Spatial diffusion – ideas, innovations and disease
GeographyPopulation & SettlementAges 16–17
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Sign in to playIn a fictional region with a capital, cities, towns and villages, choose what spreads (an innovation, an idea or an infectious disease), where it starts and the type of diffusion: contagious, hierarchical, relocation or stimulus. Distance decay, the number of contacts per person and a mountain range, river or border change how fast and where it spreads; a step-by-step map, the S-shaped adoption curve and a scatter of adoption time against distance or settlement size let you compare the patterns.
Lesson: Spatial diffusion: contagious, hierarchical, relocation and stimulus diffusion, distance decay, barriers and the Hägerstrand model
What it shows
Spatial diffusion is the spread of something – an idea, an innovation, a religion or a disease – from its place of origin, or hearth, across space. Geographers distinguish expansion diffusion (contagious, hierarchical and stimulus), where the phenomenon spreads while staying at the hearth, from relocation diffusion, where people carry it to new places. This simulation follows Torsten Hägerstrand's Monte Carlo model: in each time step, every adopter contacts other people chosen at random, with nearby and larger places more likely, so you can watch distance decay, barriers and the urban hierarchy shape the pattern.
How to use
Choose the Diffusion type, What spreads and the Place of origin. Set Distance decay β, Contacts per person, a Barrier and its Permeability. Press Play or +1 step, or drag across the adoption curve, to follow the map step by step. Change Scatter by to distance or population size, press New random seed to see chance at work, and press Add to table to compare runs.
Parameters you can change
- Diffusion type Contagious, Hierarchical, Relocation, Stimulus
- What spreads Innovation, Idea or trend, Infectious disease
- Place of origin (hearth) Capital, Eastern city, Town, Remote village
- Distance decay (exponent β) 0.5–3
- Contacts per person per step (speed of communication) 1–10
- Barrier None, Mountain range, Wide river, National border
- Permeability of the barrier 0–100 %
- Random seed 1–999
- Time step shown 0–40
- Scatter by Distance from the origin, Population size
Questions to explore
- Why can a distant city adopt an innovation before a village next to the capital in hierarchical diffusion?
- How do the map and the adoption curve change when a mountain range lets only 10 % of contacts through?
- For an infectious disease, about how many contacts per person are needed for an outbreak to spread instead of dying out?
