In most biobehavioral research using rats as subjects, saccharin is vi
ewed as a ''sugar substitute''-sweet, palatable, and conveniently lack
ing in calories. This characterization has merit: Saccharin seems to s
hare some sensory, affective, and motivating properties with sugars. T
his paper focuses on saccharin's lesser known, aversive properties. Ev
idence of saccharin's distinctive taste in rats is reviewed, followed
by discussion of several modulating variables. Procedures that influen
ce rats' responses to saccharin and their measurement are summarized,
and the argument is advanced that saccharin can be used to study the r
elationship of taste and ingestion to learning, stress, and emotional
processes in rats and humans.