A set of intonation contours has been synthesized using "yes" as the carrier word. Discrimination and identification functions have been obtained for these intonation contours. It was found that the stimuli could be classified as "statement," "question," "emphatic statement," and, possibly, "hesitation" and "weak statement." Predicted discrimination functions were calculated from the identification functions, and these were found to be positively correlated with the obtained discrimination functions. This provides evidence for category boundary effects in the perception of intonation.