A neurological test to assess motor coordination, accuracy of voluntary actions, and cerebellar function. The patient is asked to alternately touch his nose and the finger of the researcher, who can change position to complicate the task. Performance disorders, such as missing or the appearance of tremors when moving, may indicate cerebellar lesions, proprioceptive disorders, or motor pathway dysfunction. This test is often used as part of a routine neurological exam when problems with balance, coordination, or movement control are suspected.