On the Vitality of our Discipline- New Applications of Communications Theory: The 1990 Southam Lecture

William Leiss (Simon Fraser University)


With these meetings the Association starts the second decade of its existence. Events during the intervening period appear to confirm the belief, held by the Association's founding members, that the field of communication studies is a dynamic academic discipline whose importance will continue to grow both in Canada and Quebec. At many universities there has been a steady increase in undergraduate enrollments, high-quality graduate programs, and permanent faculty positions; and there also have been major innovations in the field, such as the multi-university doctoral program in Montreal.

These professional developments are occurring for us at a time when political events around the world are demonstrating once again the centrality of communicative processes in social life. In Europe and elsewhere the mask of legitimacy has been torn from many long-standing political structures, along with the nation-state entities that gave them legal force, all of which have proved to be artificial and obsolete and are crumbling. Social groupings based on what appear to be more solid foundations--a collective identity that is defined most sharply by language and an associated cultural tradition--are reasserting themselves against the artificial political structures into which they had been submerged. Above all what has been revealed in this process is how fraudulent were the superficial tokens of public allegiance offered in the past to those now-discredited political regimes: For those tokens had been extracted in some cases by simple terror; in others, by promises of a rosy future that itself had turned out to be just a massive fraud perpetrated by corrupt elites; in still others, by a fear that the standard of living and economic prosperity citizens were accustomed to would be jeopardized if they were to vote to change the existing political order.

To the extent to which these recent developments represent an authentic expression of the popular will, against the inauthentic public manifestations of the past, they are an immensely hopeful sign. To be sure, there are other forces at work as well, especially the global integration of economic and technological change, which will require new political associations, different from the discredited or obsolete ones, to bind together the linguistically-defined communities. And, of course, there are regressive features as well which must be combatted, especially the immediate outbreaks of intolerance and hatred among groups with long traditions of ethnic rivalry or the ancient European scourge of anti-Semitism.

Given the nature of these developments, I believe, specialists within the discipline of communication studies may be expected to contribute to understanding them and to resolving the new social problems that have arisen in their wake. I claim no special expertise in these matters and have made these preliminary remarks just to introduce my theme. What I want to do today is to refer back to an old paradigm in communications theory, and to show how an awareness of the unique features of communications processes has been helping to form an effective approach to a major public policy issue in North America. The results illustrate for me the vitality of our discipline in the contemporary period.

The Message Transmission Theory

What I have chosen to call the "message transmission theory" has its origins in the famous Lasswell definition of the act of communication (1948):2

A convenient way to describe an act of communication is to answer the following questions:

  • Who
  • Says What
  • In Which Channel
  • To Whom
  • With What Effect?

The scientific study of the process of communication tends to concentrate upon one or another of these questions. Scholars who study the "who," the communicator, look into the factors that initiate and guide the act of communication. We call this subdivision of the field of research control analysis. Specialists who focus upon the "says what" engage in content analysis. Those who look primarily at the radio, press, film and other channels of communication are doing media analysis. When the principal concern is with the persons reached by the media, we speak of audience analysis. If the question is the impact upon audiences, the problem is effect analysis.

Like other aspects of the study of communication in the immediately preceding period, this definition arose out of the concern with the nature and effects of propaganda.3

An early variant on this theme, and the first account (so far as I know) which gave a diagrammatic representation for the message transmission theory, appeared a year later in Claude Shannon and Warren Weaver's The Mathematical Theory of Communication. (See Figure 1.) This version was oriented towards the engineering aspects of communication--in fact, it was Weaver's discursive interpretation of Shannon's mathematical theory--and so it incorporates the additional elements of signal and noise, as well as transmitting and receiving devices. In addition, it conceives of the channel as either a technological or natural medium: a wire in the case of telephony, "space" in the case of radio; due to the special characteristics of the medium, there is a new element (a coding and decoding process) when the transmitter/receiver turns a message into a signal and vice versa. For Weaver, the theory is applicable to the familiar situation of human face-to-face communication, as well as to all forms of technologically-mediated communication: "When I talk to you, my brain is the information source, yours the destination; my vocal system is the transmitter, and your ear and associated eighth nerve is the receiver."4 Figure 1 The Engineering Theory of Communication

Shannon & Weaver (1949).

