THE FIRST EDITION OF THIS BOOK, Diffusion of Innovations, was

published in 1962. At the time, there were 405 publications about this

topic available. The second edition and revision, Communication of

Innovations: A Cross-Cultural Approach (co-authored with F. Floyd

Shoemaker), was published in 1971, nine years later. By then the

number of diffusion publications had almost quadrupled to about

1,500, of which approximately 1,200 were empirical research reports,

and the other 300 were bibliographies, syntheses, theoretical writings,

and other types of nonempirical publications.

At present, 12 years later, the total number of diffusion publications

has more than doubled again, to 3,085. And the number of empirical

diffusion research reports has increased from 1,500 to 2,297. I

think there is almost no other field of behavior science research that

represents more effort by more scholars in more nations.

Because of this vast increase in the foundation of diffusion

research on which the present book is based, it is both (1) a revision of

the theoretical framework, and the research evidence supporting this

model of diffusion, and (2) a new intellectual venture, in the sense that

new concepts and new theoretical viewpoints are introduced. I

estimate that this book represents about equally (1) a continuity with

my two previous books on diffusion, and (2) differences and improvements

in the basic framework. So the reader can regard the present

book as the third volume in a three-volume set on the diffusion of

innovations. The stream of diffusion scholarship over the past forty

years or so represents both similarities and differences, continuities

and discontinuities, and so must my three books, each published approximately

a decade apart. By no means, however, do I seek only to

synthesize the important findings from past research; I also strive

herein to criticize this work (including my own), and to lay out directions

for the future that are different from the recent past.

I have titled the present book Diffusion of Innovations to identifyit 

with the forty-year sequential tradition of diffusion studies marked

by my 1962 book of the same title. In any event, most people refer to

this research field and its applications as the "diffusion of innovations."

By choosing a title somewhat different from my second book,

I can help avoid confusion of these two volumes.

Most diffusion studies prior to 1962 were conducted in the United

States and Europe. In the period between the first and second editions

of my diffusion book, during the 1960s, an explosion occurred in the

number of diffusion investigations that were conducted in the developing

nations of Latin America, Africa, and Asia. It was realized that

the classical diffusion model could be usefully applied to the process

of socioeconomic development. In fact, the diffusion approach was a

natural framework in which to evaluate the impact of development

programs in agriculture, family planning, public health, and nutrition.

But in studying the diffusion of innovations in developing nations,

we gradually realized that certain limitations existed in the diffusion

framework. In some cases, development programs outran the

diffusion model on which they were originally based. One intellectual

outcome was certain modifications that have been made in the classical

diffusion model. As a result, the diffusion paradigm that is

presented in this book is less culture-bound than in my previous

books. And the study of diffusion has today become worldwide.

During the 1970s, I have also seen important changes, modifications,

and improvements made in the diffusion model in the United

States and other industrialized nations. One important type of change

has been to view the diffusion process in a wider scope and to understand

that diffusion is one part of a larger process which begins with a

perceived problem or need, through research and development on a

possible solution, the decision by a change agency that this innovation

should be diffused, and then its diffusion (leading to certain consequences).

Such a broader view of the innovation-development process

recognizes that many decisions and activities must happen before the

beginning of the diffusion of an innovation; often diffusion cannot be

very completely understood if these previous phases of the total process

are ignored. Chapter 4 of the present book deals with this issue of

where innovations come from, and how their origins affect their diffusion.

Another important intellectual change of the past decade, reflected

in Chapter 10, is the greatly increased interest in the innovation

process in organizations. Such organizational decisions are different

in important ways from innovation decisions by individuals, we now

realize.

The present book also differs from its two predecessors in that it

reflects a much more critical stance. During the past twenty years or

so, diffusion research has grown to be widely recognized, applied, and

admired, but it has also been subjected to constructive and destructive

criticism. This criticism is due in large part to the stereotyped and

limited ways in which most diffusion scholars have come to define the

scope and method of their field of study. Once diffusion researchers

came to represent an "invisible college,"* they began to limit unnecessarily

the ways in which they went about studying the diffusion of

innovations. Such standardization of approaches has, especially in the

past decade, begun to constrain the intellectual progress of diffusion

research.

Perhaps the diffusion case is rather similar to that of persuasion

research, another important sub field of communication research.

