An investigation of oddity concept learning by rats

Four male rats (Rattus norvegicus, Long-Evans) 114 days old at pretraining were tested using ping pong balls with food-flavoring odors as discriminanda. Two same-odor and one different-odor balls were presented on each trial, and 60 different problems were administered each to an 80% correct criterion or 100 trials. To assess conceptual use of oddity the first trial of each problem was used; Trials 2 and 3 were used to assess learning set performance. One rat had two significant runs of correct first trials, but he did not sustain it. All rats showed rapid improvement on Trials 2 and 3 affirming their excellent learning set formation. The need and means for continued investigation of oddity concept learning by rats are discussed.