Two-Point Discrimination

Definition

Measure of fine tactual perception that assesses the minimal distance between two stimuli that can be perceived as separate.

Current Knowledge

When the surface of the skin is touched simultaneously by two relatively fine points (such as a compass or the two ends of a paper clip), the sensation may be perceived as either a single or two separate sites being stimulated. Whether felt as a “single” or “two-point” stimulation will depend on the distance between the points, the area of the body being stimulated, age of the patient, and the integrity of the nervous system. Some parts of the body (such as the tip of the tongue, the lips, and the fingertips) are more sensitive than others (e.g., the hand or arm, which in turn are much more sensitive than the back). Distances of just 2–3 mm can usually be discerned on the tongue and lips and just slightly more on the fingertips (3–5 mm). Separations of approximately 1 cm may be discriminated on the palm of the hand, whereas it may...