Numeric values of psychological measures often have an arbitrary character before research has grounded their meanings, thereby providing what S. J. Messick (1995) called consequential validity (part of which H. Blanton and J. Jaccard now identify as metric meaningfulness). Some measures are predisposed by their design to acquire meanings easily, an example being the sensitivity measure of signal detection theory. Others are less well prepared, illustrated by most self-report measures of self-esteem. Counter to Blanton and Jaccard's characterization, the Implicit Association Test (IAT) has properties that predispose it to acquire consequential validity rapidly. With the IAT as the subject of over 250 publications since 1998, there is now much evidence for its consequential validity. The IAT has attracted more scholarly criticism than have other measures designed for similar purposes. The authors speculate as to why the IAT is an attractive target.