Abstract: A system for examining the color vision response of a human being utilizes substantially identical multicolor LEDs to function as reference and comparison color light sources. In one embodiment, the colors emitted by the LEDs are controlled by respectively associated voltage dividers. The voltage divider which cooperates with an LED to produce a reference color, is provided with a switching arrangement whereby one of a plurality of reference color compositions can be selected. The comparison color light is controlled by a voltage divider which is substantially continuously adjustable.