Geography Terms: Diffusion

USA, New York, Manhattan, Times Square, illuminated billboards, night
 Hisham Ibrahim/Getty Images

Diffusion, in the scope of geography, is the spread of people, things, ideas, cultural practices, disease, technology, weather, and more from place to place; thus, it's called spatial diffusion. Several types of it exist: expansion (contagious and hierarchal), stimulus, and relocation diffusion. 

Spatial

Globalization is an example of spatial diffusion. Take, for example, products in a person's home. A woman's handbag may have been made in France, her computer in China. Her spouse's shoes may have come from Italy and car from Germany. Spatial diffusion has a clear origin point that it spreads from. How quickly and through what channels is spreads determine its class or category.

Contagious and Hierarchal Expansion

Expansion diffusion comes in two types, contagious and heirarchal. In the first, a contagious disease is a prime example. It knows no rules or boundaries as to where it spreads. A forest fire could also fall under this category. In social media, memes and viral videos spread from person to person in contagious expansion diffusion as they are shared. It's no coincidence that something that spreads quickly and widely on social media is deemed "going viral." Religions spread through contagious diffusion as well, as people need to come in contact with the beliefs somehow to learn about them and adopt them.

Heirarchal diffusion follows a chain of command, for example, in business or different levels of government. The CEO of a company or the leader of a government body would likely know information before it is disseminated among a wide employee base or the general public.

Fads and trends that start with one community before spreading to the wider public also can be heirarchal, such as hip-hop music starting in urban centers or slang words starting with one particular age group before wider adoption—and then actually making it into the dictionary.

Stimulus

In stimulus diffusion, a trend catches on but is changed as it is adopted by different groups, such as when a religion is adopted by a population but the practices are blended with the existing culture's customs.

Stimulus diffusion can also apply to the more mundane as well. "Cat yoga," an exercise fad in the United States, is much different than the traditional meditative practice, for example. The varied menus of McDonald's restaurants around the world resemble the original menus but have been adapted to local tastes and religious food practices to be distinct.

Relocation

In relocation diffusion, whatever changes place leaves behind its point of origin. The concept can be simply illustrated through the immigration of people from place to place or even the movement of people from the countryside to the city. In the case of people immigrating, their cultral traditions and practices are then shared with their new community and maybe even adopted. Relocation diffusion can happen in the business community as well, as new employees come to a company with good ideas from their previous workplaces.

Relocation diffusion can also be illustrated with the movement of air masses that spawn storms as they spread across a landscape.