Two of the leading persuasion scholars, Professors Gerald R. Miller

and Michael Burgoon (1978, p. 31), recently described the myopic

view of the social-influence process held by most persuasion scholars:

"Students of persuasion may have fallen captive to the limits imposed

by their own operational definitions of the area" [sentence was italicized

in the original]. This self-criticism applies to diffusion researchers

as well, because, in fact, many diffusion scholars have conceptualized

the diffusion process as one-way persuasion. As such,

they also may be subject to the four shortcomings of persuasion

research listed by Miller and Burgoon (1978, pp. 31-35):

1. Persuasion (and diffusion) are seen as a linear, unidirectional

communication activity. An active source constructs messages in

order to influence the attitudes and/or behaviors of passive receivers.

Cause resides in the source, and effect in the receiver.

2. Persuasion (and diffusion) are considered as a one-to-many

communication activity. This view is inconsistent with more recent

conceptions of persuasion: "Persuasion is not something one person

does to another but something he or she does with another" (Reardon,

1981, p. 25).

3. Persuasion (and diffusion) scholars are preoccupied with an

action-centered and issue-centered communication activity, such as

selling products, actions, or policies. Largely ignored is the fact that

an important part of persuasion/diffusion is selling oneself and, perhaps,

other persons. It should be realized that one objective of certain

diffusion activities is to enhance one's personal credibility in the eyes

of others (as we detail in Chapters 8 and 9).

An invisible college is an informal network of researchers who form around an intellectual

paradigm to study a common topic (Price, 1963; Kuhn, 1970; Crane, 1972).

4. Persuasion (and diffusion) researchers often give allegiance to

the view that their dependent variable is to change attitudes rather

than overt behavior. Diffusion researchers have been more oriented to

the dependent variable of adoption (a decision to use and implement a

new idea), than to actual implementation itself (or to studying the consequences

of innovation).

Most past diffusion studies have been based upon a linear model

of communication, defined as the process by which messages are

transferred from a source to a receiver. Such a one-way view of human

communication describes certain types of communication; many

kinds of diffusion do indeed consist of one individual, such as a

change agent, informing a potential adopter about a new idea. But

other types of diffusion are more accurately described by a convergence

model, in which communication is defined as a process in

which the participants create and share information with one another

to reach a mutual understanding (Rogers and Kincaid, 1981, p. 63).

In the present book we seek to show the improved understanding

that can often be achieved by conceptualizing certain kinds of diffusion

in light of this convergence model. This emphasis on diffusion as

information exchange among participants in a communication process

is found particularly in our Chapter 8 on diffusion networks.

Conceptually, the present book makes use of the important concepts

of uncertainty and information. Uncertainty is the degree to

which a number of alternatives are perceived with respect to the occurrence

of an event and the relative probabilities of these alternatives.

Uncertainty implies a lack of predictability of the future. It motivates

an individual to seek information. Information is a difference in

matter-energy that affects uncertainty in a situation where a choice exists

among a set of alternatives (Rogers and Kincaid, 1981, p. 64). The

concept of information is a favorite in the field of communication

research, and in fact the field really began to grow as an intellectual

enterprise once Claude Shannon and Warren Weaver (1949) had proposed

a theory of communication that was organized around the notion

of information.

One kind of uncertainty is generated by an innovation, defined as

an idea, practice, or object that is perceived as new by an individual or

another unit of adoption. An innovation presents an individual or an

organization with a new alternative or alternatives, with new means of

solving problems. But the probabilities of the new alternatives being

superior to previous practice are not exactly known by the individual

problem solvers. Thus, they are motivated to seek further information

about the innovation in order to cope with the uncertainty that it

creates.

So the present book is cast in a theoretical framework involving

the concepts of information and uncertainty. Information about innovations

is often sought from near-peers, especially information

about their subjective evaluations of the innovation. This information

exchange about a new idea occurs through a convergence process involving

interpersonal networks. The diffusion of innovations, thus, is

essentially a social process in which subjectively perceived information

about a new idea is communicated.

The general field of communication research has not been characterized

by much "weed pulling," that is, the criticism of our scientific

activities so that the field's findings and fallacies can be publicly

understood (Siebold, 1979). Thus, it may be a healthy turn of events

that, beginning in the early 1970s, criticisms of the diffusion framework

began to appear. Of course, it would be a mistake to become so

fond of weed pulling that the entire garden is destroyed (Reardon,

1981, p. 261).

Throughout the present book we seek to represent a healthily critical

stance. We do not just need more-of-the-same diffusion research.

The challenge for diffusion scholars of the future is to move beyond

the proven methods and models of the past, to recognize their shortcomings

and limitations, and to broaden their conceptions of the diffusion

of innovations. We offer this book as one step toward this goal.

Stanford, California Everett M. Rogers