Psychometrics permits the quantification of cognition, affect and behaviour, thus permitting both the identification of pathology and degree of deviation from normality. These methods have been principally used in older populations to screen affective and cognitive disorders, as an adjunct to the differential diagnosis of different forms of cognitive dysfunction and also to describe and monitor the functional consequences of pathology. The application of psychometric tests in older populations raises several problems, notably the confounding effects of associated pathologies, changing definitions of disease threshold in parallel with advances in medical technology, and inadequate knowledge of normal information processing at higher ages. Computerized assessment, once considered inappropriate in older populations, is now commonly used to standardize administration procedures and tailor testing to individual competency. It has also permitted the more accurate measurement of information processing time, which is important in the diagnosis of many neuropsychiatric disorders.