An amusement system is provided wherein a variation of light intensity transmitted through a living body which reflects a metabolite concentration or concentration variation in the living body reflecting a mental state or brain activity, is measured, and the measurement result is reflected in an object displayed on a screen. By bringing a light illumination device and light detector in contact with the skin of a subject, the intensity of the light propagated in the subject is detected, and the detection result is transmitted to an electronic calculator. The position, shape or color of the object displayed on the screen is made to vary according to the variation of this detected intensity. Thus, human thought can be measured and the state of the object on the screen controlled without using an existing input device such as a mouse, joystick or handle.
Amusement system based on an optical instrumentation method for the living body