Faculty Candidate Seminar

Human Computation

Dr. Luis von Ahn

Dr. von Ahn is a Post-Doctoral Fellow at Carnegie Mellon University
Tasks like image recognition are trivial for humans, but continue to
challenge even the most sophisticated computer programs. This talk
introduces a paradigm for utilizing human processing power to solve
problems that computers cannot yet solve. Traditional approaches to
solving such problems focus on improving software. I advocate a novel
approach: constructively channel human brainpower using computer
games. For example, the ESP Game, described in this talk, is an
enjoyable online game — many people play over 40 hours a week — and
when people play, they help label images on the Web with descriptive
keywords. These keywords can be used to significantly improve the
accuracy of image search. People play the game not because they want
to help, but because they enjoy it. The ESP Game has been licensed by
a major Internet company and will soon become the basis of their image
search engine.

I describe other examples of "games with a purpose" : Peekaboom, which
helps determine the location of objects in images, and Verbosity,
which collects common-sense knowledge. I also explain a general
approach for constructing games with a purpose.

In addition, I describe my work on CAPTCHAs, automated tests
that humans can pass but computer programs cannot. CAPTCHAs take
advantage of human processing power in order to differentiate humans
from computers, an ability that has important applications in

The results of this work are currently in use by hundreds of Web sites
and companies around the world, and over 100,000 people have played
some of the games presented here. Practical applications
include improvements in areas such as: computer vision, image search,
adult-content filtering, spam prevention, common-sense reasoning,
accessibility, and security in general.
Luis von Ahn is a Post-Doctoral Fellow in the Computer Science
Department at Carnegie Mellon University, where he also received his
Ph.D. in 2005. Previously, Luis obtained a B.S. in mathematics from
Duke University in 2000. He is the recipient of a Microsoft Research
Fellowship. His research interests include encouraging people to do
work for free, as well as catching and thwarting cheaters in online
environments. His work has appeared in over 100 news outlets including
The New York Times, CNN, USA Today, The BBC, and The Discovery
Channel. Luis holds 4 patent applications, and has licensed technology
to major Internet companies.

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