the Psychological record, 2008, 58, 443–464 a coMPaRison oF “diRecT” VeRsUs “deRiVed” exTincTion oF aVoidance ResPonding Bryan. t. roche National University of ireland, Maynooth Jonathan W. Kanter and Keri r. Brown University of Wisconsin–Milwaukee Simon Dymond University of Wales, Swansea ciara c. Fogarty National University of ireland, Maynooth To establish a series of derived relations between arbitrary stimuli, 20 subjects were exposed to nonarbitrary and arbitrary relational training and testing pro- cedures. Subjects were then exposed to an avoidance conditioning procedure in which one member from each relation was established as a discriminative stimulus for avoidance and nonavoidance, respectively. Subjects who showed conditioned avoidance and nonavoidance also showed derived avoidance and nonavoidance to other relation members. All subjects were then exposed to one of two extinction procedures, in which the original discriminative stimuli or other class members were employed, respectively. The majority of subjects ex- posed to both procedures also demonstrated spontaneous derived extinction of avoidance responding. These findings may have several important treatment implications. Several decades of research on stimulus equivalence have demonstrated that verbally able humans can relate stimuli in the absence of direct training after being taught a series of related conditional discriminations. For example, if a subject is taught to relate A to B and A to c, the subject will likely relate B to A, c to A, B to c, and c to B without any additional training. one interesting property of these derived relations is that often a response trained to one member of an equivalence class will transfer to other members of that class without any direct training and even though the class members share no formal properties (e.g., Dougher & Markham, 1994). Several studies correspondence concerning this article should be addressed to Bryan roche, Department of Psychology, National University of ireland, Maynooth, co. K ildare, ireland. e-mail: Bryan.t.roche@nuim.ie