#171 from R&D
Innovator Volume 4, Number 8
Creative Spark for Invention
Dr. Holyoak is professor of psychology at the University of California, Los Angeles, and Paul Thagard is professor of philosophy at the University of Waterloo, Canada. They have collaborated for many years in studying the use of analogy--reasoning from past cases to new problems--in applications ranging from everyday problem solving to scientific discovery. This article is based on their book Mental Leaps: Analogy in Creative Thought (MIT Press, Cambridge, 1995).
The launch of the
Hubble Space Telescope in 1990, heralded as a triumph for the
beleaguered NASA, quickly became a high-flying embarrassment when
the telescope's would-be users realized that its mirror had been
ground improperly. The
most powerful eye on the universe turned out to have blurry
vision, and a fix was desperately needed.
Where did the
idea for a solution originate?
In the shower of a German hotel room, when a soggy NASA
engineer James Crocker was looking at a shower head that could be
extended to adjust to the user's height.
Crocker made an analogy between this plumbing fixture and
the myopic telescope, and invented the idea of placing corrective
mirrors on automated arms that would reach inside the telescope
and adjust to the correct position.
device, COSTAR (corrective optics space telescope axial
replacement), was considerably more complex than a shower head. It consisted of eight motors attached to five metal arms
holding ten coin-sized mirrors.
In 1994, NASA used COSTAR to turn Hubble from a debacle
into a triumph, after a space shuttle mission installed the
corrective lenses with millionths-of-an-inch precision into a
seemingly inaccessible part of the space observatory, while Hubble
orbited 300 miles above earth.
The leap from an
adjustable shower head to a corrective lens is only a recent
example of a creative process that has often sparked major
advances in science and technology.
Historians, philosophers, and psychologists of science have
documented many instances of analogical thinking.
recorded use of analogy in a landmark scientific theory dates back
at least 2,000 years, to the recognition that sound is propagated
as waves. A Roman
architect and engineer, Vitruvius, noticed several important
similarities in the behavior of sound and water waves, such as the
parallels between echoes and the rebound of water waves after
striking an obstacle. In
modern jargon, the water waves provided the familiar source
analog, which Vitruvius used to understand the unfamiliar target
analog, the nature of sound.
This mental leap was eventually followed in the seventeenth
century by another giant advance--a new analogy drawn between
sound and light, which led to the wave theory of light.
Since science is
the foundation for technology and engineering, it’s not
surprising that analogies have contributed to new inventions, of
which COSTAR is neither the first nor the most significant.
For example, when Alexander Graham Bell was inventing the
telephone, he explicitly used an analogy to nature:
"Make transmitting instrument after the model of the
human ear. Make
armature the shape of the ossicles.
Follow out the analogy of nature."
He drew diagrams that made explicit the structure of the
ear and then drew analogous diagrams of physical devices that
could transmit vibrations in a similar manner.
His analogy thus employed visual as well as verbal
technological breakthrough based on a visual analogy to nature is
the Velcro fastener. In
1948, George deMestral noticed that burdock burrs stuck to his
dog's fur with tiny hooks. He figured out how to produce the same effect artificially,
and now shoes and countless other objects are fastened with
burr-like hooks and cloth-like loops.
telephone, Velcro was a technology that drew on a natural analog,
but in this case the technology was later used as a source analog.
Thus the hook-loop concept led to discoveries such as
abdominal closure in surgery, epidermal structure, molecular
bonding, antigen recognition, and hydrogen bonding.
biological analogs may fail, especially when they are shallow
(remember Icarus' vain attempt to glue feathers to his arms to
emulate a bird's wings?). Or sometimes they may be partly successful:
obviously, the Wright brothers used aerodynamic principles
of lift and drag, rather than use the flapping of wings to produce
lift in the first working airplane.
Nevertheless, they did use an analogy with birds: when
Wilbur Wright noticed that soaring birds twist their wings to
restore balance, he warped the wings of the aircraft to achieve
the same effect.
the Mental Leap
To propose an
analogy, or simply to understand one, we must take a kind of
mental leap. Like a spark that jumps across a gap, an idea from the source
analog is carried over to the target.
The two analogs may initially seem unrelated, but the act
of making an analogy creates connections between them.
Nothing guarantees that the target will behave the way the
source suggests it might. Some
analogical mental leaps have ended in creative triumph, such as
the wave theories of sound and light, and the invention of the
telephone; others have ended in dismal failures.
an analogy requires a leap, that leap need not be blind or random.
Recent work in cognitive science indicates that reasoning
by analogy is guided by a few cognitive constraints, including
these three basic types:
finding correspondences based on shared structure.
Sound waves and water waves, for example, share such
structural properties as rebounding after striking a barrier, and
diminishing in intensity with distance from their origin.
mapping elements that are directly similar.
This is why it seemed so natural to model airplane wings on
bird wings--both are immediately recognized as belonging to the
identifying correspondences that will achieve their purpose
in using the analogy. The
engineer who jumped from the adjustable shower to the near-sighted
telescope focused on how the shower's height could be continuously
adjusted (rather than, say, the temperature of the water it
emitted) because height adjustability was relevant to his problem.
The use of good
analogies can be advanced by social means, and research groups
that foster analogies can gain a creative edge.
Kevin Dunbar has described (in Mechanisms of Insight,
MIT Press, 1994, Cambridge, MA; R.J. Sternberg and J. Davidson,
eds.) how the social structure of laboratories can greatly affect
the use of scientific analogies. In labs where researchers have diverse training, productive
analogies frequently emerge in meetings.
A target problem that has stumped one researcher can be
approached with a source analogy from another researcher with a
different background. Like
broader human culture, science and technology are products of
social interaction and individual cognition.
that analogy provides plausible conjectures, not infallible
generated by analogy must always be tested to see if they’re
actually helpful. But
when done carefully, thinking by analogy tends to produce ideas
that are worth considering, even if they ultimately prove flawed.