Communication models in extension
Communication models from Aristotle and Lasswell to Shannon-Weaver, Berlo and Schramm, two-step flow, participation, and channel cost sums.
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Extension is, at its heart, communication: researchers, extension workers, companies and farmers exchanging information, ideas and experience. A message that is technically perfect can still fail if it uses jargon, arrives through a channel farmers do not trust, comes at the wrong time, or ignores what farmers already know. Communication models break the process into parts, so that each can be planned and improved.
Communication models and their use in extension are a standard exam topic in agricultural extension and rural development.
The elements of communication
Most models share a few elements:
- Source (communicator, sender): who starts the communication.
- Message: the content, its treatment and language.
- Channel (medium): face-to-face, group meetings, demonstrations, print, radio, television, phone, internet.
- Receiver (audience): who gets the message.
- Effect (response): change in knowledge, attitude, skill or practice.
- Noise: anything that distorts the message.
- Feedback: the receiver's response, which lets the source adjust.
Classic models
Aristotle
In his Rhetoric (fourth century BCE), Aristotle described persuasion through a speaker, a speech and an audience, and stressed the speaker's credibility (ethos), emotional appeal (pathos) and logic (logos), all still relevant to extension.
Lasswell (1948)
Harold Lasswell summarised communication as: who says what, in which channel, to whom, with what effect? It is a useful checklist for planning an extension campaign, though it presents communication as one-way.
Shannon and Weaver (1949)
Developed by Claude Shannon for telephone engineering and explained by Warren Weaver, this model has an information source, transmitter, channel, receiver and destination, with noise interfering in the channel. In extension, noise includes technical problems (a poor radio signal) and semantic noise (jargon, unfamiliar units, a language the farmer does not speak well).
Berlo's SMCR model (1960)
David Berlo described Source, Message, Channel and Receiver, emphasising that the source and receiver each have communication skills, attitudes, knowledge, social system and culture. Communication works best when these overlap, which is why extension workers who understand farmers' language and circumstances communicate better.
Schramm (1954)
Wilbur Schramm showed communication as two-way and circular: each party encodes, interprets and decodes, and understanding depends on a shared field of experience. Feedback is central.
Leagans' model
J. Paul Leagans, writing on extension education, described six elements: communicator, message, channel, treatment of the message, audience and audience response, a model widely taught in extension courses in South Asia.
How information spreads: two-step flow
In 1944, P. Lazarsfeld, B. Berelson and H. Gaudet, studying voters, found that mass media often reach the public indirectly: ideas flow from media to opinion leaders, and from them to others. This two-step flow (later multi-step flow) explains why extension works through contact farmers, lead farmers and local leaders, and why trusted neighbours influence adoption more than distant experts. It connects with the theory of diffusion of innovations.
From persuasion to participation
Early extension communication aimed mainly to persuade farmers to adopt recommended practices. Critics, notably the Brazilian educator Paulo Freire in Pedagogy of the Oppressed (1970) and in his essay on extension, argued that this treated farmers as empty vessels. Participatory and dialogic communication instead treats farmers as partners who share knowledge, define problems and test solutions, as in farmer field schools, participatory video and community radio.
Fidelity and barriers
Fidelity is how faithfully a message arrives as intended. It falls when the source lacks credibility, the message is too complex or badly timed, the channel is noisy, or the receiver is distracted, sceptical or lacks resources to act. Common barriers in extension include language and literacy, gender norms that exclude women from meetings, distance, and mistrust after earlier bad advice.
Choosing channels
| Channel | Strengths | Limits |
|---|---|---|
| Individual visits, phone advice | personal, tailored, trusted | costly per farmer |
| Group meetings, demonstrations, field days | seeing is believing; discussion | reaches dozens, not thousands |
| Radio, television, video | wide reach, low cost per person, local languages | one-way unless combined with call-ins |
| SMS, voice messages, apps, social media | timely, cheap, interactive | need phones, literacy, connectivity |
| Print (leaflets, posters) | lasting reference | needs literacy |
Combining channels, such as a radio programme followed by demonstrations and a phone helpline, is usually most effective.
Cost per adopter for three channels
An extension agency promotes a new seed treatment.
| Channel | Cost | People reached | Adoption | Adopters | Cost per adopter |
|---|---|---|---|---|---|
| Radio series | 600 | 50,000 listeners | 2% | 1,000 | 0.60 |
| SMS (4 messages) | 0.01 × 4 × 20,000 = 800 | 20,000 | 3% | 600 | 1.33 |
| 20 field demonstrations | 20 × 200 = 4,000 | 1,000 attendees | 30% | 300 | 13.33 |
Radio is cheapest per adopter, but the demonstrations persuade a much larger share of those they reach, and their adopters can become local examples for others. A combined plan might use radio and SMS for awareness and demonstrations to convince opinion leaders, whose example reaches many more through the two-step flow.
Key points
- Communication elements: source, message, channel, receiver, effect, noise and feedback.
- Models: Aristotle (speaker, speech, audience), Lasswell (who says what, in which channel, to whom, with what effect), Shannon–Weaver (noise), Berlo SMCR, Schramm (two-way, field of experience), Leagans (six elements).
- Two-step flow: media influence opinion leaders, who influence others.
- Participatory communication (Freire) treats farmers as partners.
- Match channels to purpose and audience; combine mass media with personal methods.
What the exams ask
- School-leaving and entrance papers: elements of communication and examples of extension methods and media.
- Degree and research-fellowship entrances: classic models and their elements, noise and feedback, fidelity, two-step flow, and selection of channels.
- Professional examinations: planning extension communication campaigns, participatory communication, and evaluating media effectiveness.
Described in general terms: the kind of examination, not a past paper. Laisha never reproduces exam questions.
Questions people ask
What is semantic noise in extension?
Distortion caused by words and symbols the farmer does not understand, such as scientific names, unfamiliar units or technical jargon. Using local terms, examples and pictures reduces it.
Why does feedback matter so much?
Without feedback, the source cannot know whether the message was understood or useful. Questions and results from farmers let extension correct misunderstandings and improve recommendations.
Are mass media enough to change practices?
Rarely on their own. They create awareness cheaply, but adoption of new practices usually needs demonstrations, discussion and support from trusted people.
Sources
- Lasswell, H. D. "The structure and function of communication in society." In Bryson, L. (ed.) The Communication of Ideas. Harper, 1948.
- Shannon, C. E. and Weaver, W. The Mathematical Theory of Communication. University of Illinois Press, 1949.
- Berlo, D. K. The Process of Communication. Holt, Rinehart and Winston, 1960.
- van den Ban, A. W. and Hawkins, H. S. Agricultural Extension, 2nd edition. Blackwell Science, 1996.
- Freire, P. Education for Critical Consciousness (including "Extension or Communication"). Seabury Press, 1973.
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