Final answer:
The ability to identify shapes, numbers, and symbols written on one's skin is known as graphesthesia, which is a type of sensory perception test. It is often assessed with stereognosis, another sensory test for identifying objects through touch. These are part of neurological evaluations.
Step-by-step explanation:
The ability to recognize outlines, numbers, words, or symbols written on the skin is known as graphesthesia. This term is related to sensory perception tasks used in neurological evaluation. A common assessment of graphesthesia involves writing numbers or letters on the palm of a hand with a dull object such as a pen cap, with the patient having to identify them with their eyes closed. Another closely related test is stereognosis, which involves identifying common objects, like different types of coins, based solely on the somatosensory information received through manipulation. Key factors the patient relies on are the size, weight, and distinct edges (smooth or corrugated) of the coins.
Vision tests in optometry, such as using a Snellen chart, establish visual acuity by presenting letters of decreasing size and measuring the smallest letters a person with normal acuity should be able to read from a distance of 20 feet.