Error and attack tolerance of collective problem solving: The DARPA Shredder Challenge

N. Stefanovitch, A. Alshamsi, M. Cebrian, I. Rahwan


The Internet has unleashed the capacity for planetary-scale collective problem solving (also known as crowdsourcing), with ever increasing successful examples. A key hypothesis behind crowdsourcing is that, at a critical mass of participation, it has the capacity not only to agglomerate and coordinate individual contributions from thousands of individuals, but also to filter out erroneous contributions, and even malicious behavior. Mixed evidence on this front has arisen from limited observational data and controlled laboratory experiments with problems of moderate difficulty. We analyze behavioral data from our participation in the DARPA Shredder Challenge, an NP-hard combinatorial puzzle beyond computational reach, which involved 3,500 participants from five continents over three consecutive weeks. We study thousands of erroneous contributions and a number of large-scale attacks, and quantify the extent to which the crowd was able to detect, react, and recover from them. Whereas the crowd is able to self-organize to recover from errors, we observe that participants are (i) unable to contain malicious behavior (attacks) and (ii) the attacks displayed persistence over the subsequent participants, manifested in decreased participation and reduced problem solving efficiency. Our results raise caution in the application of crowdsourced problem solving for sensitive tasks involving Financial Markets and National Security.

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