Primary author: Julie Beyrer

Shannon-Weaver Model Julie Beyrer
The Shannon-Weaver model originates from work developed by two research mathematicians at Bell Technology laboratories, Claude Shannon and Warren Weaver (Devlin 2001). Shannon published the first appearance of their work in a paper in the Bell System Technical Journal in 1948; the paper is titled “A Mathematical Theory of Communication” and is available online: http://bstj.bell-labs.com/. The model in Shannon’s paper describes how to efficiently transmit information between a source and a destination. The model specifically deals with the transmission of messages or signals (eg, via telephone, radio, television, etc) from a mathematical and engineering perspective. There are five key components in the model (depicted in the figure below):
1) Information source- “produces a message or sequence of messages to be communicated to the receiving terminal”
2) Transmitter- “operates on the message in some way to produce a signal suitable for transmission over the channel”
3) Channel
4) Receiver- reconstructs the message
5) Destination- the person the message is intended for (Shannon 1948).


The model says that the message has an inherent statistical structure and can be sent in a digital manner. The message’s content does not need to be considered because the message does not affect its transmission from transmitter to receiver. The message may be interrupted if there is “noise” in the channel.
The Shannon-Weaver model was critical in development of computer and digital technologies. It is sometimes referred to as a model of person-to-person communication, but it is not an appropriate communication model in this sense. Its applicability is limited to public health communication in at least two key ways:
1) People are not uniform transmitters and receivers; each person has individual characteristics that must be considered in the process of communicating, and
2) The meaning of the message can affect how the message is received

3) There is no opportunity in the model for an exchange between receiver and transmitter.
These limitations are important public health communicators to understand.
The first limitation (diversity of individual characteristics) has been shown to affect receipt of emergency notifications (eg, a flood warning). “Individuals may listen to the same warning but not comprehend the same message” (Dash & Gladwin 2007). According to Fitzpatrick and Mileti (1991), “people filter information to conform to their pre-existing views of the world.” They state that this filtering effect has consequences of receipt of emergency information. An example is hearing the word “flood”: one person may hear the word “flood” and imagine the severe risk of an inundating wall of water, while another individual hears the same word and does not perceive the risk to be severe (Fitzpatrick & Mileti 1991). Another example is a warning to “get to high ground;” this warning may be understood differently by different individuals: getting high ground for some may be low ground to others. High ground should be defined (eg, “ground higher than the top of City Hall”) (Sorensen & Vogt 2006). The receiver may also hear and interpret a message differently depending on his or her perception or feelings about the transmitter (ie, whether the transmitter is a trusted public official, weather forecaster, neighbor, etc.) or even depending on how the transmitter delivered the message (eg, face-to-face, over the radio, etc) (Baker 1991; Stein et al 2010). These diverse individual characteristics have been called “intrinsic moderators” (Street & Epstein 2008) and include age, gender, race, education, health literacy, clinician attitudes, perceived risk, and others.
The second limitation of the Shannon-Weaver model (ie, message content alters its receipt) is evident in physician-patient communication. The message itself can impact how or even what is received. For example, a diagnosis of common cold would likely not be received in the same way as a diagnosis of breast cancer. The severity of the latter diagnosis might make it more difficult for the individual to take in all of the important information. Patients may selectively hear only parts of the cancer diagnosis but not all because of initial shock (Fallowfield 2008). The MD Anderson Cancer Center has developed a SPIKE protocol for sharing the cancer diagnosis with the patient (Baile et al 2000) that takes into account the fact that the message itself can make its receipt difficult. SPIKE represents a number of strategies, such as ensuring an appropriate setting and understanding the patient’s baseline perceptions, that can used to help minimize the shock and reduce the potential for miscommunication.

A third limitation is the linear, one-way transmission of information in the model. Several public health behavior and education models suggest that structuring communication as an exchange, with the opportunity for the receiver to provide feedback, is important for effective communication. Examples include the diffusions of innovations model (Oldenburg and Glanz 2008) and measures of physician-patient communication (Street and Epstein 2008). In these examples, audience feedback is crucial to communicating, which may include functions not readily associated with “communication” such as validating and responding to patients’ emotions. (Many people think of communication as a 1-way linear transmission of a ‘message,’ similar to the Shannon-Weaver model.)

Three important limitations of the Shannon-Weaver model as a communication model have been described. Health communication models should instead help communicators focus on identifying the target audiences and making appropriate rhetorical decisions to meet the needs of the audience (eg, the STRIKE protocol described previously). They should also help identify opportunities for an exchange of information between communicators and audiences. Other models of communication (eg, Berlo’s source-model-channel-receiver model) have built upon Shannon-Weaver while including more human elements in the model. However, there is no single comprehensive theory of communication.

Communication is important to public health in variety of ways. Good physician-patients communication has been associated with improved physical health, more effective chronic disease management, and better health-related quality of life (Street & Epstein 2008). Good communication can alleviate distress, enhance positive feelings, and facilitate a patient’s ability to cope with stress, uncertainty, or setbacks (Street & Epstein 2008). In the example of emergency situations (eg, responding to local emergencies or natural disasters), effective communication may make the difference between life and death.

References
Baile, W.F., Buckman, R., Lenzi, R., Glober, G., Beale E.A., & Kudelka, A.P. (2000). SPIKES—A six-step protocol for delivering bad news: application to the patient with cancer. Oncologist, 5, 302-311. Doi: 10.1634/theoncologist.5-4-302.
Baker, E. (1991). Hurricane evacuation behavior. Int J Mass Emergencies Disasters, 9, 287-310.
Dash, N., & Gladwin, H. (2007). Evacuation decision making and behavioral responses: individual and household. Natural Hazards Review, 8, 69-77. doi: 10.1061/(ASCE)1527-6988(2007)8:3(69)
Devlin, K. (2001). Claude Shannon. Mathematical Association of America. Available at: http://www.maa.org/devlin/devlin_3_01.html. Accessed 30 October 2010.
Fallowfield, L.J. (2008). Treatment decision-making in breast cancer: the patient-doctor relationship. Breast Cancer Res Treat 112, 5-13. doi 10.1007/s10549-008-0077-3
Fitzpatrick, C., & Mileti, D.S. (1991). Motivating public evacuation. International Journal of Mass Emergencies and Disasters, 9, 137-152.

Oldenburg, B., & Glanz, K. (2008). Diffusion of innovations. In K. Glanz, B.K. Rimer, & K. Viswanath (Eds.), Health behavior and health education (pp. 313-333). San Francisco, CA: Jossey-Bass.

Sorensen J., & Vogt B. (2006). Interactive emergency evacuation guidebook. Oak Ridge National Laboratory Emergency Management Center, Oak Ridge, TN. Available at: http://emc.ornl.gov/CSEPPweb/evac_files. Accessed 02 October 2010
Shannon C. (1948). A mathematical theory of communication. The Bell System Technical Journal. Available at: http://bstj.bell-labs.com/. Accessed 30 October 2010.
Stein R.M., Dueñas-Osorio L., & Subramanian, D. (2010). Who evacuates when hurricanes approach? The role of risk, information, and location. Social Science Quarterly, 91, 816-834.
Street. R.L., & Epstein, R.M. (2008).Lessons from theory and research on clinician-patient communication. In K. Glanz, B.K. Rimer, & K. Viswanath (Eds.), Health behavior and health education (pp.237-269). San Francisco, C