Within computer technology, the gaze-contingency paradigm is a general term for techniques allowing a computer screen display to change in function depending on where the viewer is looking. Gaze-contingent techniques are part of the eye movement field of study in psychology.
From a system analysis point of view, eye-tracking applications should be distinguished from diagnostic or interactive system. In diagnostic mode, the eye tracker provides data about the observer's visual search and attention processes. In interactive mode, the eye-tracker is used as an input device. From a general point of view, an interactive system responds to the observer's actions and interacts with them. Because the display updates in response to the observer's eye movements, the gaze-contingency paradigm can be classified an interactive eye-tracking application.[1]