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Shannon weaver model of communication?

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2012-05-14 19:34:52

The Shannon-Weaver Model (1949)

The Shannon-Weaver model is typical of what are often referred

to as transmission models of communication. For criticisms of such

models, you should consult the section on criticisms of

transmission models. If you have looked through the examples of

typical everyday forms of communication, you will have noticed that

some of the examples refer to less immediate methods of

communication than face-to-face interaction, e.g. using the radio,

newspapers or the telephone. In these cases, technology is

introduced. When, for instance, the telephone is used, you speak,

the phone turns the sound waves into electrical impulses and those

electrical impulses are turned back into sound waves by the phone

at the other end of the line. Shannon and Weaver's mathematical

model of communication is widely accepted as one of the main seeds

out of which communication studies have grown. Their work developed

during the Second World War in the Bell Telephone laboratories in

the US; their main concern was to work out a way in which the

channels of communication could be used most efficiently.

Claude Shannon and Warren Weaver produced a general model of


This is now known after them as the Shannon-Weaver Model.

Although they were principally concerned with communication

technology, their model has become one, which is frequently

introduced to students of human communication early in their study.

However, despite the fact that it is frequently used early in the

study of human communication, I think it's worth bearing in mind

that information theory, or statistical communication theory was

initially developed to separate noise from information-carrying

signals. That involved breaking down an information system into

sub-systems so as to evaluate the efficiency of various

communication channels and codes. You might ask yourself how viable

the transfer of Shannon's insights from information theory to human

communication is likely to be. The concepts of information theory

and cybernetics are essentially mathematical and are intended to be

applied to technical problems under clearly defined conditions.

After you've read this section, which, I think, is a reasonable

attempt to loosely apply Shannon's ideas to human communication,

ask yourself whether you feel enlightened.

The Shannon-Weaver Model (1947) proposes that all communication

must include six

elements: • a source

an encoder

a message

a channel

a decoder

a receiver

These six elements are shown graphically in the model. As

Shannon was researching in the field of information theory, his

model was initially very technology-oriented. The model was

produced in 1949, a year after Lasswell's and you will immediately

see the similarity to the Lasswell Formula.

The emphasis here is very much on the transmission and reception

of information. 'Information' is understood rather differently from

the way you and I would normally use the term, as well. This model

is often referred to as an 'information model' of communication.

(But you don't need to worry about that if you're just


Apart from its obvious technological bias, a drawback from our

point of view is the model's obvious linearity. It looks at

communication as a one-way process. That is remedied by the

addition of the feedback loop, which you can see in the developed

version of the model:

A further drawback with this kind of model is that the message

is seen as relatively unproblematic.

Shannon-Weaver: The Source All human communication has

some source (information source in Shannon's terminology),

some person or group of persons with a given purpose, a reason for

engaging in communication. You'll also find the terms transmitter

and communicator used. We have discussed sender in detail in our

previous lessons.

Shannon-Weaver: The Encoder When you communicate, you

have a particular purpose in mind:

• You want to show that you're a friendly person

• You want to give them some information

• You want to get them to do something

• You want to persuade them of your point of view

and so on. You, as the source, have to express your purpose in

the form of a message. That message has to be formulated in some

kind of code. How do the source's purposes get translated into a

code? This requires an encoder. The communication encoder is

responsible for taking the ideas of the source and putting them in

code, expressing the source's purpose in the form of a message.

It's fairly easy to think in terms of source and encoder when

you are talking on the phone (transmitter in Shannon's

terminology). You are the source of the message and the 'phone is

the encoder which does the job of turning your sounds into

electrical impulses. The distinction is not quite so obvious when

you think of yourself communicating face-to-face.

In person-to-person communication, the encoding process is

performed by the motor skills of the source - vocal mechanisms (lip

and tongue movements, the vocal cords, the lungs, face muscles

etc.), muscles in the hand and so on. Some people's encoding

systems are not as efficient as others'. So, for example, a

disabled person might not be able to control movement of their

limbs and so find it difficult to encode the intended non-verbal

messages or they may communicate unintended messages. A person who

has suffered throat cancer may have had their vocal cords removed.

