One-way and two-way communication During the Second World War, Shannon and Weaver developed a communication theory that serves as the basis of many other communication theories, and is described as linear process. They described the transfer of a message as follow: the signal is sent from the source by the sender through the channel to the receiver and further to the destination. The term noise was described as everything that is added to the signal between the sender and receiver, and that was not intended by the source but affects reception of the message. Shannon and Weaver identified three levels of problems: technical problems (How exactly can communication symbols be transferred?), semantic problems (How exactly can the transferred symbols be explained?), and effectiveness problems (How effectively does the received message affect the desired behaviour?). The theory also demonstrates how redundancy facilitates the accuracy of decoding. Redundancy is what is predictable or conventional in a message. A message that is high in predictability is redundant and contains less information. The opposite of redundancy is entropy, which means a message low in predictability and containing a great deal of information. Convention is a major source of redundancy, as we check the accuracy of a message we receive in relation to what is probable, depending on our experience of the code, the context, and the type of message. Structuring one’s message according to conventions is one way to decrease the entropy and increase the redundancy.20, 21 Shannon and Weaver’s theory is described as one-way communication, which has advantages because it is rapid, looks and sounds proper, and the sender feels in control. Disadvantages of one-way communication are that isrequires planning, the responsibility lies with the sender, there is no feedback, and the receiver may not be paying adequate attention.18 Feedback, which is found in two-way communication, is described as closing the communication loop and may prevent misunderstanding18, 22 in the receiver’s interpretation of the original meaning of a message. Using feedback has advantages in that it is reliable and effective, permits checking and correction, requires less planning, the receiver has more confidence and makes more correct judgements about accuracy, both the sender and receiver have responsibility, and the sender and receiver work together to achieve shared understanding.18 Flin et al.18 described three types of feedback: “1) Informational – the receiver provides a non-evaluative response, e.g. provides an objective statement in response to the initial statement. 2) Corrective – the receiver challenges or corrects the sender’s message, e.g. questions or queries the initial statement to gain clarification. 3) Reinforcing – the receiver acknowledges clear receipt of the message, e.g. checks understanding of the message.”18 (p.73) There is also a term called closed-loop communication where the sender also verifies the message; it is described as follows: 1) the sender transmits the message, 2) the receiver acknowledges the message by check-back and 3) the sender verifies that the message has been interpreted correctly.23