: Winthrop.
Berger, J., Cohen, B. P., & Zelditch, M., JR. (1966). Status characteristics and expectation states. In J. Berger, M. Zelditch, JR. , B. Anderson (Eds.), Sociological theories in progress,Vol 1 (pp. 29-46). Boston: Houghton Mifflin.
Berger, J., Conner, T. L., (1974). Performance expectations and behavior in small groups: A revised formulation. In J. Berger, T. L. Conner, M. H. Fisek(Eds.), Expectation states theory: A theoretical research program(pp. 85-109). Cambridge, MA: Winthrop.
Berger, J., Fisek, M. H. (1974). A generalization of the theory of status characteristics and expectation states. In J. Berger, T. L. Conner, & M. H. Fisek (Eds), Expectation states theory: A theoretical research program(pp. 163-205). Cambridge, MA: Winthrop.
Berger, J., Fisek, M. H., Norman, R. Z., & Wagner, D. G.,(1985). Formation of reward expectations in status situations. In J. Berger & M. Zelditch Jr. (Eds.). Status, Rewards, and Influence：How Expectations Organize Behavior(pp. 215-
261). CA: Jossey-Bass.
Berger, J., Fisek, M. H., Norman, R. Z., & Zelditch, M., Jr. (1977). Status characteristics and social interaction. New York: Elsevier.
Berger, J., Wagner, D. G., Zeldtch, M. Jr. (1985). Expectation States Theory：Review and Assessment. In J. Berger & M. Zelditch Jr. (Eds). Status, rewards, and influence: How expectations organize behavior(pp. 1-72). CA: Jossey-Bass.
Bianchini, J. A.(1997). Where knowledge construction, equity, and context intersect：Student learning of science in small groups. Journal of Research in Science Teaching, 34(10), pp. 1039-1065.
Cazden, C. B. (1988). Classroom discourse: The languade of teaching and learning. Portsmouth, NH: Heinemann.（蔡敏 玲、彭海燕譯，1998，教室言談：教與學 的語言。台北：心理出版社）
Cohen, E. G.(1986). Designing groupwork: Strategies for heterogeneous classrooms. New York: Teachers College Press.
Cohen, E. G. (1997). Understanding status problems: Sources and consequences. In E. G. Cohen, R. A. Lotan (Eds.), Working for equity in heterogeneous classrooms(pp. 61-76), New York: Teachers College Press.
Cohen, E. G., & Lotan, R. A. (1995). Producing equal-status interaction in the Heterogeneous classroom. American Educational Research Journal, 32(1), pp. 99-120.
Cohen, E. G., & Lotan, R. A. (Eds.)(1997a). Working for equity in heterogeneous classroom: Sociological theory in action. New York：Teachers College Press.
Cohen, E. G., & Lotan, R. A. (1997b) . Raising expectations for competence: The effectiveness of status intervention. In E. G. Cohen, R. A. Lotan (Eds.), Working for equity in heterogeneous classrooms (pp. 77-91), New York: Teachers College Press.
Cohen, E. G., Lotan, R. A., & Catanzarite, L. (1990). Treating status problems in the cooperative classroom. In S. Sharan (Ed.), Cooperative learning: Theory and research(pp. 203-230). New York: Praeger.
Conner, T. L., (1985). Response latencies, performance expectations, and interaction patterns. In J. Berger & M. Zelditch Jr. (Eds.), Status, Rewards, and Influence：How Expectations Organize Behavior(pp. 189-214). CA: Jossey-Bass.
Damon, W., & Phelps, E. (1989). Critical distinctions among three approaches to peer education. Internationl Journal of Eductional Research, 13, pp. 9-19.
Daniels, H. (Ed.) (1993). Charting the agenda: Educational activity after Vygotsky. New York: Routledge.
Driver, R. (1989). The construction of scientific knowledge in school classrooms. In R. Millar (Ed.), Doing science: Images of science in science education. PA: Falmer.
Edwards, D., & Mercer, N. (1987). Common knowledge: The development of understanding in the classroom. London: Routledge.
Flavell, J. H. (1987). Speculations about the nature and development of metacognition, In F. E. Weinert & R. H. Kluwe (Eds.), Metacognition, motivation, and understanding. Hillsdale, New Jersey: Lawrence Erlbaum Associates.
