Facial discrimination tasks (age, happy-neutral, and sad-neutral) were developed to address the need for activation tasks that engage emotional processing and can be used during physiologic neuroimaging ("neurobehavioral probes"). The stimuli pictured professional actors and actresses who had been screened for asymmetric features. In experiment I, same-sex stimuli were used to examine the performance of normal subjects (24 men, 15 women) on the three tasks. Performance was better during the emotion-discrimination tasks than during the age-discrimination task, and males had higher sensitivity scores for the detection of sad emotion. However, experiment II showed that the sex of the stimulus interacts with the sex of the subject. Compared with female subjects, male subjects (n = 10) were selectively less sensitive to sad emotion in female faces. Female subjects (n = 10) were more sensitive overall to emotional expression in male faces than in female faces. Thus, men and women differed in performance depending on the sex of the facial stimulus.