Later Weaver extends the engineering analogy further by suggesting that another box, the "semantic receiver," could be added to the diagram between the engineering receiver and the destination, which "subjects the message to a second decoding, the demand on this one being that it must match the statistical semantic characteristics of the message to the statistical semantic capacities of the totality of receivers, or of that subset of receivers which constitute the audience one wishes to affect." Curiously, Weaver did not think of a complementary "semantic transmitter," i.e., a second level of encoding interposed between the information source and the engineering transmitter--probably because the elaborate effort of "repackaging" information, for example in marketing and advertising, was not well understood at the time. But Weaver does mention "semantic noise," as an adjunct to engineering noise:5

From this source is imposed into the signal the perturbations or distortions of meaning which are not intended by the source but which inescapably affect the destination. And the problem of semantic decoding must take this semantic noise into account. It is also possible to think of an adjustment of original message so that the sum of message meaning plus semantic noise is equal to the desired total message meaning at the destination.

If Weaver could have conceived of the channel in institutional rather than purely technological terms, he would have realized that in "semantic noise" he had a good concept of the independent effect of channel organization on the nature and presentation of messages. In any case, Figure 2 shows what Weaver's complete version of the message transmission theory would look like if these additions were to be made. Figure 2 The Engineering Theory (Complete)

Adapted from Shannon & Weaver (1949).

All theories have inherent limitations on their applicability, and the message transmission theory is no exception. The hidden feature of Lasswell's original conception is that it pretends to be a full and complete representation of the act of communication per se--that is, of all possible expressions of communicative processes. This is inappropriate. A proviso is required, and indeed is indicated in the name which I have bestowed upon it: The Lasswell definition describes well the elements of the communications act considered as a process for the transmission of messages, especially when they are mediated via a technological channel--as a theory of mediated communication. When we recognize this limitation, however, we can also acknowledge the theory's power and range.6

An indicator of just how great that power and range is can be found in a review-article published five years ago. W. J. McGuire published a review of the literature on persuasive communication as a part of the larger topic of attitudes and attitude change.7 McGuire organized his discussion within the framework of what I have called the message transmission theory, and which he labels "an input/output analysis of the communication/persuasion process" (see Figure 3). The inputs in this matrix are the components of the message system itself (source, message, channel, receiver, target); and the output side is described by McGuire as a succession of "response steps that the receivers must be induced to take if the communication is to have its intended persuasive impact." His discussion of the relevant published literature occupies no less than 35 pages of single-spaced, double-column text and demonstrates that each of the points of intersection in the matrix has been the subject of many separate studies. leisfig3

My colleagues and I did not refer explicitly to the message transmission theory in our study of advertising (1986), but we might very well have done so, since our treatment of the subject fits nicely into this framework. This is because we approach advertising as both a powerful mode of persuasive communication and as a form of mediated communication--indeed, one which incorporates a threefold process of mediation.8 As Figure 4 shows, one type of mediation occurs between producers and consumers, wherein ad agencies assist producers in encoding products with symbolic meanings; another, between producers and the media, wherein agencies assist producers in choosing the right "media mix" (and the media content--advertising content relation) for attaining the strategic objectives of their marketing campaigns; and a third, between media and their audiences, wherein agencies assist both producers and the media in understanding the decoding processes of audiences. Figure 4 Advertising as Persuasive Communication Process and the Role of Ad Agencies in this Process

  • First Mediation ("Encoding Noise"): Producers/Agencies/Consumers
    (Consumer Behaviour Research)
  • Second Mediation ("Channel Noise"): Producers/Agencies/Media
    (Media Consumption Research)
  • Third Mediation ("Decoding Noise"): Media/Agencies/Audiences
    (Audience Research)
Adapted from Leiss, Kline, & Jhally (1990).

