Since 1948, the test has been used by neuropsychologists and clinical psychologists in patients with acquired brain injury, neurodegenerative disease, or mental illness such as schizophrenia. It is one of several psychological tests which can be administered to patients to measure frontal lobe dysfunction. When administered, the WCST allows the clinician speculate to the following "frontal" lobe functions: strategic planning, organized searching, utilizing environmental feedback to shift cognitive sets, directing behavior toward achieving a goal, and modulating impulsive responding. The test can be administered to those from 6.5 years to 89 years of age. The WCST, relies upon a number of cognitive functions including attention, working memory, and visual processing.