1. A communication assist method, comprising: obtaining brain wave data from an electroencephalograph; analyzing the brain wave data; determining a discriminant function based on the analyzed brain wave data; determining a success rate based on the discriminant function; determining that a specific intention decision has been made in the brain when a product of an accumulated discrimination score according to the discriminant function and the success rate exceeds a threshold value; and outputting a determination result of the specific intention decision to an electronic device; wherein the analyzing and determining steps are performed by a communication assist apparatus, the communication assist apparatus comprising: a stimulus-presenting apparatus; and a processing apparatus that processes the brain wave data from the electroencephalograph that measures a brain wave after stimulus presentation by the stimulus-presenting apparatus.