Longitude lines go up and down.
The answer is "signal detection theory".
Detection theory or signal detection theory is a way to measure the capacity to perceive between data bearing examples (called stimulus in living organisms, signal in machines) and arbitrary examples that divert from the data (called commotion, comprising of foundation stimulus and irregular action of the recognition machine and of the nervous system of the administrator). In the field of gadgets, the division of such examples from a disguising foundation is alluded to as signal recovery.