Our study of advertising shows that the message transmission theory is capable of accommodating an approach that gives full recognition to social institutions and their operative capacities. Seen within the framework of a detailed institutional analysis, relations of power and control, manipulation, equity, and so forth are shown to be represented concretely in both what is present and what is absent in message content (in the form of selectivity, bias, stereotyping, dominant values, etc.). Thus one can "overlay" the institutional analysis on the message transmission model: Combining the complete version of Weaver's engineering model (Figure 2) with the threefold structure of mediation in advertising (Figure 4) yields the result shown in Figure 5, which demonstrates how the message transmission theory is capable of being infused, in a structured way, with the "real," historical content that exists in the development of modern social institutions. Figure 5 An Institutional Version of the Engineering Theory: The Case of Advertising

But this is not the example I wish to focus on today, however, in illustrating the vitality of our discipline that is expressed in the new applications of communications theory. Rather, I want to do this by examining the relatively unfamiliar domain which goes by the name of "risk communication." What I intend to show is that a model of communications processes was required in order to make a significant advance in our approach to a very important aspect of public policy in all advanced industrial societies today. In this example, too, we will discover that the message transmission theory is capable of representing in a dynamic way a set of contents and relations that have developed in the play of institutional forces in contemporary society.

Risk Communication

Risk communication has been defined as "any purposeful exchange of information about health or environmental risks between interested parties."9 Almost everyone is now aware that both natural processes, industrial technologies, and consumer preferences give rise to hazards which threaten human health, nonhuman species, and the functioning of planetary ecosystems upon which the former depend. (An earthquake is an example of a natural hazard; acid rain is a type of ecosystem hazard arising from industrial technology; and cigarette smoking is a kind of voluntary consumer choice which exposes individuals to a wide range of specific health hazards.) The chances that any individual or group will suffer adverse consequences of varying severity stemming from exposure to such hazards can be expressed as a measure of the risk we incur in particular situations.10 Popular demands for better protecting human health and the environment from the impacts of industrial technologies are now a major determinant of public policy in many nations.

The phrase "risk communication" originated in English usage only about five years ago; it has attained wide recognition in a specialized literature since that time, and is slowly appearing in other European languages, such as German.11 Over the period of its development there has been a shift in emphasis from the adjective to the noun in this phrase. As it was first conceived, the chief task of risk communication was thought to be learning how to convey, to the relatively unsophisticated members of "the public," the pure, rational knowledge content inherent in the assessment of risks made by scientific and engineering "experts."12 In this phase the chief obstacle to meaningful risk communication was thought to be the public's inability or unwillingness to grasp the nature and implications of the concept of risk itself and, flowing from this, the public's unrealistic demands for protection from certain types of hazards.

Thus the emphasis was on technically-assessed risk itself; the presumption was that, once the rational content of technical risk was conveyed more effectively, the "irrational" resistance of publics to the calculations of acceptable risk which were derived from technical risk assessments would evaporate. An example that appeared frequently in the literature was that of nuclear power: Whereas most "energy experts" think that the risks attendant upon nuclear energy generation are relatively low, in comparison with many other risks in contemporary society, most members of "the public" see the matter quite differently, ranking these risks well above most others with which they are familiar. Many experts regard the public view in this case as highly irrational and wrongheaded, and they believe that this view results in incorrect public policy choices--for example, leading to preferences for other types of energy generation which have greater adverse environmental impacts. Such disagreements about the assessment of risk occur in virtually every aspect of our uses of technological innovations: chemicals in agriculture and every type of industry; transportation of hazardous goods; food additives; the siting of waste treatment facilities; energy production and distribution; forest practices; and many others.

