Astereognosis

Part of speech: noun

Definitions

1. The neurological inability to identify familiar objects by feeling them with the hands, despite intact sensation of touch, pressure and texture
2. A loss of tactile recognition in which a person cannot name or understand an object held in the hand, though basic touch remains normal
3. A condition caused by damage to the parietal lobe that leaves someone unable to know what an object is merely through handling it

Etymology: Astereognosis is the inability to recognise an object by touch alone, a loss that neurologists identify when a person can feel an object's shape and texture yet cannot name it. The name is built from three Greek pieces: the privative prefix "a-", meaning "not" or "without", the stem "stereo-" from "stereos", meaning "solid" or "three-dimensional", and "gnosis", meaning "knowledge" or "recognition", from "gnōsis". Put together, the term describes knowing a solid thing without sight. The sense of "stereo-" here is a modern scientific coinage. "Stereognosis" was formed in English from the Greek roots, and "astereognosis" was then built by adding "a-" to it. The Greek words themselves did not describe nerve function; the medical term was assembled by English-speaking clinicians from classical building blocks, so the ancient Greeks would not have recognised it as a diagnosis.

Synonyms: tactile agnosia