The concept of "general intelligence"—the idea that people who are good at one mental task tend to be good at many others—was considered radical in 1904, when Charles Spearman proposed the theory of a "g factor." Today, however, it is among the most replicated findings in psychology. But whereas in 1904 the U.S. economy was a network of farms, mills, and artisans, today's economy is an office-based affair, where the most important g for many companies doesn't stand for general intelligence, but, rather, groups.

So, what makes groups smart? Is there any such thing as a "smart" group, or are groups just, well, clumps of smart people?

As a team of scientists from MIT, Carnegie Mellon, and Union College write in this Sunday's New York Times, research suggests that just as some individuals are smarter than others, some groups are smarter than others, across a range of tests and tasks. In other words, there is a "c factor" for collective intelligence. Teams that are successful at solving visual puzzles also tend to be good at brainstorming and beating computers in video games. The authors provide a nice summary of the characteristics of smart groups in their original study (not directly linked in the Times piece, but accessible on page 686 of Science, October 2010):