A method is presented to address quantitative assessment of functional impairment in a subject, where the method comprises the steps of: (1) presenting a plurality of tests to a subject on a display, the plurality of tests comprising a series of scenes, the scene comprising at least one stimulus, wherein the scene may be associated with visual, auditory, and tactile stimulus arrays; (2) modulating at least one spatial characteristic of at least one stimulus; (3) receiving feedback from the subject via at least one input device; (4) quantitatively refining the scene relative to the received feedback; (5) calculating the relationship between at least one of the scene, the stimulus, and the quantitatively refined scene; (6) adjusting the scene relative to the calculated relationship; (7) determining equilibrated scene parameter of the subject; (8) recording the equilibrated scene parameter onto a tangible computer readable medium; (9) generating at least one diagnosis to the functional impairment associated with the equilibrated scene parameter; (10) recommending at least one treatment to the subject. An apparatus for quantitative assessment of functional impairment in a subject comprising an input device, a display device, a control device, and a tangible computer readable medium. A quantitative assessment profile of functional impairment by continuous modulation of specific perceptual domains on a stimulus and generating psychophysical responses on a tangible computer readable medium.