Linear Model: The linear model shows a sender transmitting messages to a receiver. Once they are finished it is assumed the roles are reversed and the sender becomes the receiver and the receiver becomes the sender. In 1949, two engineers added noise to the equation to show its effect on communication.
Interactive Model: The interactive model adds the variable of dual roles. In this model, it assumes that the parties involved in the communication can be senders and receivers. A big part of this model is the field of experience and feedback. Feedback is a method of sending a message to indicate what they are getting from the conversation. Field of experience is another factor that will dictate how two people communicate. For example: An engineer will speak differently to other engineers as opposed to customers who would not understand the technical aspects.
Transactional Models: Transactional models add the dimension of constant communication between 2 or more parties. Instead of depicting senders/receivers as fulfilling one role at a time, this model portrays them as filling both roles at the same time. Even if you are not the speaker, body language and responses (or even lack of responses) is a form of communication.
Books Model: The books model adds outside influences such as societal forces, culture and context. When two or more people are communicating, factors such as the culture or the context of the discussion will change the messages dramatically. Even when talking to the same person, the conversation will change a lot depending on the location and context. Talking to a friend about sports at home is a lot different than talking to the same friend about family at a