Forced-choice tasks measure which of a limited number of potential answers participants choose for different stimuli. At its core, it is a discrimination task that shows how well participants can perceive a specific difference between several stimuli. If constructed carefully, the task can measure recognition or even full psychometric functions. In a forced-choice task, participants are required to choose from a limited number of explicitly listed alternatives. The alternatives describe some aspect of the stimuli (such as its color, shape, location, painting style, etc.). The alternatives are almost always mutually exclusive (i.e., if one alternative is true, then the others cannot be) and are often mutually exhaustive (i.e., they cover all possible options). They are specifically tailored to the experiment and thus require prior knowledge about the expected results.