Final answer:
Measure Agnosia on the left side using the RACE scale involves evaluating the patient's ability for tactile recognition of objects and characters with eyes closed, which may indicate cortical damage if perception is lacking. Stereognosis and graphesthesia are key subtests for this assessment.
Step-by-step explanation:
To measure Agnosia on the left side using the RACE scale, one must evaluate the patient's ability to recognize objects or sensory stimuli despite having normal sensory function, which is indicative of a higher-order perceptual issue. The test for sensory perception includes subtests like stereognosis and graphesthesia, where the patient must identify objects or letters and numbers by touch without the aid of vision. If there is a lack of perception on one side during double simultaneous stimulation, this might indicate damage to the contralateral posterior parietal lobe.
For instance, the patient would keep their eyes closed while being handed a common object, such as a coin, and would be asked to differentiate it on the basis of sensory cues (size, texture). In graphesthesia, numbers or letters are written on the palm, and the patient is expected to identify them. Difficulty in performing these tasks suggests the presence of agnosia, likely due to cortical damage in areas responsible for conscious perception. Praxis and gnosis are key areas evaluated in these subtests, linking to the function of language and the cortical processing of sensory information.