Research on the diffusion of innovations model began with Bryce Ryan and Neal C. Gross investigation (1943) of the diffusion of hybrid seed corn among Iowa farmers. By 1941, about thirteen years after its release by agricultural researchers, this innovation was adopted by almost 100 per cent of Iowa farmers. Ryan and Gross studied the relatively rapid diffusion of hybrid corn in two Iowa communities in order to understand this phenomenon so that it might be applied to the diffusion of other farm innovations. However, the intellectual influence of the hybrid corn study reached far beyond the study of agricultural innovations and outside the rural sociology tradition of diffusion research that Ryan and Gross represented.

Everett Rogers, a professor of communication studies, popularized the theory in his book Diffusion of Innovations; the book was first published in 1962. It’s one of the oldest social science theories. It originated in communication to explain how, over time, an idea or product gains momentum and diffuses (or spreads) through a specific population or social system. The end result of this diffusion is that people, as part of a social system, adopt a new idea, behaviour, or product.   Adoption means that a person does something different than what they had previously (i.e., purchase or use a new product, acquire and perform the new behaviour, etc.). The key to adoption is that the person must perceive the idea, behaviour, or product as new or innovative. It is through this that diffusion is possible.  

Adoption of a new idea, behaviour, or product (i.e., “innovation”) does not happen simultaneously in a social system; rather it is a process whereby some people are more apt to adopt the innovation than others.   Researchers have found that people who adopt an innovation early have different characteristics than people who adopt an innovation later. When promoting innovation to a target population, it is important to understand the characteristics of the target population that will help or hinder the adoption of the innovation. There are five established adopter categories, and while the majority of the general population tends to fall in the middle categories, it is still necessary to understand the characteristics of the target population.

Development underpins change and acceptance of innovations – ideas, practices and technologies. Hence, facilitating the diffusion of innovations is an essential aspect of the development support communication. What is innovation?

Innovation refers to an idea perceived as new by an individual. All innovations need not be new to all people. What is new to one individual may be a known thing for another individual. Hence, the term innovation is applied to an idea which is perceived by an individual or group as something new to that person or to that group.

Diffusion is a process by which an innovation spreads. The diffusion process is the spread of a new idea from its source of creation to the adopters or users. Hence, the essence of the diffusion process is the human interaction, in which one person communicates a new idea to another person. 

There are four elements in any analysis of the diffusion process: (1) innovation, (2) communication of one individual to another, (3) the social system, and (4) the time taken from the stage of innovation to the stage of adoption.

Five distinct stages have been identified by the scholars who studied diffusion and adoption process: (1) Awareness (2) Interest (3) Evaluation (4) Trial and (5) Adoption.

At the awareness stage, there is a broad exposure to innovation, but the individual does not have sufficient information about the innovation. He is yet to get motivated either to seek further information or to act upon it.

At the interest stage, the individual shows interest in the new idea and makes an effort to seek additional information. However, the person is still undecided about its application. The function of the interest stage is mainly to seek and get more information about the idea.

At the evaluation stage, the individual mentally applies the innovation to one’s situation and then decides whether to try it or not.

At the trial stage, the individual uses the innovations on a pilot stage to decide about its utility and relevance to one’s situation. It was observed that most persons would not adopt an innovation without trying it on a pilot basis.

At the adoption stage, the individual decides to continue the innovation. Adoption implies sustained use of the adoption process: The rejection is, thus. a decision not to adopt an innovation. Though, based on the diffusion research, there is no evidence to show that all the five stages will be visible of being scrupulously followed by all the adopters.

While personal communication connotes the direct face to face contact, impersonal communication, mediated through mass communication channels, does not involve face to face exchange of ideas. Communication through the mass media like the print, radio, TV and Mass Medii and Development film is most eff&tive in providing various options and choices. They are effective in drawing the attention of the individuals. Hence, the mass communication channels are found to be most important in the evaluation stage of the adoption sources. Inter-personal communication, through extension workers, friends, and family members, can influence behaviour and facilitate the transfer of ideas. The mass communication channels seldom affect decisions directly, although they operate through an intervening variable to influence behaviour. The information sources from outside the community (normally referred to as cosmopolitan) are most important at the awareness stage, and the local information sources from inside the community are the most important at the evaluation stage.

While some factors stimulate and facilitate quick diffusion of innovations and transfer of technologies, some others inhibit adoption. One of the hurdles to change is cultural incompatibility. Certain social systems do not encourage the adoption of innovations. Individuals in such a system are very slow and rigid in accepting new ideas, practices and technologies. The rice-eating people show marked resistance to accepting coarse grain since it involves a change in food habits. Many studies have substantiated that new crop varieties, which give higher yields and better incomes, have been rejected on the ground of taste, fear of ill-health, and unacceptability as food. Thus, cultural incompatibility and mismatch with the existing social system, which is considered to be very strong inhibiting factors in the process of diffusion of innovations. Other important factors identified in this context are (1) relative advantage of the innovation, (2) perceived impact of the adoption on social relations, (3) scope for reversibility in case the innovation is to be rejected, (4) complexities involved in the acceptance of the innovation on a sustainable basis. The simpler the innovation the higher is the scope for adoption.

Basing on the rate of adoption and the time lag between initial exposure to final adoption. diffusion researchers have classified adopters into five distinct categories: (1) venturesome innovators, (2) early adopters, (3) early majority, (4) late majority, and (5) laggards. The venturesome innovators are the most eager members of society to try new ideas and adopt new practices. They are enterprising and willing to take risks. Usually, they belong to the cosmopolite category. The early adopters, on the other hand, belong to the local system; they follow the venturesome. The innovators, becoming the reference pups for the subsequent late adopters, constitute the early majority and late majority. The laggards are very slow in adoption. They are rigid and hard to be convinced, stick to the old methods, and resist change.