1. The Transmission Model of Communication
Daniel Chandler
Introduction
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.

2. C & W's original model consisted of five elements:
1. An information source, which produces a message.
2. A transmitter, which encodes the message into signals
3. A channel, to which signals are adapted for transmission
4. A receiver, which 'decodes' (reconstructs) the message from the signal.
5. 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:

3. o A The technical problem: how accurately can the message be
transmitted?
o B The semantic problem: how precisely is the meaning 'conveyed'?
o 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
o simplicity,
o generality, and
o quantifiability.
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.

4. Metaphors
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:
o Language functions like a conduit, transferring thoughts bodily from one
person to another;
o in writing and speaking, people insert their thoughts or feelings into the
words;
o words accomplish the transfer by containing the thoughts or feelings and
conveying them to others;
o in listening or reading, people extract the thoughts and feelings once
again from the words. (Reddy 1979: 290)

5. 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.
Linearity
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.

6. 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

7. 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.
Instrumentalism
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.
Context
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.

8. Social contexts have a key influence on what are perceived as appropriate
forms, styles and contents. Regardingsituational 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

9. 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.
Time
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.
Medium
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.
Conclusion
In short, the transmissive model is of little direct value to social science
research into human communication, and its endurance in popular discussion is

10. 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.
References
o 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]
o Carey, James (1989): Communication as Culture. New York: Routledge
(Chapter 1, 'A Cultural Approach to Communication')
o Ellis, Russell & Ann McClintock (1990): If You Take My Meaning:
Theory into Practice in Human Communication. London: Arnold
(Chapter 5, (Communication Models')
o Fiske, John (1982): Introduction to Communication Studies. London:
Routledge (Chapter 1, 'Communication Theory' is a good introduction to
this topic)
o Kress, Gunther (1988): 'Communication and Culture'. In Gunther Kress
(Ed.): Communication and Culture.Kensington, NSW: New South Wales
University Press
o Lakoff, George & Mark Johnson (1980): Metaphors We Live
By. Chicago: University of Chicago Press

11. o McQuail, Denis & Sven Windahl (1993): Communication Models for the
Study of Mass Communication. London: Longman
o 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]
o Shannon, Claude E (1948): 'A Mathematical Theory of Communication', Part
I, Bell Systems Technical Journal, 27, pp. 379-423
o Shannon, Claude E. & Warren Weaver (1949): A Mathematical Model of
Communication. Urbana, IL: University of Illinois Press
o Smith, Frank (1983): Essays into Literacy. Portsmouth: Heinemann
(Chapter 13, 'A Metaphor for Literacy - Creating Worlds or Shunting
Information?')
o Thwaites, Tony, Lloyd Davis & Warwick Mules (1994): Tools for
Cultural Studies: An Introduction. South Melbourne: Macmillan
(Chapter 1)
o 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