The DTLA-5 is now available! Learn more. The Detroit Tests of Learning Aptitude (DTLA-4) is one of the oldest and most respected tests that evaluate specific mental abilities of individuals ages 6 to 17. The test includes interpretation in terms of current theories of intelligence. The DTLA-4 is the test of choice for professionals interested in a thorough investigation of an individual's specific cognitive functions. The DTLA-4 measures basic abilities, and shows the effects of language attention, and motor abilities on test performance.