It is necessary for us to appreciate just how large are the stakes for society as a whole in this type of controversy. Among other things, what is at stake is the ability of citizens to have substantive input into the decisions that affect their lives. In addition, there are huge costs involved in providing adequate remedies for polluted environments and in protecting us from exposure to various types of hazards: We need to know urgently whether our priorities for environmental protection policies, and for the allocation of public and private-sector resources to pay the costs of the actions we believe should be undertaken, are based on the best information and reasoning on these matters. For if we make serious mistakes in this regard, the risk we run is that we will have wasted considerable sums of money--money which might have been spent in other ways to control the effects of serious hazards.

But a discussion about risks that was structured as lectures by experts to the public soon showed itself to be a counter-productive exercise. There was massive distrust on both sides: The public saw experts as using the language of risk as a cover for letting industry have a free hand with project developments, and the experts saw many members of the public as using an ignorance of risk assessment as a way of opposing everything that appeared to change established routines of life. Governments, caught in the middle, were unable to facilitate solutions to this impasse.

It was at this point that risk practitioners in the United States, led by Vincent Covello, began to champion a radically different approach to public debates on risk management. They did so by re-framing the issue of risk communication as a problem in communicative theory and practice, rather than in the concept of risk. In other words, they shifted the emphasis from the adjective to the noun in this phrase. Moreover, they chose the message transmission model as a specific way of representing the many problems that had been encountered in the earlier approach: These were now labelled source problems, message problems, channel problems, and receiver problems.13 These problems may be mapped onto the simplified version of the engineering theory as shown in Figure 6. Figure 6 Risk Communication Problems

Adapted from Shannon & Weaver (1949).

Source Problems in risk communication include disagreements among experts (resulting in different messages about the same set of conditions); lack of understanding of and information on the concerns, confusions, and values of those members of the public who are most directly affected by specific proposals (for example, the communities in the immediate vicinity of plant sitings); and lack of public credibility for experts attached to certain institutions, such as corporations or governments, when those institutions are perceived as being proponents for industrial developments that are likely to generate incremental risks. Thus "source problems" are doubts about the accuracy, truthfulness, or completeness of the message which arise from doubts about the impartiality or competence or thoroughness of the experts who are assessing risks.

Message Problems most often result from inadequacies in the established scientific databases relevant to proposed developments (so that key information is not available when decisions are taken); from the irreducible uncertainties that are necessarily a part of the statements of risk in scientific terms (which are always expressed as probabilities); and from the inherent complexities in the concept of risk itself. These types of message problems create difficulties even when there is a predisposition on the part of an agency to do the best possible job in communicating about risk with the public.

For risk experts, Channel Problems are almost always thought of in terms of the inadequacies of the mass media in reporting "objectively" about health and environmental hazards.14 Bias, sensationalism, and oversimplification are charges laid at the media's door by those who think that both electronic and print journalists do a poor job of reporting about risks. Journalists respond that risk experts often do not willingly tell the whole story, that they sometimes conceal material facts or even disseminate falsehoods, that they do not express themselves clearly, and in general are patronizing in their relations with the public and the press.

Finally, Receiver Problems have to do with the ways in which non-expert members of the public assimilate and react to risk situations of all kinds; research in the field of risk perception has been extremely valuable in clarifying this issue. People respond in varied ways to probabilistic situations in everyday life, for example in gambling, and their responses are relevant to the area of technological hazards as well. Many people are overconfident in areas familiar to them, such as driving, and at the same time can be very fearful of risks where they are unfamiliar with the technologies involved. These and many other factors turn out to be decisive elements in how members of the public react to the scientific assessment of risks.15

This reconceptualization of the problem of risk communication enabled its proponents to break down what appeared to be a single, large, and intractable problem (as initially expressed: how scientists could get the public to understand the expert conception of risk) into a structured set of much smaller and potentially manageable issues. The process of reconceptualization was the adaptation of the message transmission theory, as a model of the persuasive communications approach, to the problem of forming social consensus about environmental risk. The "solution" to the difficulties experienced in the earlier approach to risk communication was to put the emphasis on communications processes themselves.

