1. A system for training a trainee to recognize facial expressions from animations of computer-simulated faces, the system comprising: a trainee interface configured to display a facial animation; a non-transitory machine-readable repository of facial expression overlays each corresponding to an emotion; a non-transitory computer-readable storage medium encoded with a computer program with instructions for combining one of the expression overlays into a facial animation to form a combined animation, by mapping at least a portion of the expression overlay to at least a portion of the facial animation, the computer program further including instructions to provide the combined animation for display in the trainee interface; a non-transitory computer-readable storage medium encoded with a computer program with instructions for executing a trainee evaluation module for evaluating a trainee's performance in correctly recognizing displayed facial expressions in the combined animation, the trainee evaluation module configured to receive from the trainee a response to the combined animation displayed in the trainee interface; and a computer system operative to execute at least one of the trainee interface, the computer program in the computer-readable storage medium, and the trainee evaluation module, the computer system also operative to access the repository.