The Morris water navigation task, also known as the Morris water maze (not to be confused with water maze), is a behavioral procedure mostly used with rodents. It is widely used in behavioral neuroscience to study spatial learning and memory. It enables learning, memory, and spatial working to be studied with great accuracy, and can also be used to assess damage to particular cortical regions of the brain. It is used by neuroscientists to measure the effect of neurocognitive disorders on spatial learning and possible neural treatments, to test the effect of lesions to the brain in areas concerned with memory, and to study how age influences cognitive function and spatial learning. The task is also used as a tool to study drug-abuse, neural systems, neurotransmitters, and brain development. Overview The basic procedure for the Morris water navigation task is that the rat is placed in a large circular pool and is required to find an invisible or visible platform that allows it to escape the water by using various cues. Many factors can influence the rats' performance, including their sex, the environment in which they were raised, exposure to drugs, etc. There are three basic tactics for the rats to escape the maze: a praxic strategy (remembering the movements needed to get to the platform), a taxic strategy (the rat uses visual cues to reach their destinations), or spatial strategy (using distal cues as points of reference to locate themselves). There are a variety of paradigms for the water maze that can be used to examine different cognitive functions. In particular, cognitive flexibility can be assessed using a water maze paradigm in which the hidden platform is continually re-located. History The Morris water navigation task was conceived by Richard G. Morris (then at the University of St Andrews) in 1981 as an alternative to the radial maze. The test was developed to study spatial learning and how it differed from other forms of associative learning. Originally rats, now more commonly mice, were placed in an open pool and the latency to escape was measured for up to six trials a day for 2–14 days. Several variables are used to evaluate an animal's performance. For example, a "probe trial" measures how long the test subject spends in the "target quadrant" (the quadrant with the hidden platform). More elaborate trials alter the location of the hidden platform, or measure distance spent