They can encode their messages verbally using an artificial aid,

but much of the non-verbal messages most of us send via pitch,

intonation, volume and so on cannot be encoded.

Shannon was not particularly concerned with the communication of

meanings. The inclusion of the encoding and decoding processes is

very helpful to us since it draws our attention to the possibility

of a mismatch between the operation of the encoding and decoding

devices, which can cause semantic noise to be set up. With good

reason, the source of the message may wonder whether the picture in

the receiver's head will bear any resemblance to what's in his/her


Shannon-Weaver: The Message The message of course is what

communication is all about. Whatever is communicated is the

message. Denis McQuail (1975) in his book Communication

writes that the simplest way of regarding human communication is

'to consider it as the sending from one person to another of

meaningful messages'.

The Shannon-Weaver Model, in common with many others separates

the message from other components of the process of communication.

In reality, though, you can only reasonably examine the message

within the context of all the other interlinked elements. Whenever

we are in contact with other people we and they are involved in

sending and receiving messages. The crucial question for

Communication Studies is: to what extent does the message received

correspond to the message transmitted? That's where all the other

factors in the communication process come into play. The

Shannon-Weaver model and others like it tends to portray the

message as a relatively uncomplicated matter. Note that this is not

a criticism of Shannon since meanings were simply not his


Frequently the messages have meaning that is they refer

to or are correlated according to some system with certain physical

or conceptual entities. These considerations are irrelevant to the

engineering problem.

This was particularly emphasized in Warren Weaver's introduction

to Shannon's paper:

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 may however be a criticism of the application of Shannon's

model to the more general area of human-to-human communication.

Meanings are assumed to be somehow contained within the signs used

in the message and the receiver can, as it were, take them out

again. Matters such as the social context in which the message is

transmitted, the assumptions made by source and receiver, their

past experiences and so on are simply disregarded. In this respect,

models, which incorporate such factors, are probably more revealing

of the complexity of the communication process.

Shannon-Weaver: The Channel

You tap on a membrane suspended above a steadily flowing jet of

water. The air under the membrane causes slight deflections in the

jet of water. A laser is aimed at a receiver. The jet of water

flows through the laser beam, deflecting it from its target. Every

time the movement of the air deflects the water jet, the laser beam

hits its target. The laser receiver is connected to a computer,

which takes each 'hit' and turns it into a 1 and each miss and

turns it into a 0. The computer sends this etc. etc....

You get the idea: the air waves, the jet of water and so on are

all channels. The words channel and medium are often used

interchangeably, if slightly inaccurately. The choice (a pretty

stupid one above) of the appropriate channel is a vitally important

choice in communication. It's obvious that you don't use the visual

channel to communicate with the blind or the auditory channel with

the deaf, but there are more subtle considerations to be taken into

account as well. A colleague of mine was clearly much more

responsive to visual communication than I. To elucidate his

arguments he would inevitably grab a pencil and a piece of paper

and sketch out complex diagrams of his arguments. Though they may

have helped him to clarify his ideas, they merely served to confuse

me, who would have preferred a verbal exposition. It's curious that

in the college where I work many students who are dyslexic or have

other learning difficulties end up studying information technology

in so-called flexible learning centres. Bearing in mind the

statement above that "the choice of the appropriate channel is a

vitally important choice in communication", it's less than obvious

how a student who has difficulty reading and writing can have their

needs met by a learning model which boils down in essence to 'read

this; it will tell you what to write'.

Shannon-Weaver: Physical noise

Shannon is generally considered to have been primarily concerned

with physical (or 'mechanical' or 'engineering') noise in the

channel, i.e. unexplained variation in a communication channel or

random error in the transmission of information. Everyday examples

of physical noise are:

• A loud motorbike roaring down the road while you're trying to

hold a conversation

• Your little brother standing in front of the TV set

• Mist on the inside of the car windscreen

• Smudges on a printed page

• 'Snow' on a TV set

It might seem odd to use the word noise in this way, unless

perhaps you're a hi-fi buff, in which case you'll be familiar with

looking up the claimed 'signal-to-noise ratio' for the various bits

of equipment you buy. In this technical sense, 'noise' is not

necessarily audible. Thus a TV technician might speak of a 'noisy

picture'. Generally speaking, in this kind of everyday

communication, we're fairly good at avoiding physical noise: we

shout when the motorbike goes past; you clout your little brother;

cars have demisters.

