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The Encode-Decode Model of Communication

Sharing the code

Two language codes

Figure 1. Two different codes

When writing this article an important first decision was to determine which code I would use. That is to say, which particular world language would be used to encode my intended meanings? If, for example, I had chosen the code known as Greek or the code known as Dutch, and you do no understand how to decode these particular languages then my communication attempts would be in vain. In this instance, I have chosen the code known as English and, in particular, British English.

Did you understand the first paragraph in Figure 1? Were you able to decode its meaning? What about the second paragraph in Figure 1?

Well, unless you understand (written) Greek (first paragraph) or Dutch (second paragraph) you would not have been able to decode the particular language and glean its meaning. In fact, the first two paragraphs have essentially the same meaning as the opening paragraph of this article above, written of course in English. I am assuming that you can decode the opening paragraph or else you would most likely not have selected this webpage in the first place! In reality, the choice of selecting these codes was unavailable to me, as I do not speak/understand either of these particular world languages. Consequently, I cannot vouch for the accuracy of the translations into Greek or Dutch. I trusted the translations to an online service ( – I merely inserted the English code and the web-based software did the rest.

The point I am illustrating is that language is, in one sense, a code and in order to share meanings linguistically we must share the same code. Now, a code is simply “a device that generates pairs made up of a message and a signal” (Sperber, 1994:179). For example, the Morse code pairs each letter of the alphabet with a series of short or long beeps. The renowned maritime distress call ‘SOS’ for instance consists of three short beeps, three long beeps and three short beeps transmitted as a string:


In a similar manner, it is argued, a language pairs linguistic senses and sounds: I must encode my thoughts into a mutually understandable form that you can subsequently decode. In sum, we must share a common language. Reasoning such as this has given rise to the so-called encode-decode model of communication and diagrammatic representations such as Figure 2.

encode-decode model of communication image

Figure 2. Traditional Encode-Decode Model of Human Communication

Encode-decode communication models as represented in Figure 2 come under the general heading of transmission models. Such models have been in use for a considerable time, e.g. the Shannon-Weaver model (Shannon, 1948); the Osgood and Schramm model (Schramm, 1954); The Speech Chain (Denes and Pinson, 1993).

At their most basic, transmission models consist of three parts:

  1. source
  2. channel
  3. receiver

A sender encodes a message, which is transmitted through an appropriate channel (in the case of speech, in a face-to-face interaction, this is air), to a receiver who subsequently decodes the message. This basic model can be expanded to six elements:

  1. source
  2. encoder
  3. message
  4. channel
  5. decoder
  6. receiver

In summary, the claim is that a source (a person with a reason for communicating) first accesses his or her communication encoder (a device that manipulates the source’s thoughts into some kind of code) in order to formulate a message. We have already noted that when messages are spoken in face-to-face interactions the channel is the air between the speaker and the listener. In the same way that a source requires an encoder to render his or her thoughts into messages, so a receiver requires a decoder to decipher the message. The receiver is, self-evidently, the person(s) at the end of the channel.

Put another way, a person (source) formulates an idea – a concept – and encodes this concept linguistically, i.e. into strings of sounds, syllables and words, then transmits this encoded thought as a sound wave, whereupon another person (receiver) decodes the sound wave back into the original concept. The speaker, therefore, encodes his or her intended message into a signal that is decoded by the listener who uses an identical copy of the code. According to such encode-decode models, then, all that is required is an appropriate encoding and decoding algorithm, i.e. a set of precise, unambiguous instructions for transforming a set of initial conditions (thoughts) into a set of final conditions (sound waves), and vice versa. The implication is, once again, that if the speaker and listener both share the same code – a common language – then communication is possible. Language allows humans to translate thoughts into strings of sounds, syllables and words, and to translate strings of sounds, syllables and words into thoughts:

Encoding-decoding algorithms

Humans, therefore, can function both as encoders of linguistic meaning and decoders of linguistic sound. Suppose, for example, that I wish to communicate some meaning to you, perhaps the thought that I can see a small furry animal with a leg in each corner, whiskers at one end, a tail at the other, sharp retractable claws, it drinks milk and says, “Meow!” First, I need to look up in my mental lexicon the word that is used in English to encode this meaning. Within a matter of moments I readily settle on the word cat. I then produce the word/sound cat, pronounced c-a-t, so that the person to whom I wish to communicate this thought might hear it. On hearing this word/sound, the listener then looks up in his or her mental lexicon the meaning associated with it and readily decodes the meaning as referring to a small furry animal with a leg in each corner, whiskers at one end, a tail at the other, sharp retractable claws, it drinks milk and says, “Meow!” Inasmuch as the listener is successfully able to decode my meaning then one may claim that a thought has been shared and, therefore, that communication has taken place. This appears to be a fitting explanation of human communication, as all that is required is that the people communicating with each other share the same code, in this case the language known as English. In this way, they are able to encode meanings into sounds and decode the sounds into their meanings.


The above explanation all seems fairly straightforward. However, there are several difficulties with this model, such as the fact that it does not take into account the backwards-and-forwards dynamic nature of spoken interaction, and that it does not address the issue of how we both make meaning and infer meaning. The following article deals with both of these issues:


Denes, P.B. and Pinson, E.N. (1993) The Speech Chain: Physics and Biology of Spoken Language Basingstoke: W.H. Freeman & Co.

Schramm, W. (1954) ‘How communication works’ in Schramm W (ed.), The Process and Effects of Mass Communication Urbana: University of Illinois Press.

Shannon, C. (1948) ‘A mathematical theory of communication’ Bell System Technical Journal Vol. 27, pp. 379–423, 623–656, July, October, 1948. [The paper has appeared in a number of republications since. You can download a pdf version of the paper from Bell Labs at (accessed 17.01.2011).]

Sperber, D. (1994) ‘Understanding Verbal Understanding’ in Khalfa, J. (ed.) What is Intelligence? Cambridge University Press (1994), 179-198.