Transfer of a novel discriminative function across functional stimulus class members in rats

This experiment explored a rodent model of functional class formation by assessing the transfer of a novel discriminative function across class members. Following simple successive discrimination reversal training and consistently strong probe performance indicative of the formation of two six-member functional classes (X1–X6 and Y1–Y6), subjects were trained on a novel discrimination task to respond in the right-side port in the presence of odor X1 and in the left-side port in the presence of Y1. When rats demonstrated high accuracy on the left–right (LR) task as well as maintenance of the functional classes, LR probe sessions were conducted in which X2 or Y2 were presented on some trials as nonreinforced probes to test for transfer of the novel function (left or right responding). The LR probe sessions were conducted in this fashion for each pair of X and Y stimuli that had never been directly trained in the LR discrimination procedure. Transfer of the novel function was observed in five out of six subjects on the initial probe session, but only two rats showed consistent transfer across subsequent probes. The results offer preliminary evidence for transfer of novel function in rats and support further investigation using a similar approach.