When you communicate, you have a particular purpose in mind:

• You want to show that you are 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. In fact, it is Wilbur Schramm’s model of 1954, which places greater emphasis on the processes of encoding and decoding. 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 own. Schramm went on to introduce the notion of a ‘field of experience’, which shows a much greater awareness of the subtleties involved in human-to-human communication, drawing our attention to the numerous shared socio-cultural factors which are necessary for successful communication to take place.