Provided are systems and methods for medical diagnosis. The systems and methods may identify a coherence between paired sensor data respectively measured from a first sensor attached to a head of a subject and a second sensor attached to a body part of the subject. The systems and methods may determine an amount of volition in the subject's body based on the coherence. The systems and methods may determine a diagnosis or a treatment plan for a subject based on the amount of volition. The system and methods may be used to track interaction between individuals in a clinical setting or in a social group.