1. General Principles of Diffusion

2. Diffusion – A Definition Diffusion is the process of spread in geographic space and growth through time of an innovation, idea or piece of information.

3. General Rule The rate of diffusion through an area of space is directly influenced by the distance from the source area and the available infrastructure.

4. Factors that Influence Diffusion Resistance Neighborhood Effect

5. Resistance Acceptance of an idea, innovation or new information is not automatic. If the innovation is resisted, this will decrease the rate of adoption and diffusion. Urban dwellers are less resistant to new information than rural dwellers. Resistance is highly influenced by both culture and economics.

6. Neighborhood Effect An innovation will be more likely to be adopted first close to its source area and then later at greater distances.

7. Types of Diffusion Wave Hierarchical Relocation Contagious

8. Wave Diffusion Wave diffusion is most closely associated with the neighborhood effect. In this form of diffusion an innovation, idea or piece of information emanates from a single source area and radiates outward with decreasing intensity as distance increases from the source area. The effect is similar to the ripple effect produced when you throw a stone into a pond.

9. Hierarchical Diffusion Occurs when an innovation or idea moves through the urban hierarchy both horizontally and vertically. The innovation originates in the largest city, passing through its surrounding towns first (horizontal movement) and then proceeds down the hierarchy vertically to the next largest city and its surrounding towns and so on until the innovation has saturated the hierarchy.

10. General Rule The rate of diffusion within the urban hierarchy is directly related to the density of the infrastructure connecting the cities and towns within the hierarchy.

11. Relocation Diffusion Occurs when an individual or group comes into a new area and brings with them new ideas and innovations which then may spread through a region as result of wave, hierarchical, or contagious diffusion. Through relocation diffusion, innovations appear to “jump” across large distances

12. Contagious Diffusion Occurs when an idea, innovation, piece of information, or disease, spreads as a result of one-to-one contact. Contagious diffusion may be aided by both relocation and hierarchical diffusion.