The Transmission Model of Communication
Here I will outline and critique a particular, very well-known model of communication developed by Shannon and Weaver (1949), as the prototypical example of a transmissive model of communication: a model which reduces communication to a process of ‘transmitting information’. The underlying metaphor of communication as transmission underlies ‘commonsense’ everyday usage but is in many ways misleading and repays critical attention.
Shannon and Weaver’s model is one which is, in John Fiske’s words, ‘widely accepted as one of the main seeds out of which Communication Studies has grown’ (Fiske 1982: 6). Claude Shannon and Warren Weaver were not social scientists but engineers working for Bell Telephone Labs in the United States. Their goal was to ensure the maximum efficiency of telephone cables and radio waves. They developed a model of communication which was intended to assist in developing a mathematical theory of communication. Shannon and Weaver’s work proved valuable for communication engineers in dealing with such issues as the capacity of various communication channels in ‘bits per second’. It contributed to computer science. It led to very useful work on redundancy in language. And in making ‘information’ ‘measurable’ it gave birth to the mathematical study of ‘information theory’. However, these directions are not our concern here. The problem is that some commentators have claimed that Shannon and Weaver’s model has a much wider application to human communication than a purely technical one.
C & W’s original model consisted of five elements:
An information source, which produces a message.
A transmitter, which encodes the message into signals
A channel, to which signals are adapted for transmission
A receiver, which ‘decodes’ (reconstructs) the message from the signal.
A destination, where the message arrives.
A sixth element, noise is a dysfunctional factor: any interference with the message travelling along the channel (such as ‘static’ on the telephone or radio) which may lead to the signal received being different from that sent.
For the telephone the channel is a wire, the signal is an electrical current in it, and the transmitter and receiver are the telephone handsets. Noise would include crackling from the wire. In conversation, my mouth is the transmitter, the signal is the sound waves, and your ear is the receiver. Noise would include any distraction you might experience as I speak.
Although in Shannon and Weaver’s model a speaker and a listener would strictly be the source and the destination rather than the transmitter and the receiver, in discussions of the model the participants are commonly humanised as the sender and the receiver. My critical comments will refer less specifically to Shannon and Weaver’s model than to the general transmission model which it reflects, where communication consists of a Sender passing a Message to a Receiver. So when I am discussing transmission models in general I too will refer to the participants as the Sender and the Receiver.
Shannon and Weaver’s transmission model is the best-known example of the ‘informational’ approach to communication. Although no serious communication theorist would still accept it, it has also been the most influential model of communication which has yet been developed, and it reflects a commonsense (if misleading) understanding of what communication is. Lasswell’s verbal version of this model: ‘Who says what in which channel to whom with what effect ?’ was reflected in subsequent research in human communication which was closely allied to behaviouristic approaches.
Levels of problems in the analysis of communication
Shannon and Weaver argued that there were three levels of problems of communication:
A The technical problem: how accurately can the message be transmitted?
B The semantic problem: how precisely is the meaning ‘conveyed’?
C The effectiveness problem: how effectively does the received meaning affect behaviour?
Shannon and Weaver somewhat naively assumed that sorting out Level A problems would lead to improvements at the other levels.
Although the concept of ‘noise’ does make some allowance for the way in which messages may be ‘distorted’, this frames the issue in terms of incidental ‘interference’ with the sender’s intentions rather than in terms of a central and purposive process of interpretation. The concept reflects Shannon and Weaver’s concern with accuracy and efficiency.
Advantages of Shannon and Weaver’s model
Particular models are useful for some purposes and less useful for others. Like any process of mediation a model foregrounds some features and backgrounds others. The strengths of Shannon and Weaver’s model are its
generality, and
Such advantages made this model attractive to several academic disciplines. It also drew serious academic attention to human communication and ‘information theory’, leading to further theory and research.
Weaknesses of the transmission model of communication
The transmission model is not merely a gross over-simplification but a dangerously misleading misrepresentation of the nature of human communication. This is particularly important since it underlies the ‘commonsense’ understanding of what communication is. Whilst such usage may be adequate for many everyday purposes, in the context of the study of media and communication the concept needs critical reframing.
