CONTENTSxviiInferential Statistics 458Sampling458The Distribution of Sample Means460Testing Hypotheses463Tests forDifferences between Two Groups469tTest473Magnitude of Effect476The Analysis of Variance477XTest for Independence486Misuses of Statistics487Use of Small or Biased Samples5488Absent orInappropriateComparisons489The Gambler's Fallacy490Summary491KeyTerms492Web Connections492494APPENDIXCSTATISTICALTABLESTableAProportions of Area under the Normal Curve495TableBCritical Values of the UStatistic of theMann-WhitneyTest498TableCDistribution for the Sign Test500Table DCritical Values of Wilcoxon's TStatistic for the Matched-Pairs Signed-Ranks Test502TableECritical Values oft 503Table F504Critical Values of the F DistributionTableGCritical Values of the x Distribution508Table HRandom NumbersS509511REFERENCESGLOSSARY528542NAMEINDEX545SUBJECTINDEX
CONTENTS xvii Inferential Statistics 458 Sampling 458 The Distribution of Sample Means 460 Testing Hypotheses 463 Tests for Differences between Two Groups 469 t Test 473 Magnitude of Effect 476 The Analysis of Variance 477 2 Test for Independence 486 Misuses of Statistics 487 Use of Small or Biased Samples 488 Absent or Inappropriate Comparisons 489 The Gambler’s Fallacy 490 Summary 491 Key Terms 492 Web Connections 492 APPENDIX C STATISTICAL TABLES 494 Table A Proportions of Area under the Normal Curve 495 Table B Critical Values of the U Statistic of the Mann-Whitney Test 498 Table C Distribution for the Sign Test 500 Table D Critical Values of Wilcoxon’s T Statistic for the Matched-Pairs Signed-Ranks Test 502 Table E Critical Values of t 503 Table F Critical Values of the F Distribution 504 Table G Critical Values of the 2 Distribution 508 Table H Random Numbers 509 REFERENCES 511 GLOSSARY 528 NAME INDEX 542 SUBJECT INDEX 545 59533_01_fm_pi-xxiv.indd xvii 9533_01_fm_pi-xxiv.indd xvii 3/6/08 7:06:50 PM /6/08 7:06:50 PM
PREFACEThe term experimental psycbology used to denote only afew selected topics in psychology.In, say,1930, experimentswere conducted to understand sensation, perception,learning,memory,and a few other topics. The situation is quite differenttoday:Experimental methods are used to investigate social psy-chology, developmental psychology, individual differences, andmanyothertopics(such as environmental psychology)thatwerenot considered in psychology's vision eighty years ago. The useof experimental methodshasexpanded to includemosttopicsin the field. Writing a textbook aimed at this topic has thereforebecome an increasing challenge.This textbook is the ninth edition of a book first publishedin1978.Each edition has seen both major and minor changes inresponse to students' and professors' comments, and this edition isno exception.Readers familiar with the previous edition will findchanges in every chapter. We have tried to blend the best aspectsofthepreviouseighteditionswithnewfeaturestomakethebookeven more appealing. (We describe the changes in more detailbelow.)We arepleased thatthe continued popularity of thistexthas permitted us to produce this new edition, because we thinkwe have been able to improve it, and we have enjoyed workingon it again.The titleExperimental Psycbology has appeared on manytextbooksthathavebecome classics,beginning withE.B.Titchener'spair in theearly1900s,throughWoodworth's1928textand itsrevision(Woodworth&Schlossberg,1954),and finally tothosebooksbyOsgood(1953)andUnderwood(1966).Allthesebooksprovided an introduction to research methodology,but they did soin the context of fundamental research in experimental psychol-ogy.Thebooks wereprimarilyabout the content of experimentalpsychology, with an emphasis on the research methods used toacquiretheknowledge.Weseeourtextbook asfirmlywithinthistradition, even if much less encyclopedic than the great booksmentionedaboveToday this approach is unique; during the 1970s and the1980s, many"research methods"texts appeared that orga-nize the subject matter quite differently. Instead of providingxix
xix PREFACE The term experimental psychology used to denote only a few selected topics in psychology. In, say, 1930, experiments were conducted to understand sensation, perception, learning, memory, and a few other topics. The situation is quite different today: Experi mental methods are used to investigate social psychology, developmental psychology, individual differences, and many other topics (such as environmental psychology) that were not considered in psychology’s vision eighty years ago. The use of experimental methods has expanded to include most topics in the fi eld. Writing a textbook aimed at this topic has therefore become an increasing challenge. This textbook is the ninth edition of a book fi rst published in 1978. Each edition has seen both major and minor changes in response to students’ and professors’ comments, and this edition is no exception. Readers familiar with the previous edition will fi nd changes in every chapter. We have tried to blend the best aspects of the previous eight