Disclosed are a system and method for detecting a gesture performed by a user of a device. The device includes a screen having a backlight as with a liquid-crystal type display or which provides its own illumination as with a light-emitting diode type display. The device is programmed to emit a detectable optical signal from one or more distinct zones of the display. The device further includes an optical receiver for detecting any reflections of the emitted detectable optical signal. When a user's hand is located in proximity to the device display, the reflections of the detectable optical signal from that appendage are detected by the optical receiver and are used by the device to determine the presence and direction of travel of the user hand, signifying a user gesture. The distinct zones of the backlight may consist of a single zone, and the optical receiver may comprise multiple receivers.