AP® Human Geography review sheet from Aim for Five (aimforfive.com/geo/units/3/3-4)
Unit 3 · Topic 3.4
3.4 Types of Diffusion
Diffusion is how culture spreads from where it began. There are two main types, relocation and expansion, and expansion comes in three forms: contagious, hierarchical and stimulus.
Key terms
- cultural hearth
- relocation diffusion
- expansion diffusion
- contagious diffusion
- hierarchical diffusion
- stimulus diffusion
Hearths
A cultural hearth is the place where a culture trait, idea or innovation began. Hearths can be ancient, like the river valleys where farming and early cities started, or recent, like the Bronx in New York City, where hip-hop began in the 1970s. Diffusion is the spread of that trait outward from its hearth.
Relocation diffusion
Relocation diffusion happens when people move and take their culture with them to a new place. The trait doesn't necessarily grow stronger at home. Irish immigrants brought Catholicism and St. Patrick's Day parades to Boston and New York. Chinese immigrants brought their food and festivals to cities around the world. Spanish colonists brought Spanish to the Americas.
Relocation can jump long distances in one step, because the trait travels with the migrants. That's why you can find a Sikh gurdwara in Surrey, British Columbia, or a Lebanese restaurant in São Paulo, far from the hearth. Many traits spread by more than one type over time: a religion may arrive by relocation with settlers and then spread by expansion as neighbors convert.
Expansion diffusion
Expansion diffusion happens when a trait spreads outward from its hearth while staying strong, or growing, at the hearth. It's like a snowball. There are three kinds.
| Type | How it spreads | Example |
|---|---|---|
| Contagious | Person to person to nearby people, without regard to status, like a contagious disease | A dance trend spreading through social media; a virus spreading through a city |
| Hierarchical | From people or places with power, wealth or influence down to others, or from big cities to smaller ones | Fashion moving from Paris or New York to smaller cities; Christianity spreading after Roman emperors adopted it in the 300s |
| Stimulus | The basic idea spreads, but people change it to fit their own culture | McDonald's in India serves no beef and offers items like the potato-based McAloo Tikki; Sequoyah created a Cherokee writing system in the 1820s, inspired by the idea of English writing |
What speeds or slows diffusion
- Distance decay: traits usually spread to nearby places first (topic 1.4).
- Time-space compression and the internet: ideas now jump between distant cities almost instantly, so hierarchical and contagious diffusion happen at the same time.
- Barriers: physical barriers like mountains and oceans, and cultural barriers like religious rules, language differences or government censorship, can slow or block a trait.
- Some teachers mention reverse hierarchical diffusion, where a trait starts with less powerful groups or small places and moves up. It isn't in the course framework, so focus on the three main types.
Worked examples
Try each one yourself first, then open the solution.
- Example 1
Classifying a diffusion scenario
A clothing style appears first in a few global fashion capitals, then in large regional cities, and only later in small towns. Identify the type of diffusion and explain.
Show the solutionHide the solution
- Step 1: Notice the order: big, influential cities first, then smaller places.
- Step 2: Match the pattern: spread through a ranked order of places is hierarchical diffusion, a form of expansion diffusion.
- Step 3: Rule out the others: it isn't relocation (no one moved), not contagious (it skipped nearby small towns at first), and not stimulus (the style didn't change).
Answer: Hierarchical (expansion) diffusion, because the style moved down a ranking of places, from the most influential cities to smaller ones.
Common mistakes
- Calling something relocation diffusion when no one moved. If people stayed put and the idea traveled, it's expansion.
- Describing stimulus diffusion as any spread. The key is that the original idea is adapted, not copied.
- Treating contagious and hierarchical as opposites that never overlap. A trend can spread hierarchically to cities and then contagiously within them.
On the exam
- Classifying diffusion is one of the most common multiple-choice tasks in Unit 3; look for who moved, how the trait spread and whether it changed.
- In free response, explain the specific spread in the scenario, not just the definition.
Connected topics
Videos
Check yourself
4 questions on 3.4 Types of Diffusion. Pick an answer to see if you got it, and why.
Irish immigrants who settled in Boston in the 1800s brought Catholic churches, schools and festivals such as St. Patrick's Day celebrations with them. This is an example of
A new clothing style first appears in shows in Paris, Milan and New York, then in shops in other large cities, and only later in stores in small towns. This pattern is best described as
In the early 1800s, Sequoyah, a Cherokee man, saw that English speakers used written symbols to record their language. He did not adopt the English alphabet. Instead, he created a new writing system with a symbol for each syllable in Cherokee. This is an example of
A new dance first posted by a teenager in one town is copied by her friends, then by their friends in nearby towns, and soon by people of all ages across the region. This pattern is best described as
0 of 4 answered