12. The non-transitory computer-readable medium of claim 9 , further comprising receiving contextual information used for detecting the emotion of the user, the contextual information comprising at least one of differential statistics, joint statistics, distance statistics, and statistics collected during a prior dialog between the user and the computing device including (1) differential information of prosodic features, (2) temporal variation of emotion indicators inter-utterance, and (3) temporal variation of emotion indicators intra-utterance.
9. A non-transitory computer-readable medium, storing instructions for controlling a computing device to detect emotion during a natural language dialog between a user and the computing device, the instructions comprising: receiving an utterance from the user in a human-computing device natural language dialog; receiving non-repetitive prompts in the natural-language dialog, wherein the non-repetitive prompts are prompts by the computing device; and detecting an emotion of the user based on the utterance and at least in part on the non-repetitive prompts.