Geelan, D. R. (1997). Epistemological anarchy and the many forms of constructivism, Science & Education, 6, pp. 15-28.
Hertz-Lazarowitz, R. (1992). Understanding interactive behaviors: Looking at six mirrors of the classroom. In R. Hertz-Lazarowitz, & N. Miller (Eds.), Interaction in cooperative groups:The theoretical anatomy of group learning(pp. 71-101), Cambridge University Press.
Hertz-Lazarowitz, R., Kirkus,V. B., & Miller, N. (1992). Implications of current research on cooperative interaction for classroom application. In R. Hertz-Lazarowitz, & N. Miller (Eds.), Interaction in cooperative groups:The
theoretical anatomy of group learning(pp. 253-280), Cambridge University Press.
Howell, D. C. (1997). Statistical methods for psychology (4th ed.). CA: Wadsworth.
Johnson, D. W., & Johnson, R. T. (1992). Positive interdependence: Key to effective cooperation. In R. Hertz-Lazarowitz, & N. Miller (Eds.), Interaction in cooperative groups:The theoretical anatomy of group learning(pp. 174-199), Cambridge University Press.
Kelly, G. J., & Crawford, T. (1997). An ethnographic investigation of the discourse processes of school science. Science Education, 81, pp. 533-559.
Knight, G. P., & Bohlmeyer, E. M. (1990). Cooperative learning and achievement: Methods for assessing causal mechanisms. In S. Sharan(Ed.), Cooperative learning: Theory and research(pp. 1-22). New York: Praeger.
Lamberigts, R. (1990). Evaluation of task interdependence and peer tutoring in a compact cooperative learning technique. In H. Mandl, E. D. corte, N. Bennett, & H. F. Friedrich(Eds.), Learning and instruction: European research in an international context, volume 2.1: Social and cognitive aspects of learning and instruction(pp. 95-112). New York: Pergamon.
Lazarowitz, R., Hertz-Lazarowitz, R., Baird, J. H. (1994). Learning sccience in a cooperative setting: academic achievement and affective outcomes. Journal of research in science teaching, 31(10), pp. 1121-1131.
Lazorowitz, R., Hertz-Lazorowitz, R., Baird, J. H., & Bowlden, V. (1988). Academic achievement and on-task behavior of high school biology students instructed in a cooperative small investigative group. Science education, 72(4), pp. 475-487.
Lazarowitz, R., & Karsenty, G. (1990). Cooperative learning and students' academic achievement, process skills, learning environment, and self-esteem in tenth-grade biology classrooms. In S. Sharan(Ed.), Cooperative learning: Theory and
research(pp. 123-149). New York: Praeger.
Leal-Idrogo, A. (1997). The effect of gender on interaction, friendship, and leadership in elementary school classrooms. In E. G. Cohen & R. A. Lotan (Eds.). Working for equity in heterogeneous classrooms: Sociological theory in practice. NY: Teachers College Press.
Lemke, J. L. (1990). Talking science: Language, learning, and value. Norwood, NJ：Ablex.
Light, D. Jr. & Keller, S. (1985). Sociology. New York: Mcgraw-Hill.（林義男譯，1995，社會學(上)、(下)。台北： 巨流圖書公司）
Lockheed, M. E., Harris, A. M., Nemceff, W. P. (1983). Sex and social influence: Does sex function as a status characteristic in mixed-sex groups of children. Journal of Educational Psychology, 75(6), pp. 877-888.
Lou, Y., Abrami, P. C., Spence, J. C., Poulsen, C., Chambers, B., & d'Apollonia, S. (1996). Within-class grouping: A meta-analysis. Review of educational research, 66(4), pp. 423-458.
Loving, C. C. (1991). The scientific theory profile: A philosophy of science model for science teachers. Journal of research in science teaching, 28(9), pp. 823-838.
McCarthey, S. J., & McMahon, S. (1992). From convention to invention: Three approaches to peer interactions during writing. In R. Hertz-Lazarowitz, & N. Miller(Eds.). Interaction in cooperative groups: The theoretical anatomy of
group learning(pp. 17-35). Cambridge University Press.