However, it is possible for a message to be distorted by

channel overload. Channel overload is not due to any noise

source, but rather to the channel capacity being exceeded. You may

come across that at a party where you are holding a conversation

amidst lots of others going on around you or, perhaps, in a

Communication lesson where everyone has split into small groups for

discussion or simulations.

Shannon and Weaver were primarily involved with the

investigation of technological communication. Their model is

perhaps more accurately referred to as a model of

information theory (rather than communication theory).

Consequently, their main concern was with the kind of physical (or

mechanical) noise discussed above.

Shannon-Weaver: The Decoder Just as a source needs an

encoder to translate her purposes into a message, so the receiver

needs a decoder to retranslate. The decoder (receiver in

Shannon's paper) is an interesting and very useful development

over, say, the Lasswell Formula.

If you take a look at our discussion of the receiver, you'll see

that we considered how, for example, a blind person would not have

the equipment to receive whatever non-verbal messages you send in

the visual channel.

The notion of a decoder reminds us that it is quite possible for

a person to have all the equipment required to receive the

messages you send (all five senses, any necessary technology and so

on) and yet be unable to decode your messages.

"An_obvious_example_would_be:" id="An_obvious_example_would_be:">An

obvious example would be:

ولكن لا شيء مثير للاهتمام

You can see it. You probably guess that it's a language, maybe

even that it's Arabic. You probably don't understand it, though. In

fact, it is Arabic and it does mean (but nothing very interesting).

You cannot decode my message, encoded to you in that short

sentence, by you. You have the appropriate receiving equipment, but

no decoder. You don't understand the code. Can you think of where

you might come across a similar inability to decode where the

English language is concerned? Suppose you've been reading around

Communication Studies and have come across a reference to the

philosopher Immanuel Kant. So you ask your teacher about him. She

replies, "Well, the Critique of Pure Reason is essentially all

about answering the question: how are synthetic judgments a priori

possible?" Eh? You probably have a meaning for every one of those

words, except perhaps 'a priori'. You might perhaps guess that she

is using the title of one of Kant's works in her answer. But the

statement is incomprehensible unless you know the

technical jargon of philosophy. You can't decode the message -

and your teacher is a pretty lousy teacher for having failed to

predict your inability to decode it (or for having accurately

predicted your inability and using it as an excuse to show


Shannon-Weaver: The Receiver

For communication to occur, there must be somebody at the other

end of the channel. This person or persons can be called the

receiver. To put it in Shannon's terms, information

transmitters and receivers must be similar systems. If they are

not, communication cannot occur. (Actually Shannon used the term

destination, reserving the term receiver for what we

have called decoder. However, I think the terminology I have

been using is more common in the broader understanding of

'communication theory' as distinct from Shannon's information


What that probably meant as far as he was concerned was that you

need a telephone at one end and a telephone at the other, not a

telephone connected to a radio. In rather more obviously human

terms, the receiver needs to have the equipment to receive the

message. A totally blind person has the mental equipment to decode

your gestures, but no system for receiving messages in the visual

channel. So, your non-verbal messages are not received and you're

wasting your energy. See also the Lasswell Formula for a more

detailed discussion of 'receiver'.

Shannon-Weaver: Feedback

Feedback is a vital part of communication. When we are talking

to someone over the phone, if they don't give us the occasional

'mmmm', 'aaah', 'yes, I see' and so on, it can be very

disconcerting. . This lack of feedback explains why most of us

don't like to answer phones. In face-to-face communication, we get

feedback in the visual channel as well - head nods, smiles, frowns,

changes in posture and orientation, gaze and so on. Advertisers

need feedback, which they get in the form of market research from

institutions like ORG MARG, IMRB and other individual research

agencies.. How else would they know if their ads are on the right

track? Broadcasters need feedback, which they get from TRP ratings.

