Abstract: PrefaceNATURE OF THE BOOK This book attempts to collate and integrate thenfindings of published research, and some provocative conjecture,nregarding certain social and psychological effects of mass communicationMore specifically, the book is concerned with two major areasnof such effect Part I deals with mass communication as an agentnof persuasion and attempts to cite its known capabilities and limitationsnin that regard Part II deals with the effects of specific kindsnof media content which have been alleged to produce socially andnpsychologically important consequences An introductory chapter,nwhich is largely subjective, discusses the current state ofnknowledge of the effects of mass communication in general andnproposes a primitive theoretical scheme which is further discussed at various other explicitly labeled places in the book andnin the conclusion Except for the introduction and conclusion,nthe entire work is primarily a collection of the findings of othersThe book at times draws heavily upon an earlier work by thensame author (Klapper, 1949) The present volume, however, isnby no means a mere up-dating of the earlier one It differs from thenearlier work in its inclusion and discussion of the proposed theoreticalnscheme, in its far greater concern with extra-communicationnconditions which influence the effect of communications, and innthe areas of effect which are discussed Of the five topics discussednin the earlier volume, three have been retained and two of thesenare treated in much greater detail, and two have been omittednThree topics not treated in the earlier volume are here accordedna chapter eachLITERATURE SURVEYEDThe source material for this book consisted mainly of the vastnarray of learned and semi-leamed journals and of relevant booksnTraditional techniques of library research were employed in cullingnthis literature Journals of abstracts, bibliographies, and worksnknown to the author were used as starting points; the works citedncontained bibliographies and references which led to additionalnmaterial; and this snowballing was continued until the returnsnbecame so slight that it was clearly unprofitable to continueThis process led to the identification and investigation of overn1000 studies, essays, and reports More than 270 of these, which contributedndirectly to the present volume, are cited in the bibliographynThe others were found to be either wholly irrelevant tonthe topics of the book, to be so methodologically culpable as to benuseless, or, in some cases, to provide only one more confirmationnof some highly specific finding or point of view that had beennwidely confirmed or better expressed in other cited worksThe primary object of the literature search was to locate allnpublished reports of disciplined social research dealing with effectsno f mass communication in certain specific areas However, several unpublished works have found their way into the text and thenbibliography These include occasional doctoral dissertationsnwhich have attained some recognition outside the departments innwhich they were written, and several reports issued in unpublishednform by academic, commercial, and government agenciesnNo attempt has been made, however, exhaustively to explore suchnsources of unpublished material; the almost limitless volume, thenfrequently privileged status, and, above all, the sheer difficulty ofntracking down and obtaining these little-known works renderednany attempt at exhaustive examination beyond the budgetary andnphysical capabilities of the present study The value to the researchn fraternity of a central clearing house or information centernfor such materials has often been noted; unless and until the conceptnis somehow implemented, knowledge of the materials, andnthus their potential usefulness, will remain severely limitednIt must also be noted that a considerable number of the citednworks are not reports of research at all, but rather present thenconsidered conjecture of reputable and acute thinkers In addition,narticles from popular sources (eg, Parents Magazine) arenoccasionally cited as evidence of popular concern about particularneffects of the mediaFinally, and perhaps most importantly, a considerable numbernof the cited research studies do not deal with mass communicationsnper se, but with laboratory approximations thereof or with somenform of interpersonal communication; they have been included asnsource material because their findings appear to be at least hypotheticallynapplicable to mass communication as welln n n n n n