to in-depth examinations of the communication processes among various actors within and external to the agricultural system. This field refers to the participatory extension model as a form of public relations-rooted two-way symmetric communication based on mutual respect, understanding, and influence between an organization and its stakeholders. Agricultural communication can take three modes—face-to-face training, training "products" such as manuals and videos, or information and communication technologies (ICTs), such as radio and short message system (SMS). The most effective systems facilitate two-way communication and often combine different modes. Four paradigms of agricultural extension Any particular extension system can be described in terms of both how communication takes place and why it takes place. It is not the case that paternalistic systems are always persuasive, nor is it the case that participatory projects are necessarily educational. Instead there are four possible combinations, each of which represents a different extension paradigm, as follows: Technology transfer (persuasive + paternalistic): This paradigm was prevalent in colonial times and reappeared in the 1970s and 1980s when the "Training and Visit" system was established across Asia. Technology transfer involves a top-down approach that delivers specific recommendations to farmers about the practices they should adopt. Advisory work (persuasive + participatory): This paradigm can be seen today where government organizations or private consulting companies respond to farmers' inquiries with technical prescriptions. It also takes the form of projects managed by donor agencies and NGOs that use participatory approaches to promote predetermined packages of technology. Human resource development (educational + paternalistic): This paradigm dominated the earliest days of extension in Europe and North America, when universities gave training to rural people who were too poor to attend full-time courses. It continues today in the outreach activities of colleges around the world. Top-down teaching methods are employed, but students are expected to make their own decisions about how to use the knowledge they acquire. Facilitation for empowerment (educational + participatory): This paradigm involves methods such as experiential learning and farmer-to-farmer exchanges. Knowledge is gained through interactive processes and the participants are encouraged to make their own decisions. The best known examples in Asia are projects that use Farmer Field Schools (FFS) or participatory technology development (PTD). There is some disagreement about whether or not the concept and name of 'extension' really encompasses all four paradigms. Some experts believe that the term should be restricted to persuasive approaches, while others believe it