Politicians need feedback, which they get from public opinion polls

and so on.

Why do people often have difficulty when using computers, when

they find it perfectly easy to drive a car? You'd think it should

be easier to operate a computer - after all there are only a few

keys and a mouse, as against levers, pedals and a steering wheel. A

computer's not likely to kill you, either. It could be due to the

lack of feedback - in a car, you've the sound of the engine, the

speed of the landscape rushing past, the force of gravity. Feedback

is coming at you through sight, hearing and touch -overdo it and it

might come through smell as well! With a computer, there's very

little of that.

However, it has to be said that the model's separation of the

communication process into discrete units has proved fruitful and

has formed the basis of several other models, which provide some

more insightful elaboration of the human communication process.

However, in disregarding meaning it may well be downright

misleading. Those researchers who take this model and simply slap

meaning on top of it are probably even

"more_misleading." id="more_misleading.">more misleading.

"br_/" id="br_/">

"c._Weaknesses" id="c._Weaknesses">c. Weaknesses

i. Not analogous to much of human communication.

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1.) "Only a fraction of the information conveyed in interpersonal

encounters can be taken as remotely corresponding to the teletype

action of statistically rare or redundant signals."

"h2heading h6" style="color: rgb(0, 0, 0);" name=




2.) "Though Shannon's technical concept of information is

fascinating in many respects, it ranks among the least important

ways of conceiving of what we recognize as "information." "

ii. Only formal-does not account for content

"h2heading h6" style="color: rgb(0, 0, 0);" name=




1.) Mortensen: "Shannon and Weaver were concerned only with

technical problems associated with the selection and arrangement of

discrete units of information-in short, with purely formal matters,

not content. Hence, their model does not apply to semantic or

pragmatic dimensions of language. "

style="color: rgb(0, 0, 0);" name=




2.) Theodore Roszak provides a thoughtful critique of Shannon's

model in The Cult of Information. Roszak notes the unique

way in which Shannon defined information:

Once, when he was explaining his work to a group of prominent

scientists who challenged his eccentric definition, he replied, "I

think perhaps the word 'information' is causing more trouble . . .

than it is worth, except that it is difficult to find another word

that is anywhere near right. It should be kept solidly in mind

that [information] is only a measure of the difficulty in

transmitting the sequences produced by some information source"

[emphasis added]

"color: rgb(0, 0, 0);" name=




3.) As Roszak points out, Shannon's model has no mechanism for

distinguishing important ideas from pure non-sense:

In much the same way, in its new technical sense,

information has come to denote whatever can be coded for

transmission through a channel that connects a source with a

receiver, regardless of semantic content. For Shannon's purposes,

all the following are "information":

E = mc2

Jesus saves.

Thou shalt not kill.

I think, therefore I am.

Phillies 8, Dodgers 5

'Twas brillig and the slithy roves did gyre and gimble in the


And indeed, these are no more or less meaningful than any string

of haphazard bits (x!9#44jGH?566MRK) I might be willing to pay to

have telexed across the continent.

As the mathematician Warren Weaver once put it, explaining

"the strange way in which, in this theory, the word 'information'

is used .... It is surprising but true that, from the present

viewpoint, two messages, one heavily loaded with meaning and the

other pure nonsense, can be equivalent as regards information"

[emphasis added].

iii. Static and Linear

"color: rgb(0, 0, 0);" name=




1.) Mortensen: "Finally, the most serious shortcoming of the

Shannon-Weaver communication system is that it is relatively static

and linear. It conceives of a linear and literal transmission of

information from one location to another. The notion of linearity

leads to misleading ideas when transferred to human conduct; some

of the problems can best be underscored by studying several

alternative models of communication."

"i2./i_iBerlo's_S-M-C-R,_1960/i" id=

"i2./i_iBerlo's_S-M-C-R,_1960/i">2. Berlo's S-M-C-R,


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