editions with new features to make the book even more appealing. (We describe the changes in more detail below.) We are pleased that the continued popularity of this text has permitted us to produce this new edition, because we think we have been able to improve it, and we have enjoyed working on it again. The title Experimental Psychology has appeared on many textbooks that have become classics, beginning with E. B. Titchener’s pair in the early 1900s, through Woodworth’s 1928 text and its revision (Woodworth & Schlossberg, 1954), and fi nally to those books by Osgood (1953) and Underwood (1966). All these books provided an introduction to research methodology, but they did so in the context of fundamental research in experimental psychology. The books were primarily about the content of experimental psychology, with an emphasis on the research methods used to acquire the knowledge. We see our textbook as fi rmly within this tradition, even if much less encyclopedic than the great books mentioned above. Today this approach is unique; during the 1970s and the 1980s, many “research methods” texts appeared that organize the subject matter quite differently. Instead of providing 59533_01_fm_pi-xxiv.indd xix 9533_01_fm_pi-xxiv.indd xix 3/6/08 7:06:50 PM /6/08 7:06:50 PM
PREFACEXXmethodology in the context in which it is used, these books treat methodologicaltopics (e.g., between-subjects designs, small-n designs) as chapter titles and in-troduce content examples to flesh out the discussion of the methods. This is alsoan excellent approach, and we have produced another text that embodies thismethod(ResearcbMetbods inPsycbology,byElmes,Kantowitz,and Roediger,alsopublished by Wadsworth).However, Experimental Psycbology seeks to providean integrated blend of content and methodology, with methods discussed in the con-text of actual research. Primary differences between our text and those of our prede-cessors in this tradition are that ourapproach isto select particularexamples thatbestillustrate the methodological point under consideration and that our book is intendedmostly for an undergraduate audience with only a first course in psychology as abackground.We should note one point about terms in our book. In 1994, the PublicationManual oftbeAmerican Psycbological Associationrecommended thatthetraditionalterm subjects, which had been used for over a century to refer to people who weretested in psychological research, be changed to participants.This change receiveda mixed reaction in the research community,and some other organizations thatpublish psychology journals did not go along.For example, the Psychonomic Soci-ety permits use of either term in papers published in their journals.In addition, thecopyeditors of the American Psychological Association journals do not insist thatparticipants be used as the favored term, but rather encourage its use. Because thesituation is unsettled, we have followed the convention of using both subjects andparticipants when referring to people in psychological research. Wetend to usesubjects when referring to non-human animals in research, but we use both termswhen referring to humans. The usage in our text therefore reflects current practicein the field at large.TEXT ORGANIZATIONThe philosophy of the text remains unchanged. As with the first eight editions, wehave striven to achieve an integrated treatment of experimental psychology withaseamless link binding methodology and content. The book includes two main parts.The first five chapters constitute Part One, Fundamentals of Research, and discusssome basic methodological preliminaries that students need. In these chapters wedescribe some general aspects of science and theory construction;the features of(and differences among) observational, correlational, and experimental methods(with an emphasis on the last); ethical issues in research; and how to read and writeresearch reports.In the remaining ten chapters, which make up Part Two, Principles and Practicesof Research,weflesh outthebarebonesprovided inPart Oneby illustrating method-ological topics in the context of actual research problems. The chapters are providedwith contenttitles (forexample, Perception), and some content is covered in its ownright, but the main purpose of the chapters is to present methodological topics in thecontext of actual research.This organization reflects our belief that the best way toprovide students with an understanding of methodology is to embed it in the contextof real problems that occur in conducting research. Methodology does not exist in avacuum, but is devised to solve concrete research problems.We hope that presenting
