The trail making test (TMT) was developed in 1944 as a component of the Army Individual Test Battery, and is commonly used today to test for cognitive impairment. The test involves participants being asked to draw lines on a page, connecting 25 numbered points as quickly as possible. In a second part of the test, participants draw lines alternating between points with numbers and point with letters. Both tasks are to be carried out as quickly as possible.
Source: Kortte, K.B., Horner, M.D., Windham, W.K. (2002). The Trail Making Test, part B: Cognitive flexibility or ability to maintain set? Applied Neuropsychology, 9, 106–109.