Sick people may have difficulty thinking clearly, which is worrisome because they often need to make complicated medical decisions. Surprisingly, the ability of sick people to think has not been carefully studied. Doctors sometimes use a test called the Mini-Mental Status Examination (MMSE) to judge patients' thinking. The MMSE involves simple tests of orientation (for example, name the year), memory (for example, remember three objects), attention (for example, spell “world” backwards), and language (for example, name familiar objects or read and write a sentence). Jean Piaget, a psychologist, developed a set of tasks that test the thinking of young children. An example of Piaget's tasks is the “conservation of volume” task. In this task, the tester shows the person being tested two identical, short wide glasses containing equal amounts of water. The tester then pours water from one of these glasses into a tall, narrow glass, and asks the person whether the short, wide glass that still has water in it and the tall narrow glass contain the same amount of water. Young children often say that the tall narrow glass contains more water even though it does not. It is unknown whether sick people with normal MMSE scores might display the types of thinking problems that Piaget's tasks evaluate.