1. A method for assessing and grading sensorimotor impairment of a human subject which comprises a) generating in a computer a pattern which comprises a trajectory path, b) classifying said pattern in a class from a plurality of difficulty classes of patterns of incremental difficulty, wherein said difficulty classes are defined by parameters, including (a) number of curves in said trajectory path, (b) acuity of curves in said trajectory path, and (c) speed of the target cursor in curved parts of said trajectory path and in straight parts of said trajectory path, c) placing a movement sensor on the head or limb of said subject, which sensor is connected to said computer such that said computer can trace movements of said sensor, and output a tracing cursor on a display, d) drawing said classified generated trajectory path on said display with a target cursor after the subject has been instructed to follow the target cursor by moving the tracing cursor, such that acuity of curves in said trajectory path and speed of the target cursor are related as defined by a ⅔ Power Law, e) determining the correlation and/or deviation of said tracing cursor from said target cursor, wherein the correlation measurement comprises determining an amplitude accuracy, a directional accuracy, and a jerk index, f) determining a graded impairment assessment of sensorimotor function of said subject, based on the measured correlation and/or deviation in step e).