Typically, only one sense is affected: Hearing (auditory agnosia—the inability to identify objects through sound such as a ringing telephone) Taste (gustatory agnosia) Smell (olfactory agnosia) Touch (somatosensory agnosia) Sight (visual agnosia) For example, patients with somatosensory agnosia have difficulty identifying a familiar object (eg, key, safety pin) that is placed in their hand on the side of the body opposite the damage.