To test human itch response, apply an itching (aka pruritic) agent. You could use histamine (intradermal), cowhage (punctate) or capsaicin (topical) in metered quantities. Then use a coping saw with a medial gauze pad. Stroke with a downward “compressional force” of 100mN, and with each stroke move to and fro 40 millimeters per second. To find allokinesis, test along surrounding radial pathways until the site is fully mapped.
Credit for the technique goes to Parul Sikand, Steven Shimada, Barry Green and Robert LaMotte. I learned about this from reading a paper written by anesthesiologists working in and around New Haven. It’s a nice trick, as it requires only a coping saw and a gauze pad. If only electrically-induced itch were so easy.
Citation: “Similar itch and nociception sensations evoked by punctate cutaneous application of capsaicin, histamine and cowhage.” PAIN 144 (2009) 66-75