methodology in the context in which it is used, these books treat methodological topics (e.g., between-subjects designs, small-n designs) as chapter titles and introduce content examples to fl esh out the discussion of the methods. This is also an excellent approach, and we have produced another text that embodies this method (Research Methods in Psychology, by Elmes, Kantowitz, and Roediger, also published by Wadsworth). How ever, Experimental Psychology seeks to provide an integrated blend of content and methodology, with methods discussed in the context of actual research. Primary differences between our text and those of our predecessors in this tradition are that our approach is to select particular examples that best illustrate the methodological point under consideration and that our book is intended mostly for an undergraduate audience with only a fi rst course in psychology as a background. We should note one point about terms in our book. In 1994, the Publication Manual of the American Psychological Association recommended that the traditional term subjects, which had been used for over a century to refer to people who were tested in psychological research, be changed to participants. This change received a mixed reaction in the research community, and some other organizations that publish psychology journals did not go along. For example, the Psychonomic Society permits use of either term in papers published in their journals. In addition, the copyeditors of the American Psychological Association journals do not insist that participants be used as the favored term, but rather encourage its use. Because the situation is unsettled, we have followed the convention of using both subjects and participants when referring to people in psychological research. We tend to use subjects when referring to non-human animals in research, but we use both terms when referring to humans. The usage in our text therefore refl ects current practice in the fi eld at large. ▼ TEXT ORGANIZATION The philosophy of the text remains unchanged. As with the fi rst eight editions, we have striven to achieve an integrated treatment of experimental psychology with a seamless link binding methodology and content. The book includes two main parts. The fi rst fi ve chapters constitute Part One, Fundamentals of Research, and discuss some basic methodological preliminaries that students need. In these chapters we describe some general aspects of science and theory construction; the features of (and differences among) observational, correlational, and experimental methods (with an emphasis on the last); ethical issues in research; and how to read and write research reports. In the remaining ten chapters, which make up Part Two, Principles and Practices of Research, we fl esh out the bare bones provided in Part One by illustrating methodological topics in the context of actual research problems. The chapters are provided with content titles (for example, Perception), and some content is covered in its own right, but the main purpose of the chapters is to present methodological topics in the context of actual research. This organization refl ects our belief that the best way to provide students with an understanding of methodology is to embed it in the context of real problems that occur in conducting research. Methodology does not exist in a vacuum, but is devised to solve concrete research problems. We hope that presenting xx PREFACE 59533_01_fm_pi-xxiv.indd xx 9533_01_fm_pi-xxiv.indd xx 3/6/08 7:06:51 PM /6/08 7:06:51 PM
PREFACExximethods in the context of important content issues will help students to see the impor-tance of considering research methods.ChapterFormatThe chapters in Part Two all sharea common format.This parallel structure shouldhelp orient students to important features of the text that facilitate learning.Chapter Opening The chapters begin with an outline and quotation. Following a brieforientationtothecontentareaexploredinthechapter,thestudentwill comeacrossthefirst of several boxed inserts,whichreaders oftheprevious editionshavefound tobehelpful and which have therefore been carried over to the ninth edition.Introducing the Variables This feature quickly orients the student to those indepen-dent, dependent, and control variables commonly used in particular researchareas.Our coverage of these variables does not exhaust the possibilities, but does includesomeofthemostcommon ones.Experimental Topics and Research lllustrations This feature represents themain partof the chapter, in which two or three methodology issues are presented in the contextof an actual research problem. Thus, for example, in Chapter 10 we discuss the dif-ficultyof ceiling and floor effects inthe context ofa memoryexperiment in whichthisproblemactuallyarose.Manyoftheseexperimentaltopicshavebeenintroducedin Part One and are covered in more detail in Part Two. Some crucial topics are dis-cussed more than once in Part Two to ensurebetter comprehension.The content top-ics were chosen to be good vehicles for discussing the particular methodological pointunderconsideration.Thus,thecontenttopicsmaynotrepresentthemostimportanttopics in thesubject underdiscussion, nor do we intend our chapters to represent acompletesummaryofcontemporaryworkinthearea.Ourintentistoillustrateissuesof methodsinthecontextofactual