Message Systems and Communication Theory

    BACKGROUND

    Modern Communication Theory is based on mathematical theorems developed by Claude Shannon, an engineer and researcher at Bell Laboratories, in 1948. Shannon's original theory (also known as "information theory") was later elaborated and given a more popular, non-mathematical formulation by Warren Weaver, a media specialist with the Rockefeller Foundation. In effect, Weaver extended Shannon's insights about electronic signal transmission and the quantitative measurement of information flows into a broad theoretical model of human communication, which he defined as "all of the ways by which one mind may affect another."

    The effectiveness of human communication, Weaver asserted, may be measured by "the success with which the meaning conveyed to the receiver leads to the desired conduct on his part." He thus introduced concepts of human purpose and reaction into what had originally been a set of highly technical equations for analyzing and evaluating the transmission of messages.

    S-M-C-R

    Both mathematical and diagrammatic in character, the Shannon-Weaver model measures the efficiency and flexibility of a communication system. It is sometimes referred to as the S-M-C-R model, a mnemonic formula representing the sequence of its main components (Sender-Message-Channel-Receiver).

    In general, for any message system--from computers linked by modems to tin cans connected by string--we can identify and evaluate the following basic components:

Sender (or Encoder): An information source; a person or device that originates a message.

Receiver (or Decoder): The audience for a message. Also known as the addressee.

Message: The actual information or signal sent from a sender to a receiver. The "content" of a communique.

Medium (or Channel): The method used to transmit a message (e.g., print, speech, telephone, smoke signals, etc.).

Noise: Technical or semantic obstacles; that is, anything that interferes with the clear transmission of a message (e.g., low visibility, poor ink quality, static electricity).

Interpretation: All operations that a receiver performs in order to decode and understand a message.

Feedback: Information about a message that a receiver sends back to the sender; the receiver's reaction or response to a communique.

    The components of a typical communication system, and the relationships between those components, are depicted graphically in the following illustration:

  Harold Lasswell, a communications expert famous for his invention of content analysis and his research on propaganda techniques, probably provided the best characterization of the Shannon-Weaver model when he defined communication as essentially a matter of "who says what in which channel to whom and with what effects?"

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