Stereognose

Stereognosis, or tactile object recognition, is the ability to identify objects by touch in the absence of visual cues. It relies on exploratory hand movements to gather information about an object's shape, texture, size, weight, and other properties, which are then integrated by higher-order sensory and cognitive systems to form a recognizable percept.

Neural basis and processing involve the somatosensory pathways, with initial reception in the somatosensory cortices and subsequent processing in associative areas, including the secondary somatosensory cortex and the posterior parietal cortex. These regions integrate tactile and proprioceptive input with memory and expectation to produce a coherent perception of the object. Effective stereognosis depends on intact somatosensation and higher-level integrative processing.

Clinical assessment of stereognosis is part of a neurological exam. With vision occluded, a clinician presents common objects (e.g., key, coin, small tool) and asks the patient to identify them by touch alone. Performance helps distinguish intact basic sensation from higher-order tactile recognition. Impairment, known as astereognosis (tactile agnosia), occurs despite preserved basic somatosensory thresholds and can indicate a lesion in the contralateral parietal lobe or associated somatosensory pathways, often after stroke, trauma, or neurodegenerative disease.

Stereognosis is one component of tactile gnosis, alongside other forms of object recognition via touch. Its assessment aids in localizing sensory and cortical dysfunction and informs rehabilitation planning.