[1] With the absence of vision (i.e. eyes closed), an individual with astereognosis is unable to identify what is placed in their hand based on cues such as texture, size, spatial properties, and temperature.
In the affected hand(s) they may be able to identify basic shapes such as pyramids and spheres (with abnormally high difficulty) but still not tactilely recognize common objects by easily recognizable and unique features such as a fork by its prongs (though the individual may report feeling a long, metal rod with multiple, pointy rods stemming off in uniform direction).
Josef Gerstmann recounts his experience with patient JH, a 34-year-old infantryman who suffered a lesion to the posterior parietal lobe due to a gunshot.
Following the injury, JH was unable to recognize or identify everyday objects by their meaning, origin, purpose and use with his left hand using tactile sensation alone.
For more complex objects, his behavior and recognition varied daily based on his tactile resources that changed over time and depended on his fatigue.