In an earlier paper Dan Krewski and I presented a general conception of risk communication as it appears from the perspective of communications processes (see Figure 7).16 What is implied here is that information exchanges about risks occurring in a public policy context are likely to be expressed either in the "language" of technical risk (in scientific, engineering, or mathematical terms) or in the language of ordinary, everyday speech; thus communication flows occur in either direction between those speaking one of these languages. In addition, there is a significant amount of information flow within and among specific institutional actors (represented by the two circular arrows in the diagram) that is expressed in one of the two languages. Figure 7 The Communications Processes Model of Risk Communication

Leiss & Krewski (1989).

This is a refinement of the application of the message transmission theory to the risk area; problems of the kind listed above (source, message, channel and receiver) are encountered when specific instances of risk communication flows are analyzed within the context of institutional forces.

A Special Case: Health Hazard Warnings

Hazard warnings may be regarded as an applied form of risk communication. Adequate measures for alerting the public to the existence and nature of environmental and health hazards result in many benefits to society. For example, if hazard information is effective, then individuals can be allowed to make their own informed choices over the widest possible range of opportunities, thus increasing their freedom of action. Also, anything that reduces or prevents exposure to hazardous materials or activities also reduces society's health care costs, and enhances the quality of life for those who would otherwise have been injured or killed. The purpose of warnings is to communicate effectively to the public the risks associated with the use or misuse of a product, device, facility, or type of activity.

By communicating those risks, product manufacturers, government regulators, or facility operators seek to both (a) inform users about the circumstances under which their health and safety might be jeopardized, and (b) advise them as to what actions they can take to reduce their risk. For example, a major effort is under way in Canada at the present time to increase the effectiveness of the hazard warnings that are required on tobacco product packages, by changing the major design parameters (placement on package, colour contrast, size of warning panel) as well as the wording of the warning texts (the most dramatic of the proposed new warnings is "Smoking is Addictive").17 Since tobacco use is, among all "voluntary" activities, the single greatest source of adverse health impacts in Canadian society, there is a great deal at stake in this exercise in applied risk communication.

In an influential article published ten years ago, W. J. McGuire applied the persuasive communications model (what I have called the message transmission theory) to the field of hazard warnings.18 Experts in the latter field then used this approach to organize the substantial body of knowledge that has accumulated in all aspects of the design, implementation, and evaluation of effectiveness of health hazard warnings. The message transmission theory turned out to be the most useful model for identifying the nature and interrelations of the structural components in the hazard warning process.19

Finally, one can see also in a related field of applied communication (which is also very important in contemporary society)--namely, health promotion strategies--that the message transmission theory has been helpful as an analytical tool.20


In this paper I have tried to show how a model developed long ago in communications theory has been applied recently in a number of very important arenas of contemporary public policy debate. How to deal with health and environmental protection is one of the most difficult and challenging public policy issues of our time, and one key aspect of that issue is the public understanding of risk assessment and risk management, and the public acceptance of the place of scientific and technical knowledge in the making of decisions about risks.

What is evident in the development of this issue is that the policy debates, and indeed some regulatory action on risks, had reached an impasse, due to public distrust of the form of risk communication where experts preached to the public about the authoritative way in which risk must be evaluated. This impasse was broken with the recognition that the problem at hand was fundamentally a matter of communicative processes. The adoption of the persuasive communications model certainly did not provide a magical solution to problems in risk communication, but in my view it did supply the necessary preconditions for arriving at those solutions. In so doing it demonstrated the vitality of our discipline and the contributions it can make to progressive steps in social policy.


