Claude Shannon was a telephone transmission engineer, and his interest was not in mass communication as such but in the understanding and improvement of telephone communication. He was concerned to show what happened to “information bits” as they “travel” from the source to the receiver. In the process, he isolated the key elements of the communication process, i.e. the source, message, transmitter, channel, receiver and destination. His colleague, Warren Weaver, later added the element of feedback, the absence of which was identified as a weakness of the initial Shannon model. Another weakness, from the point of view of human communication, was that the theory decidedly excluded
“meaning”, which is a cardinal consideration in human communication but which could befuddle Shannon’s engineering treatise. However, the key elements of the communication process as identified by Shannon provided a bearing for all later graphic communication models. These elements may be explained as follows:-
i. The Communication Chain: All communications are composed of chains or systems; and a system or chain is no stronger than its weakest element or link.
ii. The Information/Communication Source: The entity (individual, group or organisation) that originates the message.
Otherwise called encoder, originator, etc.
iii. The Message: The information itself, which may be verbal or nonverbal, visual, auditory, tactual or olfactory.
iv. The Transmitter: The person, establishment (or equipment) that encodes and transmits the message on behalf of the source (the transmitter may itself be the source).
v. The Channel: The avenue through which the message is transmitted to the receiver. It may be electrical, mechanical or human. It is often used interchangeably with “medium”.
vi. The Receiver: The entity (individual, group, organisation) at which the message is targeted; otherwise called decoder, audience, etc.
vii. The Destination: The central “nervous system” (e.g. the human brain) where the message is processed for final use.
viii. Noise: Anything added to the information signal but not intended by the information source, and therefore causing distortion in the message. Shannon recognised only “channel noise” but later studies interpolated “semantic noise” which arises from verbal mismanagement; and “psychological noise”, resulting from the current state of the mind of the participants.
ix. Feedback: The signal relayed from the receiver back to the source about the accuracy of reception of the message.
Shannon also added the concepts of:
x. Channel Capacity:
· A channel’s absolute ability to transmit the output of an information source (i.e. whether it is able to do so at all).
· The amount of information a channel can transmit per unit time. For example, it is known that the eye can resolve and transmit far more information than the brain can process and store within a given time.
xi. Redundancy: The part of the message, which is not determined by free choice of the sender (i.e. which is not “entropy”,
“randomness”, or “uncertainty” in the information theory sense).
Redundancy is superfluous because, without it, the message would be essentially complete (In mass comm terms, consider the redundancy involved in prime-time news — the “headlines”, the
“main news”, then the “major points”).
xii. The Idea of Correspondence: Systems, including communication systems, can be corresponding or non-corresponding. For example, a written code and a telegraphic code (like the spoken verbal code and electronic code) are non- corresponding. For example, a written code and a telegraphic code (like the spoken verbal code and electronic code) are non-corresponding, so one has to be re-coded or “transcoded” into the other for purposes
of transmission and reception. In information theory terms, communication takes place when two corresponding systems, coupled together through one or more non- corresponding systems, assume identical states as a result of signal transfer along a chain (Schramm: 1954). The coupling is known as the
“gatekeeper point”.
We have gone to this length in discussing the Shannon and Weaver model to let the student see what information theory bequeathed to Mass Communication theory. However, because information Theory represents essentially a structural system, it cannot be used to fully explicate a functional system such as human communication.
Fig. 1: The Shannon and Weaver Model 3.2.2 The Lasswell Model (1948)
At about the same time that Engineer Shannon was proposing his model, social scientist, Harold Lasswell, was also busy analysing the functions of (Mass) Communication in Society. In 1948, he published his findings, in which he assigned three functions to the media, namely:
i. Surveillance of the Environment (the news function);
ii. Correlation of the different parts of the Environment (the editorial function); and
iii. Transmission of the cultural heritage from one generation to the other (the cultural transmission function).
Of immediate relevance to our subject matter here is Lasswell’s proposed verbal model to describe the process through which these communication functions are carried out. To understand this, the Model requires that we answer the questions:
Who ? Says what?
In which Channel ? To Whom ?
With what Effect?
Correspondences can be identified between Lasswell’s verbal model and Shannon’s graphic model as follows:
1) Who ……….... Information Source
2) Say(s) what……….……….. Message
3) (In) which (Channel)………..……….. Channel
4) (To) whom……… Receiver
5) (With) what (Effect)……….….Destination
(Table 1: Correspondences between the Shannon and the Lasswell Models)
With the addition of “How” (and the acronym “5ws and H”), Lasswell’s verbal model has come to provide a working guide for modern journalists.