Although this area of psychology developed quite slowly historically, it is currently one of the most prominent areas. It was not until World War I (1914-1918) that many psychologists began to work in applied settings for the first time, and began to perform "mental" testing. Approximately two thirds of psychologists today spent at least some of their time working in the applied fields, including clinical psychology, neuropsychology, counselling psychology, school psychology, industrial and organizational psychology, law, business, consumer affairs, engineering, and the military.