diffusion:
A process by which an innovation
spreads across space.
innovation: the phenomenon that
diffuses.
(This could be an idea, a disease,
an invention, a new style of fashion
or music, a language, a word, a
product, a religion, a food, news, a
sport...almost anything!)
hearth (aka node): the place from
which an innovation originates
and then diffuses.
Hearths require a culture group that has
1) the willingness,
2) the technical ability, and
3) the financial resources
to accept and nurture the innovation.
There are three cultural and economic hearths
in the world today: N. America, Europe, and
Japan. New York, London, and Tokyo are known
as economic command centers because
economic commands are issued from these
cities.
periphery: the place to which an
innovation spreads.
In general Asia, Africa, and Latin
America are peripheral in this
sense.
independent invention
(aka parallel invention):
when there are two or more
hearths without contact with each
other from which an innovation
originates
diffusion barrier: any factor that
slows down or blocks diffusion.
The most basic barrier to diffusion
is distance.
time-distance decay
(aka friction of distance):
the idea that the farther away a place is
from a hearth and the longer it takes an
innovation to reach its potential
adopters, the less likely the innovation
will be adopted.
For some (but not all) phenomena,
technology is making distance less of a
barrier to diffusion. This is called:
Space-Time Compression:
the reduction in the time it takes for
an innovation to diffuse due to
technology.
Space-Time
compression
Distances seem less remote. We know
what is going on elsewhere sooner.
Space-Time compression has
accelerated rapidly in recent years due
to affordable and widespread air travel,
internet, cell phones, etc.
Other types of diffusion barriers:
physical barriers: oceans, rivers, mountain,
deserts, walls, political borders.
cultural barriers (most important): language,
sexual mores, dietary restrictions, religious
taboos, long standing traditions.
economic barriers: Adopters cannot afford
innovation or see no economic benefit in it.
S-shape adoption curve: a graph
showing the rate at which an
innovation is typically adopted
in a population.
Laggards
Majority
Innovators
First stage: few adopters because innovation is not
widely known and because most of population is
risk averse (why not wait?)
Second stage: number of adopters grows
exponentially as word spreads and perceived risk
and price (if applicable) decrease. The majority of
all eventual adopters adopt in this stage.
Third stage: rate of adoption tapers off as there are
fewer people susceptible to adoption and novelty
wears off.
Types of Diffusion
Relocation
Contagious
Expansion
Hierarchical
Stimulus
Types of Diffusion
• Relocation- The spread of an idea through the
movement of people from one place to another.
• Expansion- when an innovation or idea develops in a
hearth and remains strong there while also spreading
outward through a snowball effect.
– Contagious- a form of expansion diffusion characterized by
a rapid widespread diffusion of a characteristic throughout
a population through direct person to person contact,
analogous to the spread of a disease
– Hierarchal- a form of expansion diffusion characterized by
the spread of an idea from powerful persons (political or
business leaders, social elites, or other important persons)
or from places of power (usually large cities) to other
persons or places, jumping over intervening areas.
– Stimulus- a form of expansion diffusion in which an
innovation is not adopted in its entirety but nevertheless
stimulates some experimentation) or imitative behavior in
the new community.
Expansion vs. Relocation Diffusion
H
Expansion Diffusion
Innovation stays strong at hearth
while expanding elsewhere.
H
Relocation Diffusion
Innovation is carried away from
hearth most often via migration
and may die out at hearth.
The wearing of turquoise jewelry has waves of popularity, but
remains strongest at its hearth in New Mexico and Arizona. Is
this an example expansion or relocation diffusion?
What type of diffusion brought Christianity to North America?
Contagious vs. Hierarchical Diffusion
(Both forms of expansion diffusion because the innovation can
spread while people stay in place.)
Contagious Diffusion
Hierarchical Diffusion
The innovation spreads outward
through direct person to person
contact. No jumping.
The innovation spreads from one
power node to another jumping
over intervening areas.
Classic wave pattern of contagious diffusion.
(Left: spread of agriculture from Middle East
into Europe. Right: spread of 1871 influenza
epidemic.)
By what type of diffusion was Christianity spread to Native
Americans?
To distinguish between contagious and hierarchical diffusion, ask yourself:
is this phenomenon spreading on the basis of proximity or rank?
Above: diffusion of fashion as a classic example of hierarchal diffusion.
The following slides show the
diffusion of the Euro coin in France
after its introduction in 2001.
What type of diffusion is
represented by these slides?
If you said the Euro spread through
France via contagious diffusion,
you would be suggesting that the
Euro spread through France in
what rather unlikely (and illegal)
fashion?
What type of diffusion is represented by the rapid spread of
Islam after the death of Mohammed in the 7th c.?
What type of diffusion is represented by the spread
of Hip Hop nationwide in the mid 1980’s?
What type of diffusion is represented by the
application of herding techniques by Siberian Inuit
after observing cattle herding to the South?
Another example of stimulus
diffusion: gang dress
adopted by suburban white
kids even though they reject
the life style that spawned
this fashion.
In the real world, all types of
diffusion are at work
simultaneously. In particular it is
often difficult to untangle
contagious and hierarchical
diffusion. In many cases,
innovations spread first by
hierarchical diffusion and then by
contagious diffusion, which is
usually the final stage.
Christianity
spread throughout
Europe first
hierarchically to
the major power
centers in the
Roman Empire,
and then
contagiously to
smaller towns and
rural areas.
The AIDS virus
spread first
hierarchically,
jumping to
cities with high
populations of
gay men and
intravenous
drug users, and
then
contagiously
among those
populations.
The HIV drugs
diffused
following a
similar pattern.
The H1N1 virus spread first spread person to person (contagiously)
in Mexico, then was brought to NYC by kids vacationing in Mexico
(relocation) then spread in NYC (contagious) before jumping to cities
all over the U.S. and around the world (relocation).
What type of diffusion best
describes the diffusion of Walmart
stores depicted in the following
video?