Diffusion. Contagious and Hierarchical Diffusion

Distributions are dynamic, changing frequently over time. Diffusion is the spread of a new product, idea, or object across space through time—a process that results in changes in distribution patterns and density (Figure 1-6).

Figure 1-6. The Process of Diffusion. By the late 1980s, more than half of the American states had instituted state-run lotteries. The spread of the lottery idea among the states represents an interesting example of the diffusion process. New Hampshire first adopted a lottery in 1964. Other Northeastern states soon followed suit, but lotteries were not established in the South or West until the 1980s

As an example of the diffusion process, consider new fashion trends. Many of the fashions worn by American college students originate in southern California. Through television, movies, and other communications media, students in other parts of the United States become aware of what Californians are wearing. In order to stay in fashion, they purchase and wear the new styles. Eventually, students throughout the United States adopt the new fashion trend. At that point, the fashion has diffused across the country and the distribution of people wearing the new style has expanded.

Two basic types of diffusion are relocation diffusion and expansion diffusion. Relocation diffusion is diffusion that results from the movement of people. The settlement of the east coast of North America by Anglo-Americans initiated the diffusion of European cultural practices across the Atlantic Ocean. As they relocated to what is now the United States and Canada, European born settlers brought with them their religious and political beliefs, languages, domestic animals, crafts, and tools. European civilization diffused across the Atlantic Ocean, displacing the culture of the indigenous Native American population.

Expansion diffusion, on the other hand, is diffusion that results from the adoption of innovations. The diffusion of new fashion trends from southern California is an example of expansion diffusion.

Expansion diffusion involves innovation, information, and choice. The person adopting an innovation chooses to do so following receipt of information about that innovation. Expansion diffusion depends on communication. Communication must take place between those aware of the innovation and those deciding whether to adopt it. In today's world, telecommunications and other modern technology allow for very rapid communication between places, as we saw in our discussion of time-space convergence. Diffusion has become less dependent on distance and more dependent on the receptivity of the potential adopter to the information.

Contagious and Hierarchical Diffusion. In some cases, expansion diffusion occurs primarily between people in direct face-to-face contact or between people located in adjacent places. Diffusion of this sort is known as contagious diffusion, by analogy with the spread of infectious diseases by direct contact. If you choose to purchase a new fashion after seeing friends and neighbors wearing it. the diffusion process is contagious (Figure 1-7).

Figure 1-7. The Contagious and Hierarchical Diffusion of an Innovation. Levi's jeans display patterns which represent both contagious and hierarchical diffusions scenarios. The adoption patterns which "ripple" from the west show a definite contagious pattern, while the dominance of the major urban centers can be used to represent a more hierarchical pattern. (#1) Levi Strauss began producing dyed canvas overalls in San Francisco in the 1850s.

Soon farmers, miners, ranchers, and railroadmen west of the Rockies began wearing Levi Strauss jeans. (#2) In the 1930s, Eastern tourists took this "cowboy look" back home, where New York fashion designers (#3) in the 1940s further popularized the jeans. By the 1950s (#4) the young movie stars and rock-and-roll idols of the day turned Levi's® jeans into a fashion statement that spread around the world

By contrast, many people purchase new fashions after observing them in newspapers and magazines or on television. Mass-communications media enable the spread of information about new innovations across long distances. Diffusion resulting from long-distance information flow is known as hierarchical diffusion. We call such diffusion hierarchical because it often occurs outward from innovation centers in large metropolitan areas to adopters in smaller cities and towns.

The spread of new motion pictures illustrates hierarchical diffusion. New movies tend to be released in major metropolitan areas before being shown in smaller cities and towns. Movie producers release their films in large cities first because the potential audiences are greater than in smaller ones. Eventually, successful movies diffuse to smaller communities.

The speed at which diffusion occurs can be affected by processes that encourage or retard communication between places. Barriers to diffusion prevent or restrict the spread of diffusion-promoting information. Traditionally, international boundaries served as barriers to diffusion. The circulation of many newspapers and magazines declines substantially across an international boundary. In recent years, however, the barrier effect of international boundaries has declined. The unification of the European economies may expedite diffusion of new innovations throughout Europe.

Language barriers also inhibit diffusion. As we will see in Chapter 4, communication depends on a common language. Communication between people living in places in which different languages are spoken may be restricted, inhibiting diffusion. For example, the diffusion of some innovations from English-speaking Canada to Quebec is retarded because the dominant language of Quebec is not English, but French.

Diffusion can also be restricted by laws and practices that discourage adoption. Many countries maintain laws prohibiting the importation of products from other countries. Other governments levy taxes on various products to discourage people from purchasing them. Some American political leaders have proposed that the United States levy import taxes on foreign-made automobiles, television sets, and other consumer goods. Such taxes would retard the diffusion of foreign-made products into the United States.