A computer-controlled, multiple-channel odor generator, operant test chamber, and discrimination training procedure for mice are described. The odor generator allows controlled presentation of any one or combinations of eight odors to an odor-sampling port that contains a liquid reinforcement delivery tube that also serves to detect responses. A modified discrete trial operant conditioning procedure provides measures of both response accuracy and response rate during anticipation of stimulus delivery and in the presence of two different odor stimuli. Results from numerous experiments demonstrate that, with these methods, mice reliably and rapidly acquire odor detection and a variety of odor-discrimination tasks, and that response rate in the presence of the odor reflects the incentive motivation of stimuli that are or are not associated with reward.