Diffusion and Adoption of Innovations

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Diffusion is the process by which an innovation is communicated through certain channels, over time, among the members of a social system. It is a special type of communication concerned with the spread of messages that are perceived as new ideas and which will necessarily be received with some degree of uncertainty. The four main elements in the diffusion of new ideas are: (1) innovation, (2) communication channels, (3) time, and (4) the social system.


An innovation is an idea, practice, or object that is perceived as new. The characteristics of an innovation, as perceived by members of a social system, determine its rate of adoption. Some innovations diffuse relatively slowly, while other innovations diffuse rapidly. The characteristics that determine an innovation's rate of adoption are its relative advantage, compatibility, complexity, trialability, and observability.

The relative advantage of an innovation reflects the degree to which it is perceived as better than the idea it supercedes. The degree of relative advantage may be measured in economic terms, but social prestige, convenience, and satisfaction are also important factors. It does not matter so much if an innovation has a great deal of objective advantage. What does matter is whether individuals perceive the innovation as advantageous. The greater the perceived relative advantage of an innovation, the more rapid its rate of adoption will be.

Compatibility is the degree to which an innovation is perceived as being consistent with the existing values, past experiences, and needs of potential uses. An idea that is incompatible with the values and norms of a social system will not be adopted as rapidly as an innovation that is compatible. The adoption of an incompatible innovation often requires the prior adoption of a new value system, which is a relatively slow process. Technological compatibility may be involved in cases where a particular software program cannot be used because it will not work with a computer's operation system.

Complexity refers to the degree to which an innovation is perceived as difficult to understand and use. Some innovations are readily understood by most members of a social system; others are more complicated and will be adopted more slowly. New ideas that are simpler to understand are adopted more rapidly than innovations that require people to develop new skills and understandings.

Trialability is the degree to which an innovation may be experimented with on a limited basis. New ideas that can be tried on an installment plan will generally be adopted more quickly than innovations that are not divisible. An innovation that is trialable represents less uncertainty to the individual considering using it and who can learn by doing.

Observability is the degree to which the results of an innovation are visible. The easier it is for individuals to see the results of an innovation, the more likely they are to adopt it. Such visibility stimulates peer discussion of a new idea, as friends and neighbors of a user of a product often request information about it.

Overall, innovations that are perceived by individuals as having greater relative advantage, compatibility, trialability, and observability, and as less complex, will be adopted more rapidly than other innovations.


The second main element in the diffusion of new ideas is the communication channel. Communication is the process by which participants create and share information with one another to reach a mutual understanding. A communication channel is the means by which messages get from one individual to another. Mass media channels are more effective in creating knowledge of innovations, whereas interpersonal channels are more effective in forming and changing attitudes toward a new idea, and thus in influencing the decision to adopt or reject a new idea.

Most individuals evaluate an innovation, not on the basis of scientific research by experts, but through the subjective evaluations of peers who have adopted the innovation. So the diffusion process is essentially social in nature, driven by individuals talking to others and giving meaning to an innovation through a process of social construction.


The third element in the diffusion of new ideas is time. The time dimension is involved in three ways.

First, time is involved in the innovation-decision process. This is the mental process through which an individual (or other decision-making unit) passes from first knowledge of an innovation to forming an attitude toward the innovation; then to a decision to adopt or reject it; then to implementation of the new idea; and finally to confirmation of the decision to adopt the innovation. An individual seeks information at various stages in the innovation-decision process in order to decrease uncertainty about an innovation's expected consequences.

The second way in which time is involved in diffusion is in the innovativeness of an individual or other unit of adoption. Innovativeness is the degree to which an individual or other unit of adoption is relatively earlier in adopting the new ideas than other members of a social system. There are five adopter categories, or classifications of the members of a social system on the basis of their innovativeness. These categories are: (1) innovators, (2) early adopters, (3) early majority, (4) late majority, and (5) laggards.

Innovators are defined as the first 2.5 percent of the individuals in a system to adopt an innovation. Venturesomeness is almost an obsession with innovators. This interest in new ideas leads them out of a local circle of peer networks and into more cosmopolitan social relationships. Control of substantial financial resources is helpful to absorb possible losses from an unprofitable innovation. The ability to understand and apply complex technical knowledge is also needed. The innovator must be able to cope with a high degree of uncertainty about an innovation at the time of adoption. While an innovator may not always be respected by the other members of a social system, the innovator plays an important role in the diffusion process.

Early adopters are the next 13.5 percent of the individuals in a system to adopt an innovation. Early adopters are a more integrated part of a social system than are innovators. Whereas innovators are cosmopolites, early adopters are localites. This adopter category, more than any other, has the greatest degree of opinion leadership in most systems. Potential adopters look to early adopters for advice and information about an innovation. Early adopters are the embodiment of the successful use of new ideas, and they know that to continue to earn the esteem of colleagues and to maintain a central position as an opinion leader they must make judicious innovation decisions.

The early majority category contains the next 34 percent of individuals in a system to adopt an innovation. The early majority adopt new ideas just before the average member of a system. They interact frequently with their peers, but seldom hold positions of opinion leadership in a system. The early majority's unique position between the very early and the relatively late to adopt makes them an important link in the diffusion process.

The late majority is the next 34 percent of the individuals in a system to adopt an innovation. The late majority adopt new ideas just after the average member of a system. Like the early majority, the late majority make up one-third of the members of a system. Adoption may be the result of increasing network pressures from peers. Innovations are approached with a skeptical and cautious air, and the late majority do not adopt until most others in their system have done so. The weight of system norms must definitely favor an innovation before the late majority are convinced. The pressure of peers is necessary to motivate adoption.

Laggards are the last 16 percent of the individuals in a system to adopt an innovation. They possess almost no opinion leadership. Laggards are the most local in their outlook of all adopter categories; many are near isolates in the social networks of their system.

The third dimension in which time is involved in diffusion is in rate of adoption. This is the relative speed with which an innovation is adopted by members of a social system. The rate of adoption is usually measured as the number of members of the system that adopt the innovation in a given time period.


The fourth main element in the diffusion of new ideas is the social system. A social system is defined as a set of interrelated units that are engaged in joint problem solving to accomplish common goals. The members or units of a social system may be individuals, informal groups, organizations, and/or subsystems. The social system constitutes a boundary within which an innovation diffuses. Diffusion is affected by norms, which are the established behavior patterns for the members of a social system, and by opinion leadership, which is the degree to which an individual is able to influence the attitudes or overt behavior of other individuals in a desired way with relative frequency.

A key concept in understanding the nature of the diffusion process is the critical mass, which occurs at the point at which enough individuals have adopted an innovation so that the innovation's further rate of adoption becomes self-sustaining. The concept of the critical mass implies that outreach activities should be concentrated on getting the use of the innovation to the point of critical mass. These efforts should be focused on the early adopters, who are often opinion leaders and serve as role models for many other members of the social system. Early adopters are instrumental in getting an innovation to the point of critical mass, and, therefore, they are instrumental in the successful diffusion and adoption of an innovation.

Everett M. Rogers

(see also: Communication for Health; Communication Theory; Diffusion Theory; Health Promotion and Education; Social Cognitive Theory; Social Networks and Social Support; Sociology in Public Health; Transtheoretical Model of Stages of Change )


Rogers, E. M. (1995). Diffusion of Innovations, 4th edition. New York: Free Press.