researchproblemsthatareof interest.Twootherunique features appear toward the end of each chapter in Part Two.FromProblem To Experiment:The Nuts and Bolts In this section,we present the rationalebehind experimental design decisionshow many subjects should be used, why variableXis selected instead of variable Y,and so on-when hypothesesaretakenfromageneralform to the specifics of an experiment. These decisions are the "nuts and bolts" of experi-mental research. They are second nature to practicing experimenters and hence seldomarticulated in journal articles, but they may represent puzzles to those new to research.Psychology in Action This feature suggests safe and simple experimental demonstra-tions that require little or no equipment and that can be used in or out of class. For ex-ample,Chapter7includesademonstrationoftheStroopeffectandChapter14presentsmethods tomeasuretheeffects of noise on memory.End-of-Chapter Features Finally each chapter contains a summary in which the mainpoints of the chapter are reviewed, a set of key terms for review and study, and severaldiscussion questions
methods in the context of important content issues will help students to see the importance of considering research methods. Chapter Format The chapters in Part Two all share a common format. This parallel structure should help orient students to important features of the text that facilitate learning. Chapter Opening The chapters begin with an outline and quotation. Following a brief orientation to the content area explored in the chapter, the student will come across the fi rst of several boxed inserts, which readers of the previous editions have found to be helpful and which have therefore been carried over to the ninth edition. Introducing the Variables This feature quickly orients the student to those independent, dependent, and control variables commonly used in particular research areas. Our coverage of these variables does not exhaust the possibilities, but does include some of the most common ones. Experimental Topics and Research Illustrations This feature represents the main part of the chapter, in which two or three methodology issues are presented in the context of an actual research problem. Thus, for example, in Chapter 10 we discuss the dif- fi culty of ceiling and fl oor effects in the context of a memory experiment in which this problem actually arose. Many of these experimental topics have been introduced in Part One and are covered in more detail in Part Two. Some crucial topics are discussed more than once in Part Two to ensure better comprehension. The content topics were chosen to be good vehicles for discussing the particular methodological point under consideration. Thus, the content topics may not represent the most important topics in the subject under discussion, nor do we intend our chapters to represent a complete summary of contemporary work in the area. Our intent is to illustrate issues of methods in the context of actual research problems that are of interest. Two other unique features appear toward the end of each chapter in Part Two. From Problem To Experiment: The Nuts and Bolts In this section, we present the rationale behind experimental design decisions—how many subjects should be used, why variable X is selected instead of variable Y, and so on—when hypotheses are taken from a general form to the specifi cs of an experiment. These decisions are the “nuts and bolts” of experimental research. They are second nature to practicing experimenters and hence seldom articulated in journal articles, but they may represent puzzles to those new to research. Psychology in Action This feature suggests safe and simple experimental demonstrations that require little or no equipment and that can be used in or out of class. For example, Chapter 7 includes a demonstration of the Stroop effect and Chapter 14 presents methods to measure the effects of noise on memory. End-of-Chapter Features Finally each chapter contains a summary in which the main points of the chapter are reviewed, a set of key terms for review and study, and several discussion questions. PREFACE xxi 59533_01_fm_pi-xxiv.indd xxi 9533_01_fm_pi-xxiv.indd xxi 3/6/08 7:06:51 PM /6/08 7:06:51 PM
PREFACExxiiChapterSequenceAlthough students will be best served by reading Part One in correct serial order (espe-cially the first three chapters), those professors and students more interested in methodol-ogy than in content can ignore the chapter numbers in Part Two. The table that cross-listschapter numbers and experimental topics (to befound after the Preface)can be used todetermine the order in which chapters in Part Two are assigned. Thus, the instructor hasthe option of following a more- or less-traditional order or of creating a unique orderingbetter suited to his or her educational goals.Two lesser-used chapters that, however,may be quite necessaryfor some, are located in appendixes. Appendix A provides a briefsketch of the history of experimental