Systems and techniques are disclosed for aspects of processing physiological signals in connection with the selection and output of sensory stimuli. In an example, a system for modulating the cognitive state or physiological activity of a human subject may be used in a variety of settings, such as for offering exposure therapy or other forms of guided psychological treatment, based on the presentation and control of a sensory stimulus to a human subject. In another example, a system for generating or training a physiological response model may be established to classify or identify a cognitive response state from sensory stimulus, such as media content, based on the identification of a physiologic or cognitive response state produced from physiological response signals during exposure to the sensory stimulus.