An implicit association test (IAT) measures differential association of 2 target concepts with an attribute. The 2 concepts appear in a 2-choice task (e.g., flower vs. insect names), and the attribute in a 2nd task (e.g., pleasant vs. unpleasant words for an evaluation attribute). When instructions oblige highly associated categories (e.g., flower + pleasant) to share a response key, performance is faster than when less associated categories (e.g., insect + pleasant) share a key. This performance difference implicitly measures differential association of the 2 concepts with the attribute. In 3 experiments, the IAT was sensitive to (a) near-universal evaluative differences (e.g., flower vs. insect), (b) expected individual differences in evaluative associations (Japanese + pleasant vs. Korean + pleasant for Japanese vs. Korean subjects), and (c) consciously disavowed evaluative differences (Black + pleasant vs. White + pleasant for self-described unprejudiced White subjects).Consider a thought experiment. You are shown a series of male and female faces, to which you are to respond as rapidly as possible by saying "hello" if the face is male and "goodbye" if it is female. For a second task, you are shown a series of male and female names, to which you are to respond rapidly with ' 'hello" for male names and "goodbye" for female names. These discriminations are both designed to be easy--the faces and names are unambiguously male or female. For a final task you are asked to perform both of these discriminations alternately. That is, you are shown a series of alternating faces and names, and you are to say "hello" if the face or name is male and "goodbye" if the face or name is female. If you guess that this combined task will be easy, you are correct. Now imagine a small variation of the thought experiment. The first discrimination is the same ("hello" to male faces, "goodbye" to female faces), but the second is reversed ( "goodbye" to male names, "hello" to female names). As with the first experiment, each of these tasks, by itself, is easy. However, when you contemplate mixing the two tasks ("hello" to male face or female name and "goodbye" to female face or male name), you may suspect that this new combined task will be difficult. Unless you wish to make many errors, you will have to respond considerably more slowly than in the previous experiment.The expected difficulty of the experiment with the reversed Anthony G. Greenwald, Debbie E. McGhee, and Jordan L.K. Schwartz, Department of Psychology, University of Washington.This research was partially supported by Grant SBR-9422242 from the National Science Foundation and Grant MH 41328 from the National Institute of Mental Health. For comments on a draft of this article, the authors thank Mahzarin Banaji, Shelly Famham, Laurie Rudman, and Yuichi Shoda.Correspondence concerning this article should be addressed to Anthony G. Greenwald, Department of Psychology, Box 351525, University of Washington, Seattle, Washington 98195-1525. Electronic mail may be sent to agg@u....