Mulkay, M. J. (1979). Science and the sociology of knowledge. London: Gregg Revivals. （蔡振中譯，1991，科學與知 識社會學。台北：巨流）
National reseach council(1996). National science education standard. Washington, DC: National Academy Press.
Posner, G. J., Strike, K. A., Hewson, P. W., & Gertzog, W. A. (1982). Accommodation of a scientific conception: Toward a theory of conceptual change. Science Education, 66, pp. 211-228.
Richmond, G., & Striley, J. (1996). Making meaning in classroom：Social processes in Small group discourse and scientific knowledge building. Journal of Research in Science Teaching, 33(8), pp. 839-858.
Rosenholtz, S. J. (1985). Modifying status expectations in the traditional classroom. In J. Berger & M. Zelditch Jr. (Eds.), Status, rewards, and influence：How expectations organize behavior(pp. 445-470). CA: Jossey-Bass.
Rosenthal, R., & Rosnow, R. L. (1991). Essentials of behavioral research: Methods and data analysis (2nd ed.). New York: Mcgraw-Hill.
Roth, W. -M. (1995). Authentic School Science: Knowledge and learning in open-inquiry science laboratories. Boston: Kluwer Academic Publishers.
Roth, W. -M. (1995). Teacher questioning in an open-inquiry learning environment: Interactions of context, content, and student responses. Journal of research in science teaching, 33, pp. 709-736.
Saxe, G. B., Gearhart, M., Note, M., & Paduano, P. (1993). Peer interaction and the development of mathematical understandings: A new framework for research and educational practice. In H. Daniels(Ed.). Charting the agenda: Educational activity after Vygotsky(pp. 107-144). New York: Routledge.
Shepardson, D. P. (1996). Social interactions and the mediation of science learning in two small groups of first-grader. Journal of research in science teaching, 33(2), pp. 159-178.
Slavin, R. E.(1983). Cooperative learning. New York: Longman.
Slavin, R. E.(1987). Developmental and motivational perspective on cooperative learning: A reconciliation. Child Development, 58, pp. 1161-67.
Slavin, R. E.(1988). Cooperative learning and student achievement. Educational Leadership, 46(2), pp. 31-33.
Slavin, R. E. (1992). When and why does cooperative learning increase achievement？ Theoretical and empirical perspectives. In R. Hertz-Lazarowitz, & N. Miller(Eds.). Interaction in cooperative groups: The theoretical anatomy of
group learning(pp. 145-173). Cambridge University Press.
Solomon, J. (1987) Social Influences on the Construction of Pupils' Understanding of Science, Studies in Science Education, 14, pp. 63-82.
Solomon, J. (1994a). The Rise and Fall of Constructivism﹐Studies in Science Education﹐23, 1-19.
Solomon J.(1994b). Group discussions in the classroom.In R. Levinson(Ed.).Teaching Science.London：Routledge.
Strauss, A., & Corbin, J. (1990). Basics of qualitative research: Grounded theory procedures and thchniques. Lodon: Sage. （徐宗國譯，1997，質性研究概論。台北：巨流圖書公司）
Steiner, I. D. (1972). Group process and productivity. New York and London: Academic Press.
von Glaserfeld, E. (1993). Questions and answers about radical constructivism. In K, Tobin(Ed.). The practice of constructivism in science education. NW, Washington：AAAS Press.
Wagner, D. G., & Berger, J. (1993). Status characteristics theory：the growth of a program. In J. Berger & M. Zelditch, Jr.(Eds.). Theoretical research programs： studies in the growth of theory. CA：Stanford University Press.
Webb, N. M. (1989). Peer interaction and learning in small groups. International journal of educational research, 13, pp. 21-39.
Webb, N. M. (1992). Testing a theoretical model of student interaction and learning in small groups. In R. Herttz-Lazarowitz, & N. Miller (Eds.), Interaction in cooperative groups:The theoretical anatomy of group learning(pp. 102-119), Cambridge University Press.
Wertsch, J. V., & Stone, C. A.(1985). The concept of internalization in Vygotsky's account of the genesis of higher mental functions. In J. V. Wertsch(Ed.). Culture, communication, and cognition: Vygotsky perspectives. New York: Cambridge
University Press.