Diffusion of innovations

By James W. Dearing

James W. Dearing (biography)

How—and why—do people decide to try new things?

Studies of diffusion have frequently demonstrated a mathematically consistent sigmoid pattern (the S-shaped curve, see figure below) of over-time adoption for innovations. Innovations include new beliefs, practices, programs, policies, and technologies.

The “S” shape is due to the positive engagement of informal opinion leaders in talking about and modeling an innovation for others to hear about and see. The initial slow rate of adoption gives way to a rapidly accelerating rate, which then slows as fewer non-adopters remain. Alternatively and more commonly, when informally influential people do not get positively engaged or when they ignore or actively reject an innovation, diffusion does not occur and the resulting slope of a cumulative curve stays flat or turns negative.

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