Abstract Alexithymia, a characteristic involving a limited affective vocabulary appears to involve three components: difficulty identifying feelings, difficulty describing feelings, and externally oriented thinking. There is evidence that alexithymic characteristics are associated with differences in emotion information-processing. We examined the role of temporal factors in alexithymic emotion-processing deficits, taking into account the confound between alexithymic characteristics and positive and negative affectivity. One hundred forty-six participants completed the 20-item Toronto Alexithymia Scale and the Positive and Negative Affect Schedule. In a signal-detection paradigm, participants judged facial expressions depicting neutral or negative emotions under slow and rapid presentation conditions. The alexithymia component of difficulty in describing feelings was inversely related to the ability to detect expressions of negative emotion in the speeded condition. This relationship was independent of positive and negative affectivity. Alexithymic components positive and negative affectivity were unrelated to response bias. The results emphasize the influence of difficulty describing feelings within the alexithymia construct and its difference from positive and negative affectivity. They suggest that an alexithymic deficit in describing feelings is associated with a deficit in processing negative emotions that is most apparent when processing capacity is challenged. Theoretical and methodological implications are discussed.