1. A computer-implemented method, performed by at least one processor, for using environmental conditions in addition to other dialog state information in a conversational dialog system, comprising: receiving a user dialog act requesting a computer system to perform a task; based on the user dialog act, determining a first machine action to perform the task; accessing environmental conditions that are associated with the user dialog act; based on the environmental conditions and the user dialog act, determining a second machine action other than performing the task, wherein the second machine action at least temporarily prevents completion of the first machine action; and performing the second machine action to provide a response to a user.