Shannon and Weaver’s highly mechanistic model of communication can be seen as being based on a transport metaphor. James Carey (1989: 15) notes that in the nineteenth century the movement of information was seen as basically the same as the transport of goods or people, both being described as ‘communication’. Carey argues that ‘it is a view of communication that derives from one of the most ancient of human dreams: the desire to increase the speed and effect of messages as they travel in space’ (ibid.) Writing always had to be transported to the reader, so in written communication the transport of letters, books and newspapers supported the notion of the transport of meaning from writer to readers. As Carey notes, ‘The telegraph ended the identity but did not destroy the metaphor’ (ibid.).
Within the broad scope of transport I tend to see the model primarily as employing a postal metaphor. It is as if communication consists of a sender sending a packet of information to a receiver, whereas I would insist that communication is about meaning rather than information. One appalling consequence of the postal metaphor for communication is the current reference to ‘delivering the curriculum’ in schools, as a consequence of which teachers are treated as postal workers. But the influence of the transmission model is widespread in our daily speech when we talk of ‘conveying meaning’, ‘getting the idea across’, ‘transferring information’, and so on. We have to be very alert indeed to avoid falling into the clutches of such transmissive metaphors.
Michael Reddy (1979) has noted our extensive use in English of ‘the conduit metaphor’ in describing communicative acts. In this metaphor, ‘The speaker puts ideas (objects) into words (containers) and sends them (along a conduit) to a hearer who takes the idea/objects out of the word/containers’ (Lakoff & Johnson 1980: 10). The assumptions the metaphor involves are that:
Language functions like a conduit, transferring thoughts bodily from one person to another;
in writing and speaking, people insert their thoughts or feelings into the words;
words accomplish the transfer by containing the thoughts or feelings and conveying them to others;
in listening or reading, people extract the thoughts and feelings once again from the words. (Reddy 1979: 290)
As Reddy notes, if this view of language were correct, learning would be effortless and accurate. The problem with this view of language is that learning is seen as passive, with the learner simply ‘taking in’ information (Bowers 1988: 42). I prefer to suggest that there is no information in language, in books or in any medium per se. If language and books do ‘contain’ something, this is only words rather than information. Information and meaning arises only in the process of listeners, readers or viewers actively making sense of what they hear or see. Meaning is not ‘extracted’, but constructed.
In relation to mass communication rather than interpersonal communication, key metaphors associated with a transmission model are those of the hypodermic needle and of the bullet. In the context of mass communication such metaphors are now largely used only as the targets of criticism by researchers in the field.
The transmission model fixes and separates the roles of ‘sender’ and ‘receiver’. But communication between two people involves simultaneous ‘sending’ and ‘receiving’ (not only talking, but also ‘body language’ and so on). In Shannon and Weaver’s model the source is seen as the active decision-maker who determines the meaning of the message; the destination is the passive target.
It is a linear, one-way model, ascribing a secondary role to the ‘receiver’, who is seen as absorbing information. However, communication is not a one-way street. Even when we are simply listening to the radio, reading a book or watching TV we are far more interpretively active than we normally realize.
There was no provision in the original model for feedback (reaction from the receiver). Feedback enables speakers to adjust their performance to the needs and responses of their audience. A ‘feedback loop’ was added by later theorists, but the model remains linear.
Content and meaning
In this model, even the nature of the content seems irrelevant, whereas the subject, or the way in which the participants feel about it, can shape the process of communication. Insofar as content has any place (typically framed as ‘the message’), transmission models tend to equate content and meaning, whereas there may be varying degrees of divergence between the ‘intended meaning’ and the meanings generated by interpreters.
According to Erik Meeuwissen (e-mail 26/2/98) Shannon himself was well aware of the fact that his theory did not address meaning. He offers these supportive quotations from Shannon and Weaver:
The fundamental problem of communication is that of reproducing at one point either exactly or approximately a message selected at another point. Frequently the messages have meaning; that is they refer to or are correlated according to some system with certain physical or conceptual entities. These semantic aspects of communication are irrelevant to the engineering problem (Shannon 1948).
The word information, in this theory, is used in a special sense that must not be confused with its ordinary usage. In particular, information must not be confused with meaning. In fact, two messages, one of which is heavily loaded with meaning and the other of which is pure nonsense, can be exactly equivalent, from the present viewpoint, as regards information. It is this, undoubtedly, that Shannon means when he says that ‘the semantic aspects of communication are irrelevant to the engineering aspects. (Weaver 1949)
Weaver also noted that the theory
…has so penetratingly cleared the air that one is now, perhaps for the first time, ready for a real theory of meaning. An engineering communication theory is just like a very proper and discreet girl accepting your telegram. She pays no attention to the meaning whether it be sad, or joyous, or embarrassing. But she must be prepared to deal with all that come to her desk (Weaver 1949).
