Neuropsychological testing provides an important adjunct to diagnosis and prognosis in geriatric assessment, which has become of increasing importance in light of the rising prevalence of neuropsychiatric disorders for which no specific biological marker is presently available. Neuropsychological testing itself involves the observation of an individual's behavior in relation to a given stimulus selected for its likelihood to provoke an abnormal response in the face of damage to a specific neuroanatomical structure. The theoretical basis of neuropsychological assessment is derived both from cognitive psychology, which deals with the development of cognitive tests for the demonstration of theoretical models of cognitive functioning, and also from behavioral neurology, which aims at the classification of normal and pathological responses to cognitive stimuli with a view to screening central nervous system disorder.