In the IAT a subject responds to a series of items that are to be classified into four categories – typically, two representing a concept discrimination such as flowers versus insects and two representing an attribute discrimination such as pleasant versus unpleasant valence. Subjects are asked to respond rapidly with a right-hand key press to items representing one concept and one attribute (e.g., insects and pleasant), and with a left-hand key press to items from the remaining two categories (e.g., flowers and unpleasant). Subjects then perform a second task in which the key assignments for one of the pairs is switched (such that flowers and pleasant share a response, likewise insects and unpleasant). The IAT produces measures derived from latencies of responses to these two tasks. These measures are interpreted in terms of association strengths by assuming that subjects respond more rapidly when the concept and attribute mapped onto the same response are strongly associated (e.g., flowers and pleasant) than when they are weakly associated (e.g., insects and pleasant).