Friday, May 05, 2006

Shannon-Weaver model of communication

Claude Shannon (1916-2001) is considered one of the founding fathers of the communications age.

Shannon's 1937 master’s thesis on enabling electrical switches to do logic was the foundation of digital circuit design. He became a mathematical engineer and research scientist at the Bell Telephone Company. During the war he worked on fire-control systems and cryptography. In 1948 he worked on the problem of achieving maximum telephone line capacity with minimum distortion. As a result, he developed a mathematical theory of signal transmission which he published in the article "A Mathematical Theory of Communication".

The theory was intended purely for telephones. But when fellow American scientist Warren Weaver (1894-1978) applied Shannon's concept of information loss to interpersonal communication, an ingenuously effective model of communication was created.

The model expands on Harold Laswell’s theory of communication which states:
"Who (says) What (to) Whom (in) What Channel (with) What Effect"

The Shannon-Weaver model deconstructs communication into the following six elements:
1. a source
2. an encoder
3. a message
4. a channel
5. a decoder
6. a receiver
There are also three other factors: physical noise, semantic noise and feedback.

The source is the sender of the message; someone with a purpose of communication. The communicator wants to achieve some end: to show friendship, give information, ask for something, convince or simply share something. The communicator’s message is the code and the encoder turns a purpose into a something that can be delivered as a message. Human encoders include the human larynx, facial muscles, arm movements. Examples of non-human encoders are telephones, alphabets and modems.

The message is the centrepiece of communication. A simple definition of communication is “to consider it as the sending from one person to another of meaningful messages”. In a sense, the message is not an element but merely the combination of all the other elements. The key question is: is the message received the same as the message sent?

Shannon was unfussed about message meaning because it was irrelevant to his engineering problem. As a result the model does not deal effectively with issues such as assumptions, social context, or the impact of knowledge and memory. See the Berlo SMCR model for a more detailed look at these complexities.

The Channel is a path; it is the medium on which the message travels. Marshall McLuhan observed the path is all with his dictum "the medium is the message". In the model, this can be read as the journey being more important than the destination. This is borne out in the real world where communication companies such as News Corp, AOL Time Warner and Disney are among the world’s most powerful organisations.

The existence of physical noise is the problem that Shannon was trying to solve in the first place. But noise is not just an audible sensation. The roar of passing traffic, interference on a radio broadcast, poor TV reception and fog on glasses are all examples of physical noise. As is channel overload due to lack of bandwidth.

If Shannon’s engineering problem was physical noise, the biggest problem of human communication is the existence of semantic noise. Semantic noise occurs when there is a mismatch between the encoder and the decoder. Examples include distraction, inability to translate the message, incorrect emphasis, attitude to the sender and attitude to the message.

It is easy to see how being distracted is an impediment to communication. There may not be any physical noise, but for some reason the receiver is not paying attention. “You weren’t listening!” is a common complaint of message senders. The receiver was present but was distracted by something else.

If the message is not delivered in the lingua franca, then the receiver is not going to understand, regardless of distractions. And even if they are speaking the same language, the message may be missed if the wrong part of it is emphasised. People may remember a wonderfully inventive ad but not the product it was spruiking. A biased attitude to either the sender or the message is also likely to produce semantic noise. Consider the responses: "What would he know?" or "I don’t believe in that mumbo-jumbo!"

Assuming the message gets past all these noises, a decoder is needed to retranslate at the other end. It could be an answering machine, a TV screen, ears or a mobile phone. But it is more than equipment. There are endless cultural factors that also influence how the message is translated. Here is where assumptions made by the sender are tested.

The destination is the receiver. Without a receiver, there is no-one to communicate with.

But the destination is not the final step. The final step goes back to the start. The receiver provides feedback. This is the heartbeat of communication. Without it, communication is a very dull affair. Lack of feedback explains why most people are awkward talking to answering machines. Mathematician Norbert Wiener (who coined the word ‘cybernetics’) defined the feedback principle to mean “behaviour is tested with reference to its result and success or failure of this result influences the future behaviour”.

End of message. Any comments?


Anonymous said...

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Anonymous said...

simply fantastic information.Its really helpful for students........

vaibhav said...

nicely written n explained by the writer 10 on 10 for him

somayeh said...

thank you. it is explained very easily so it was digestable for me