However, the important point here is that meaning-making is not central in transmission models. It is widely assumed that meaning is contained in the ‘message’ rather than in its interpretation. But there is no single, fixed meaning in any message. We bring varying attitudes, expectations and understandings to communicative situations. Even if the receiver sees or hears exactly the same message which the sender sent, the sense which the receiver makes of it may be quite different from the sender’s intention. The same ‘message’ may represent multiple meanings. The word ‘message’ is a sort of microcosm of the whole postal metaphor, so I’m not happy with even using that label.
Transmission models treat decoding as a mirror image of encoding, allowing no room for the receiver’s interpretative frames of reference. Where the message is recorded in some form ‘senders’ may well have little idea of who the ‘receivers’ may be (particularly, of course, in relation to mass communication). The receiver need not simply accept, but may alternatively ignore or oppose a message. We don’t all necessarily have to accept messages which suggest that a particular political programme is good for us.
The transmission model is an instrumental model in that it treats communication as a means to a predetermined end. Perhaps this is the way in which some people experience communication. However, not all communication is intentional: people unintentionally communicate a great deal about their attitudes simply through body language. And, although this idea will sound daft to those who’ve never experienced it, when some of us write something, we sometimes find out what we want to say only after we’ve finished writing about it.
Some critics argue that this model is geared towards improving a communicator’s ability to manipulate a receiver. Carey notes that ‘the centre of this idea of communication is the transmission of signals or messages over distance for the purposes of control… of distance and people’ (Carey 1989: 15).
In an instrumental framework the process involved is intended to be ‘transparent’ to the participants (nothing is intended to distract from the sender’s communicative goal). Such a conception is as fundamental to the rhetoric of science as it is alien to that of art. ‘Perfectly transparent communication’ is impossible.
Nor is there any mention in the transmission model of the importance of context: situational, social, institutional, political, cultural, historical. Meaning cannot be independent of such contexts. Whilst recorded texts (such as letters in relation to interpersonal communication and newspapers, films, radio and television programmes in relation to mass communication) allow texts to be physically separated from their contexts of production, this is not to say that meaning can be ‘context-free’. Whilst it is true that meaning is not wholly ‘determined’ by contexts of ‘production’ or ‘reception’ (texts do not mean simply what either their producers or their interpreters choose for them to mean), meanings may nevertheless be radically inflected by particular contexts of ‘writing’ and ‘reading’ in space and time. The ‘same’ text can be interpreted quite differently within different contexts.
Social contexts have a key influence on what are perceived as appropriate forms, styles and contents. Regarding situational context, it makes a lot of difference if the sender is an opinionated taxi-driver who drives aggressively, and the receiver is a passenger in the back seat whose primary concern is to arrive at the destination in one piece.
Relationships and purposes
In the transmission model the participants are treated as isolated individuals. Contemporary communication theorists treat communication as a shared social system. We are all social beings, and our communicative acts cannot be said to represent the expression of purely individual thoughts and feelings. Such thoughts and feelings are socio-culturally patterned. Even what we call ‘our’ language isn’t our own: we are born into it; we can’t change the rules. Words have connotations which we don’t choose for them. An emphasis on creative individuality is itself a culturally-shaped myth which had a historically ‘modern’ origin in Western Europe.
Transmission models of communication reduce human communication to the transmission of messages, whereas, as the linguists tell us, there is more to communication than this. They refer, for instance, to phatic communication, which is a way of maintaining relationships. In Britain, talking about the weather is far more a matter of phatic communication than of ‘transmitting information’.
No allowance is made in the transmission model for differing purposes. The same TV images of a football match would have very different meanings for the fans of opposing sides.
In models such as Shannon and Weaver’s no allowance is made for relationships between people as communicators (e.g. differences in power). We frame what is said differently according to the roles in which we communicate. If a friend asks you later what you thought of this lecture you are likely to answer in a somewhat different way from the way you might answer the same question from the undergraduate course director in his office. The interview is a very good example of the unequal power relationship in a communicative situation.
People in society do not all have the same social roles or the same rights. And not all meanings are accorded equal value. It makes a difference whether the participants are of the same social class, gender, broad age group or profession. We need only think of whose meanings prevail in the doctor’s surgery. And, more broadly, we all know that certain voices ‘carry more authority’ than others, and that in some contexts, ‘children are to be seen and not heard’. The dominant directionality involved in communication cannot be fixed in a model but must be related to the situational distribution of power.