psychology, and Appendix B contains a review ofbasic statistics.AncillariesAncillaries for this edition include the following:Instructor's Manual with Test Bank Resources forinstructors include chapter outlines,key terms, answers to discussion questions, lecture suggestions, demonstration suggestions,and“experimental dilemmas."Thetestbank containsmultiple-choice,true-falseand essay questions for each chapter. The test bank is also available electronically inthe ExamViewformat for the instructors to createtheirown tests/answers.Electronic Transparencies Many of the figures from the text are available as Power-Pointslides that can be downloaded and used in the classroom.BookCompanionWebsiteacademic.cengage.com/psychology/kantowitzThewebsitecontains several helpful features for both instructors and students.Instructors will beable to find teaching activities, chapter outlines, and chapters summaries. To aid stu-dents,thewebsitecontainsaglossary,flashcards,crosswordpuzzlestohelplearnkeyterms, and web links to Wadsworth Online Research Methods workshops, as well asother useful web links; suggestions for using Infotrac College Edition; and multiple-choice, matching,fll-in-the-blank, and essay tutorial quizzes that can be printed out oremailed directly to instructors.Changes inthe Ninth EditionUsers of the previous edition will discover many changes in the current edition. Webreferences have been updated for all chapters; while these were working in January2008, some will undoubtedly change during the life of this edition. These referencesguide readers to relevant discussions online, including the Wadsworth Online at TheWadsworthPsychologyStudyCenter.Inaddition,instructorsinNorthAmericawhohave specified that InfoTrac College Edition be packaged with this text have been pro-vided 4 months of free access to this extensive virtual libraryfor their studentsNew coverage and more recent references have been added in every chapter,and some chapters have been rebuilt to reflect the most recentfindings and topics
Chapter Sequence Although students will be best served by reading Part One in correct serial order (especially the fi rst three chapters), those professors and students more interested in methodology than in content can ignore the chapter numbers in Part Two. The table that cross-lists chapter numbers and experimental topics (to be found after the Preface) can be used to determine the order in which chapters in Part Two are assigned. Thus, the instructor has the option of following a more- or less-traditional order or of creating a unique ordering better suited to his or her educational goals. Two lesser-used chapters that, however, may be quite necessary for some, are located in appendixes. Appendix A provides a brief sketch of the history of experimental psychology, and Appendix B contains a review of basic statistics. Ancillaries Ancillaries for this edition include the following: Instructor’s Manual with Test Bank Resources for instructors include chapter outlines, key terms, answers to discussion questions, lecture suggestions, demonstration suggestions, and “experimental dilemmas.” The test bank contains multiple-choice, true-false, and essay questions for each chapter. The test bank is also available electronically in the ExamView® format for the instructors to create their own tests/answers. Electronic Transparencies Many of the fi gures from the text are available as PowerPoint® slides that can be downloaded and used in the classroom. Book Companion Website academic.cengage.com/psychology/kantowitz The website contains several helpful features for both instructors and students. Instructors will be able to fi nd teaching activities, chapter outlines, and chapters summaries. To aid students, the website contains a glossary, fl ashcards, crossword puzzles to help learn key terms, and web links to Wadsworth Online Research Methods workshops, as well as other useful web links; suggestions for using Infotrac College Edition; and multiplechoice, matching, fi ll-in-the-blank, and essay tutorial quizzes that can be printed out or emailed directly to instructors. Changes in the Ninth Edition Users of the previous edition will discover many changes in the current edition. Web references have been updated for all chapters; while these were working in January 2008, some will undoubtedly change during the life of this edition. These references guide readers to relevant discussions online, including the Wadsworth Online at The Wadsworth Psychology Study Center. In addition, instructors in North America who have specifi ed that InfoTrac College Edition be packaged with this text have been provided 4 months of free access to this extensive virtual library for their students. New coverage and more recent references have been added in every chapter, and some chapters have been rebuilt to refl ect the most recent fi ndings and topics, xxii PREFACE 59533_01_fm_pi-xxiv.indd xxii 9533_01_fm_pi-xxiv.indd xxii 3/6/08 7:06:51 PM /6/08 7:06:51 PM