Haemoencephalography (HEG) is a kind of biofeedback that allows the conscious control of blood flow and metabolism in the brain. It follows the principles of biofeedback. With HEG, the oxygen in the blood in the frontal brain is measured with infrared disensors attached to a simple headband. As the oxygen content and thus metabolism in the prefrontal area of the brain increases, a "reward" is provided by visual animation (e.g., film, computer game, pictures, etc.) as long as the condition continues or continues to improve. If the condition fails, the feedback comes in the form of stopping the film.