Figure 3: H5 Probe and Control Data Bar 1: Percent correct on regular probe trials. Bar 2: Percent correct on probes with blind exp. Bar 3: Percent correct for probes without pellets in the cups. TWO-CHOICE OPERANT CHAMBER & ODOR ARENA TRIALS: Two stimuli, one from each set were randomly placed into the arena or the two cup holders in Operant chamber with the rest of the holes in Arena being occupied by empty 2 oz cups. RESPONSES: any displacement of the lid with the paws or nose that exposes the sand in Arena or displacement of sand by paws or nose in a digging motion in Two-choice Operant Chamber. Responses to the S+ stimulus set result in food pellet reinforcement and terminate the trial. CRITERION: When accuracy reached 90% or higher for two consecutive sessions, the contingency was reversed such that the S+ becomes negative and the S- set, positive. STIMULI: Household spices were mixed with play sand at a ratio of 1g of spice/100g of sand (based on preliminary data indicating that the scent of the food pellet was masked at these concentrations). Functional Equivalence in Rats with Olfactory Stimuli Rayburn-Reeves, R. M., Bullard, L., Poerstel, L. B., Bruce, K. & Galizio, M. University of North Carolina Wilmington Contact info: INTRODUCTION Equivalence is usually studied using a conditional discrimination procedure. However, successful demonstration in non-humans has been limited. A related procedure has been more successful in demonstrating a type of equivalence in non-human animals. Vaughan (1988) demonstrated functional equivalence in pigeons using a simple discrimination, repeated reversals procedure. Stimuli were grouped into two sets; one being designated as positive and one as negative at the onset of the experiment. Subjects were trained to reliably respond to the positive set and once criterion levels of performance were reached, contingencies were reversed (the positive set became negative and vise versa). After a series of reversals, once a few stimuli from the set had been reversed, the subjects correctly responded to the rest of the stimuli from that set without explicit reinforcement; functional equivalence. The current experiment replicated the Vaughan procedure in rats using olfactory stimuli. Delius et al. (2000) used a variation of the functional equivalence procedure involving only two pairs of stimuli in which pigeons were trained to criterion on one stimulus of the pair and tested on the other stimulus within that set. Conclusions Above chance probe performance provided evidence for functional equivalence for two rats (H5 and F8) in the Two Choice Operant Chamber Reduction in the number of sessions to reach criterion was seen as a function of the number of reversals in all rats Delius versus Vaughan procedure: Rats H5 & F8 in Two Choice show above chance probe performance in Delius but not Vaughan Rats F7 and F4 in Arena do not show above chance performance in either procedure (although F7 is showing a trend for improved probe performance). F7 SPICE LIST SET 1 SET 2 Cinnamon Turmeric Onion Rosemary Sage Paprika Bay Fen Garlic Nut Caraway Cumin Ginger Mustard Celery Oregano Sumac Marjoram Thyme Clove 37in diameter; 11 ½ in high; 120in perimeter; holes 5cm & 5 ½ in apart; 1-12 (o); (I) Reversal # PERCENTCORRECTPERCENTCORRECT PROBE DATA RESULTS Procedure Each session consisted of 20 trials. Each stimulus is presented twice per session and all stimuli presented in the first ten trials are then repeated in a random order for the last ten trials. Probe trials were considered the first ten trials on the first day of a reversal. Because acquisition was slow with the Vaughn procedure, a new procedure based on Delius et al. was implemented. To begin each reversal, two pairs of stimuli were trained to criterion, and the remaining eight were then tested for functional equivalence. In a final phase, we set a more stringent criterion requirement of 90% or higher for one full session, followed by 10/12 correct the following session with the first two pairs before testing the eight probes. REFERENCES Sidman, M. & Tailby, W. (1982). Conditional discrimination vs. matching-to- sample: An expansion of the testing paradigm. Journal of the Experimental Analysis of Behavior, 37, Vaughan, W. Jr. (1988). Formation of equivalence sets in pigeons. Journal of Experimental Psychology: Animal Behavior Processes, 14, Delius, J. D., Jitsumori, M., Siemann, M. (2000). Stimulus Equivalences through discrimination reversals. In C. Heyes & R. Huber (Eds.), The evolution of cognition (pp ). Cambridge, MA: MIT Press. TWO-CHOICE OPERANT CHAMBER ODOR ARENA REVERSAL # SESSIONS SESSIONS TO CRITERION F4 F7 Figure 1: Sessions to reach criterion as a function of the number of reversals Figure 2: Percent correct on probe days as a function of the number of reversals Arena H5 F8 Two Choice