A method for training rats to lick at high rates for a water reinforcer after presentation of one tastant and to inhibit or decrease response rate to avoid a time-out, punisher after presentation of another tastant is described and evaluated. The method produced rapid acquisition of simple discrimination and detection tasks, The absolute mean detection threshold for sodium chloride in three rats was 0.0038% (0.0031%-0.0043%. The operant conditioning technique is simple, efficient, and should prove useful for psychophysical and physiological studies of gustation.