I wish to thank Professor David Crowley of McGill University for assisting in uncovering the origins of the message transmission theory.
Harold D. Lasswell. (1964). The structure and function of communication in society. In L. Bryson (Ed.). The communication of ideas (p. 37). New York: Cooper Square Publishers, 1964). This volume was first published in 1948.
B. L. Smith, H. D. Lasswell, & R. D. Casey. (1946). Propaganda, communication, and public opinion. Princeton: Princeton University Press.
Claude E. Shannon & Warren Weaver. (1949). The mathematical Theory of Communication (pp. 7-8). Urbana, Ill.: University of Illinois Press. I was introduced to this unusual work by Dallas Smythe, when we were both in Regina, more than 20 years ago.
Ibid., p. 26.
It seems to me that this power and range is seriously underestimated in the influential text by M. L. DeFleur & S. Ball-Rokeach. (1989). Theories of mass Communication (5th ed., pp. 189-190). New York and London: Longman.
William J. McGuire. (1985). Attitudes and attitude change. In G. Lindzey & E. Aronson (Eds.). Handbook of social psychology (Vol. 2, 3rd ed., pp. 233-346). New York: Random House, 1985). The discussion of persuasive communication is in pp. 258-94. Figure 3 is McGuire's Table 1, p. 259, with some additions drawn from his succeeding discussion.
W. Leiss, S. Kline, & S. Jhally. (1990). Social communication in Advertising (2nd ed., Figure 7.2 and pp. 191-193). Toronto: Nelson.
V. Covello, D. von Winterfeldt, & P. Slovic. (1986). Risk communication: A review of the literature. Risk Abstracts, 3, 172.
W. Leiss. (1990). Risks: Managing the consequences of innovation. In L. Salter & D. Wolfe (Eds.). Managing technology. Toronto: Garamond.
The earliest reference in Covello's review article (see note 8) is dated 1984. For Germany, see H. Jungermann, R. E. Kasperson, & P. M. Wiedemann (Eds.). (1988). Themes and tasks of risk communication. Kernforschungsanlage Julich.
See generally B. Fischoff, P. Slovic, & S. Lichtenstein. (1983). "The public" vs. "the experts": Perceived vs. actual disagreements about risks. In V. Covello et al. (Eds.). The analysis of actual versus perceived risks (pp. 235-249). New York: Plenum Press.
V. Covello, D. von Winterfeldt, & P. Slovic. (1987). Communicating scientific information about health and environmental risks. In J. C. Davies, V. T. Covello, & F. W. Allen (Eds.). Risk communication (pp. 110-112). Washington, D.C.: The Conservation Foundation.
For a review of this literature, see Richard Smith. (1990, March). Risk communication and the media: An annotated bibliography. In L. Craig (Ed.). Issues and challenges in risk communication and the mass media (IRR Paper No. 17). Institute for Risk Research, University of Waterloo.
The best introduction to this subject is the report prepared by D. Wehrung and I. Vertinsky from the "Workshop on Risk Perception and Drug Safety Evaluation" (Ottawa: Drugs Directorate, Health Protection Branch, Health and Welfare Canada, March 1990). Figure 3 in this report provides a nice overview of how the many components of risk perception may be integrated with risk communication practices.
W. Leiss & D. Krewski. (1989). Risk communication: Theory and practice. In W. Leiss (Ed.). Prospects and problems in risk communication (pp. 99-102). Waterloo, Ont.: University of Waterloo Press.
Health Protection Branch, Health and Welfare Canada. (1990, March 1). Proposed amendments to the tobacco products control regulations. Information Letter No. 776. Ottawa.
W. J. McGuire. (1980). The communication-persuasion model and health-risk labeling. In L. A. Morris et al. (Eds.). Product labeling and health risks (pp. 99-122). Banbury Report No. 6. Cold Spring Harbor Laboratory.
M. R. Lehto & J. M. Miller. Warnings, Vol. 1. Fundamentals, design, and evaluation methodologies. Ann Arbor, Mich.: Fuller Technical Publications. See p. 18 and Figure 2-2.
Donna Phillips (University of Calgary). (1990, June). Health promotion theories, strategies and models: Application to nutrition education. Paper delivered at the CCA/ACC Meetings, Victoria, B.C.

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