This study investigated whether social anxiety facilitates the discrimination between genuine and ambiguous smiles. Socially anxious (N=20) and nonanxious (N=20) participants categorized as “happy” or “not happy” faces with either (1) a truly happy expression (i.e., happy eyes and a smile), (2) truly nonhappy expressions (e.g., angry eyes and an angry mouth), or (3) blended expressions with a smiling mouth and nonhappy (e.g., angry, sad, etc.) eyes. Results indicated that, relative to nonanxious participants, those high in social anxiety weremore likelyto judge as “not happy” any blended expression with nonhappy eyes, and they werefasterin judging as “not happy” the blended expressions with angry, fearful, or disgusted eyes (but not those with sad, surprised, or neutral eyes). These results suggest, respectively, that social anxiety inhibits a benign interpretation ofallthe ambiguous expressions with a smile, and speeds up the detection ofthreateningeyes in such expressions. Importantly, no differences appeared as a function of social anxiety for truly happy or nonhappy faces. This rules out a response-bias explanation, and also reveals that social anxiety does not affect sensitivity in the recognition of prototypical expressions. [ABSTRACT FROM PUBLISHER]