Professor of psychology Matthew Nock studies suicide: what causes people to take their own lives; how to predict who will try; and how to prevent it from happening. Nock adapted the Stroop test and the Implicit Association Test—two computerized tests used for other purposes in psychology—to assess suicide risk. Watch the video below to see how these tests work. Read more about Nock's work—and find other relevant links, such as a tool for assessing self-injurious behavior such as cutting—in "A Tragedy and a Mystery," from the January-February 2011 issue (and the sidebar, "Studying Self-Injury"). See also "The Enigma of Suicide," a 1983 Harvard Magazine feature by George Howe Colt.