The Function Acquisition Speed Test (FAST): A behavior-analytic implicit test for assessing stimulus relations.

Subjects completed a baseline stimulus matching procedure designed to pro-duce two symmetrical stimulus relations; A1–B1 and A2–B2. Using A1, B1, and two novel stimuli, subjects were then trained to produce a common key-press response for two stimuli and a second key-press response for two fur-ther stimuli across two blocks of response training. During one block, the re-inforcement contingencies were consistent with baseline relations (i.e., A1 and B1 shared a response function), whereas during the other block they were not. Thirteen of 18 subjects who completed the procedure showed a response class acquisition rate differential across the two test blocks in the predicted direc-tion. It is suggested that this procedure may serve as a behavior analytic alter-native to popular implicit tests. It provides a nonrelative measure of stimulus association strength and may display superior procedural implicitness over other tests. There has been considerable recent interest in developing behavior analytic "implicit" tests for assessing histories of relational responding and stimulus relations generally. This interest can be traced to the finding that the stimulus relations formed during a subject's social history may interfere with the formation of novel stimulus relations, such as equivalence classes. Specifically, in what can now be surely described as a seminal study, Watt, Keenan, Barnes, and Cairns (1991) used a simple stimulus