Astereognosis

An inability to recognize objects by touch when they are placed in the hand, even though there is no defect of sensation in the fingers or difficulty in holding the object. Astereognosis is either left- or right-sided; tactile recognition is normal on the other side. If both sides are affected, the condition is called tactile agnosia. Astereognosis and tactile agnosia are caused by damage to parts of the cerebrum (main brain mass) involved in recognition by touch and may occur as a result of a stroke or head injury.