Crowdsourcing in Manhunts Can Work

The social news website Reddit was left red-faced last week after misidentifying suspects in the bombings at the Boston Marathon in Massachusetts, raising questions about whether crowdsourcing might do more harm than good in during a manhunt. But work by an international team of scientists suggests that crowdsourcing is a powerful tool in such situations, if used carefully.

Some social-networking enthusiasts contend that online tools such as Facebook or Reddit can harness the help of huge numbers of volunteers to assist in investigations. For example, photos of 'wanted' suspects can be spread rapidly among users on social networks. Critics point out, however, that by responding in haste or with misdirected zeal, users can make false accusations and point law-enforcement forces officers in the wrong direction, as seems to have happened in the Boston case.

Iyad Rahwan, a computer scientist at the Masdar Institute of Science and Technology in Abu Dhabi, and his colleagues showed last year that networks such as Twitter and Facebook can be harnessed to find individuals across the globe from just their photos. Now, in a preprint posted on the online repository arXiv.org, the researchers explain what made that experiment successful. They say that participants responded to the urgency of the search not by sending out messages in an indiscriminate, blind panic, but by becoming more focused and directed about whom they contacted.