Two point discrimination
Two-point discrimination measures the individual’s ability to perceive two points of stimuli presented simultaneously. The health care practitioner is interested in the smallest distance between the points that can still be perceived as two points by the individual being tested.
Expected findings - The measured distance will vary depending on the body part being tested and should be compared to normative data.
Equipment Two-point discrimination aesthesiometer.
Testing procedure
- Explain the procedure to the patient with his/her eyes open. For example, “I am going to touch various parts of your arms (or other body part) with this instrument. I will touch you with either one or two points, and tell me if you feel one or two points when you feel the touch.”
- Demonstrate the procedure with the patient’s eyes open until the patient understands the procedure.
- The patient closes his/her eyes, or vision is otherwise occluded.
- Begin the test with the points of the anesthesiometer opened greater than the mean value for the body part being tested.
- Provide the stimulus by applying light and equal pressure across the two points.
- Have the patient identify if they feel one or two points.
- Move the two points closer together across consecutive trials until the patient cannot distinguish the two points as separate.
- Measure the distance between the two points using the aesthesiometer ruler.
- Repeat throughout suspected areas and document findings.
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