Furthermore, Shannon and Weaver’s model makes no allowance for dynamic change over time. People don’t remain frozen in the same roles and relationships, with the same purposes. Even within the course of a single conversation, such relationships may continuously shift. Also, adopting a more ‘historical’ perspective, however stable the text may seem to be, the ways in which a recorded text may be interpreted depends also on circumstances at that time of its interpretation.
Finally, the model is indifferent to the nature of the medium. And yet whether you speak directly to, write to, or phone a lover, for instance, can have major implications for the meaning of your communication. There are widespread social conventions about the use of one medium rather than another for specific purposes. People also differ in their personal attitudes to the use of particular media (e.g. word processed Christmas circulars from friends!).
Furthermore, each medium has technological features which make it easier to use for some purposes than for others. Some media lend themselves to direct feedback more than others. The medium can affect both the form and the content of a message. The medium is therefore not simply ‘neutral ‘ in the process of communication.
In short, the transmissive model is of little direct value to social science research into human communication, and its endurance in popular discussion is a real liability. Its reductive influence has implications not only for the commonsense understanding of communication in general, but also for specific forms of communication such as speaking and listening, writing and reading, watching television and so on. In education, it represents a similarly transmissive model of teaching and learning. And in perception in general, it reflects the naive ‘realist’ notion that meanings exist in the world awaiting only decoding by the passive spectator. In all these contexts, such a model underestimates the creativity of the act of interpretation.
Alternatives to transmissive models of communication are normally described as constructivist: such perspectives acknowledge that meanings are actively constructed by both initiators and interpreters rather than simply ‘transmitted’. However, you will find no single, widely-accepted constructivist model of communication in a form like that of Shannon and Weaver’s block diagram. This is partly because those who approach communication from the constructivist perspective often reject the very idea of attempting to produce a formal model of communication. Where such models are offered, they stress the centrality of the act of making meaning and the importance of the socio-cultural context.
Bowers, C. A. (1988): The Cultural Dimensions of Educational Computing: Understanding the Non-Neutrality of Technology. New York: Teachers College Press [generally very useful, though difficult, and cited here only for commentary on Michael Reddy on pages 42-4]
Carey, James (1989): Communication as Culture. New York: Routledge (Chapter 1, ‘A Cultural Approach to Communication’)
Ellis, Russell & Ann McClintock (1990): If You Take My Meaning: Theory into Practice in Human Communication. London: Arnold (Chapter 5, (Communication Models’)
Fiske, John (1982): Introduction to Communication Studies. London: Routledge (Chapter 1, ‘Communication Theory’ is a good introduction to this topic)
Kress, Gunther (1988): ‘Communication and Culture’. In Gunther Kress (Ed.): Communication and Culture. Kensington, NSW: New South Wales University Press
Lakoff, George & Mark Johnson (1980): Metaphors We Live By. Chicago: University of Chicago Press
McQuail, Denis & Sven Windahl (1993): Communication Models for the Study of Mass Communication. London: Longman
Reddy, Michael J. (1979): ‘The Conduit Metaphor: A Case of Frame Conflict in our Language about Language’. In Andrew Ortony (Ed.): Metaphor and Thought. Cambridge: Cambridge University Press [for commentaries see: Bowers 1988: 38ff; Lakoff & Johnson 1980: 10-12]
Shannon, Claude E (1948): ‘A Mathematical Theory of Communication’, Part I, Bell Systems Technical Journal, 27, pp. 379-423
Shannon, Claude E. & Warren Weaver (1949): A Mathematical Model of Communication. Urbana, IL: University of Illinois Press
Smith, Frank (1983): Essays into Literacy. Portsmouth: Heinemann (Chapter 13, ‘A Metaphor for Literacy – Creating Worlds or Shunting Information?’)
Thwaites, Tony, Lloyd Davis & Warwick Mules (1994): Tools for Cultural Studies: An Introduction. South Melbourne: Macmillan (Chapter 1)
Weaver, Warren (1949): ‘Recent Contributions to the Mathematical Theory of Communication’. In Shannon & Weaver op.cit
See also any general reference books on communication.
Daniel Chandler
UWA 1994
I’d like to thank Erik Meeuwissen for leaping to the defence of Shannon and Weaver.
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